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UBC Theses and Dissertations

The antithyrogenic effect of thiamine, riboflavin, and pyridoxine on the basal metabolic rate, after… Goranson, Ewald Swan 1943

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The A n t i t h y r o g e n i e E f f e c t o f Thiamine, R i b o f l a v i n , a n d P y r i d o x i n e on the B a s a l M e t a b o l i c R a t e , a f t e r Induced Hyper-t h y r o i d i s m hy ' Ewald Swan Goranson, B.A. A T h e s i s s u b m i t t e d i n P a r t i a l F u l f i l m e n t o f The Requirements f o r the Degree of MASTER OF ARTS i n the Department of , ZOOLOGY The U n i v e r s i t y o f B r i t i s h Columbia October, 1943. ACKNOWLEDGMENTS I w o u l d , l i k e t o express my s i n c e r e t h a n k s , Dr. J . A l l a r d y c e , under whose d i r e c t i o n t h i s r e s e a r c h was c a r r i e d out. Dr. W. A. Clemens, f o r t h e i n t e r e s t t a k e n i n t h i s work. •Professor G» J . Spencer, f o r . t h e ' e x a m i n a t i o n of s l i d e s o f g l a n d u l a r t i s s u e , which i t had been i n t e n d e d t o use i n t h i s work, anffl t o Mr. K. S t a r k , f o r t h e p r e p a r a t i o n o f the s l i d e s . Dr. W. J . L a i n g , Shaughnessy M i l i t a r y H o s p i t a l , . f o r i n f o r m a t i o n r e g a r d i n g t h y r o i d t h e r a p y and f o r a d e m o n s t r a t i o n of t h e apparatus used i n making B.M..R. d e t e r m i n a t i o n s . i i i TABLE OF CONTENTS ' Page 1. INTRODUCTION 1. 11. .  SURVEY 6. A. I n d i c a t i o n s f o r the Use o f V i t a m i n B l , B2, and B6 Supplements i n H y p e r t h y r o i d i s m 6. a. Weight Loss and A n o r e x i a 6. b. G l y c o l y s i s . 8» c. T i s s u e Loss of V i t a m i n B l 9, d. Metabolism 9. B. T o l e r a n c e t o t h e V i t a m i n s B1 ?B2, and B6 10. C. F a c t o r s Governing the B a s a l M e t a b o l i c Rate 11. a. F a s t i n g „ 11. b. E n v i r o n m e n t a l Temperature- 12. c. Time o f Day 22. d. Age , 13. e. B a r o m e t r i c P r e s s u r e . 13. D. T h y r o i d P r e p a r a t i o n s and Manner o f A d m i n i s t r a t i o n " 13. I I I . EXPERIMENTAL 16. A. Animals 16. B. Environment 16. C» D i e t 17. D. Source o f T h y r o x i n and V i t a m i n s ' 17. i v . Page E. The Apparatus 19. a. M o d i f i c a t i o n s from t h e O r i g i n a l Design 19. , . b. O p e r a t i o n 23. P. Measurement o f the B.M.R. 25. G. Methods Employed 28. a. F a c t o r s I n f l u e n c i n g t h e B.M.R. 28. • ', . 1. F a s t i n g 28. 2. E n v i r o n m e n t a l Temperature 29.. 3. Age ' 29. 4. Time o f Day 30. b. D e s i c c a t e d T h y r o i d 30. 1. A d m i n i s t e r e d a f t e r F a s t i n g 30. 2. A d m i n i s t e r e d p r i o r t o F a s t i n g 31. c. V i t a m i n s B1,B2,B6,and l / l O G r a i n T h y r o i d 32. d. V i t a m i n s B1,B2,B6, and -J- G r a i n T h y r o i d 33. v e. C o n t r o l s 34. RESULTS ( Tabl e s and Graphs ) _35-49 i n c l . DISCUSSION ^50. A. Animals 50. B. Apparatus 50. C. F a c t o r s A f f e c t i n g the B.M.R. 51. a. F a s t i n g 51. b. Temperature 52. Page c. Age 54. d. Time o f Day 55. D. D e s i c c a t e d T h y r o i d 55. a. A d m i n i s t e r e d a f t e r P a s t i n g 55. b. A d m i n i s t e r e d p r i o r t o P a s t i n g 56. E. V i t a m i n s and the T h y r o i d . 5 7 . a.- V i t a m i n s B1,B2,B6 and l / l O G r a i n T h y r o i d 57. b. V i t a m i n s B1,B2,.B6 and £ G r a i n T h y r o i d F. C o n t r o l s V I . SUMMARY V I I . REFERENCES CITED 58. 60. 61. 65. THE ANTITHYROGENIC EFFECT OF THIAMINE,RIBOFLAVIN, AND PYRIDOXINE ON THE BASAL METABOLIC RATE,AFTER INDUCED HYPERTHYROIDISM INTRODUCTION ; ~". . The i n v e s t i g a t i o n of v a r i o u s substances bene-f i c i a l i n t h y r o i d t h e r a p y has c l a i m e d t h e a t t e n t i o n of a l a r g e number of workers d u r i n g t h e p a s t t h i r t y y e a r s . A very good summary of t h i s work, p r i o r t o 1935, has been g i v e n by A.T.Cameron(6). Among the substances s t a t e d t o have produced s a t i s f a c t o r y r e s u l t s are q u i n i n e , i n s u l i n , a d r e n o c o r t i c a l hormone,potassium permanganate, sodium or a mmonlum f l u o r i d e , and c e r t a i n s a l t s of c o p p e r , a r s e n i c and o t h e r minerals..Though e n t h u s i a s t i c c l a i m s were made s p o r a d i c a l l y f o r t h e i r t h e r a p e u t i c use i n a l l e v i a t i n g the h y p e r t h y r o i d c o n d i t i o n , most of t h e s e c l a i m s have a p p a r e n t l y been d i s p u t e d . Other attempts t o t r e a t h y p e r t h y r o i d c o n d i t i o n s by t h e r a p e u t i c measures i n c l u d e d t h e use of serum of t h y r o i d e c t o m i z e d a n i m a l s , o f myxedematous p a t i e n t s , o r t h e "immune serum" from goats f e d t h y r o i d p r e p a r a t i o n s . The u n d e r l y i n g p r i n c i p l e of such t h e r a p y was based on the f a c t t h a t the b l o o d or t i s s u e s c o n t a i n e d a substance a n t a g o n i s t i c " t o the t h y r o i d p r i n c i p l e , a l t h o u g h d i v e r s e and c o n t r a d i c t o r y views were h e l d as t o t h e n a t u r e o f t h i s a n t a g o n i s t i c p r i n c i p l e . Romeis(6) suggested t h a t a s p e c i f i c p r o t e c t i v e compound does e x i s t . He found t h a t i f he added b l o o d a l o n g w i t h t h y r o x i n e t o water c o n t a i n i n g t a d p o l e s , the well-known metamorphosis and r e t a r d a t i o n of growth produced by t h y r o x i n e •-"'did not appear. A d r i e d - b l o o d p r e p a r a t i o n has been employed w i t h b e n e f i c i a l r e s u l t s , a l t h o u g h c e r t a i n d i e t a r y r e s t r i c t -i o n s must be e n f o r c e d . I f the treatment i s s p e c i f i c , i t i s d i f f i c u l t t o und e r s t a n d why d i e t a r y s t r i n g e n c y i s n e c e s s a r y . The e x i s t e n c e o f a c h a l o n i c m e c h a n i s m ( i n h i b i t o r y hormone) a c t i n g t o r e s t o r e a h y p e r t h y r o i d c o n d i t i o n t o normal was i n v e s t i g a t e d by S t a r r and PomerenzeC^/) i n 1941. They observed t h a t an o c c a s i o n a l case of h y p e r t h y r o i d i s m s u b s i d e d r a p i d l y as though such a mechanism were i n operation. But attempts t o produce a chalone of t h i s t y p e by t h e admin-i s t r a t i o n of. d e s i c c a t e d t h y r o i d , t h y r o t r o p h i c hormone, v i t a m i n A , v i t a m i n C, or t e s t o s t e r o n e p r o p r i o n a t e proved i n e f f e c t i v e . I n m e d i c a l p r a c t i c e t o d a y , two measures are g e n e r a l l y adopted i n the treatment o f a h y p e r t h y r o i d c o n d i t i o n . Severe cases a r e t r e a t e d by p a r t i a l a b l a t i o n of t h e g l a n d , and l e s s severe o r m i l d e r cases by t h e use of compounds of i o d i n e , u s u a l l y L u g o l ' s s o l u t i o n , w h i c h c o n t a i n s p o t a s s i u m i o d i d e . S i n c e t h y r o i d e c t o m y , performed w h i l e t h e b a s a l m e t a b o l i c r a t e i s h i g h , o f t e n proved f a t a l , p a t i e n t s s u f f e r i n g - f r o m Grave's d i s e a s e a r e u s u a l l y g i v e n i o d i n e i n some form t o reduce the m e t a b o l i c r a t e b e f o r e an o p e r a t i o n . I n some c a s e s , however, p r o l o n g e d pre-o p e r a t i v e t r e a t m e n t w i t h Lugol's s o l u t i o n has been found t o produce a r e f r a c t o r i n e s s t o i o d i n e ( & ) . A f t e r a p e r i o d of twenty days the b e n e f i c i a l e f f e c t s wear o f f , t h e b a s a l m e t a b o l i c r a t e i n c r e a s e s , and the symptoms of the hyper-t h y r o i d c o n d i t i o n r e t u r n . I n m i l d cases of the o v e r -a c t i v e t h y r o i d c o n d i t i o n , a j u d i c i o u s use of i o d i n e i s b e n e f i c i a l , but t h e r e i s a r e c u r r e n c e of' t h e c o n d i t i o n as soon as t h e t r eatment s t o p s . The p r e c i s e a c t i o n of i o d i n e i n remedying the h y p e r t h y r o i d c o n d i t i o n , p a r t i c u l a r l y Grave's d i s e a s e , i s not y e t u n d e r s t o o d . D u r i n g the; l a s t decade an i n c r e a s i n g amount of work has been done on t h e a n t i t h y r o g e n i c a c t i o n o f the B v i t a m i n s . The r e v i e w o f the l i t e r a t u r e , which f o l l o w s , g i v e s a f a i r l y comprehensive survey of t h i s work w h i c h i s concerned m a i n l y w i t h ' t h e e f f e c t of t h e B v i t a m i n s I n c o u n t e r i n g weight l o s s , d i m i n i s h e d f o o d i n t a k e and a n o r e x i a , g l y c o l y s i s of t h e l i v e r and body t i s s u e s , and t h e t i s s u e storage of the v i t a m i n s . The work, i n the main, suggests the use o f t h e B v i t a m i n s i n h y p e r t h y r o i d t h e r a p y , a l t h o u g h some cotmter c l a i m s are a l s o made. The argument advanced h e r e i n f o r the use o f the B v i t a m i n s i n c o m b a t t i n g h y p e r t h y r o i d i s m i s t h a t f a v o r a b l e response t o t r e a t m e n t w i t h v i t a m i n supplements can be expected o n l y when the d i s o r d e r has been caused by d e f i c i e n c y of a s p e c i f i c v i t a m i n o r v i t a m i n s or by i n a b i l i t y t o use them. Since e x c e s s i v e amounts of t h y r o x i n s t i m u l a t e c a t a b o l i s m of the body t i s s u e s and p a r t i c u l a r l y o f t h e l i v e r ( m a i n s t o r a g e 4. depot of t h e B v i t a m i n s which the body i s a b l e t o r e t a i n ) (8 ) , i t i s expected and has indee d been shown t h a t the B v i t a m i n s w i l l , a t t h e same t i m e , be d e p l e t e d o r d e s t r o y e d . Consequently, t h e more t h y r o x i n e made a v a i l a b l e i n t h e body, t h e g r e a t e r the requirement f o r t h e B v i t a m i n s . The d i a g n o s t i c t e s t now g e n e r a l l y employed t o c o n f i r m o r -disprove the e x i s t e n c e of a t h y r o i d d i s e a s e i s the d e t e r m i n a t i o n of the b a s a l m e t a b o l i c r a t e . I n c o n d i t i o n s of h y p e r a c t i v i t y of the t h y r o i d g l a n d , t o t a l metabolism i s a c c e l e r a t e d i n p r o p o r t i o n t o the degree of h y p e r t h y r o i d i s m . A c c o r d i n g t o Hawk and B e r g e i m C ^ , the b a s a l m e t a b o l i c r a t e does not e s t a b l i s h a d i a g n o s i s of h y p e r t h y r o i d i s m , but i n the m a j o r i t y of cases v a r i a t i o n s i n t h e B.M.R.(basal m e t a b o l i c r a t e ) can be i n t e r p r e t e d as v a r i a t i o n s i n t h e f u n c t i o n s of the t h y r o i d g l a n d . A number of d i s e a s e s , d i e t a r y f a c t o r s , and e n v i r o n m e n t a l c o n d i t i o n s w i l l a f f e c t the b a s a l m e t a b o l i c r a t e , b u t , assuming t h a t no o t h e r d i s e a s e s are p r e s e n t , and the e n v i r o n m e n t a l c o n d i t i o n s are conducive t o a b a s a l c o n d i t i o n , a y a r i a t i o n i n the B.M.R. i s i n d i c a t i v e of a t h y r o i d c o n d i t i o n . In o n l y one r e p o r t e d instance(3?) has v i t a m i n B l been r e p o r t e d t o have a l o w e r i n g e f f e c t on the B.M.R. i n a h y p e r t h y r o i d c o n d i t i o n and t h i s c l a i m has been d i s p u t e d ^ ) . The p r e s e n t i n v e s t i g a t i o n was unde r t a k e n t o demonstrate t h e e f f e c t of t h e v i t a m i n s t h i a m i n e ! B l ) , r i b o f l a v i n ( B 2 ) , a n d " p y r i d o x i n e ( B 6 ) , s i n g l y and i n c o m b i n a t i o n , on the b a s a l m e t a b o l i c r a t e of the a l b i n o r a t a f t e r i n d u c e d hyper-t h y r o i d i s m . Metabolism i s regarded as b a s a l when the heat p r o d u c t i o n ^ o f an i n d i v i d u a l i s m i n i m a l , and i s p r e s e n t o n l y under c o n d i t i o n s I n v o l v i n g complete p h y s i c a l and mental r e l a x a t i o n , ,the complete absence of d i g e s t i v e a c t i v i t y , and when the e n v i r o n m e n t a l temperature i s such as t o m i n i m i z e heat p r o d u c t i o n . A survey of, the l i t e r a t u r e r e v e a l e d the f a c t t h a t t h e e x p e r i m e n t a l c o n d i t i o n s under . w h i c h metabolism i s b a s a l have not y e t been w e l l e s t a b l i s h e d f o r s t u d i e s on t h e w h i t e r a t . There i s s t i l l some u n c e r t a i n t y r e g a r d i n g : ( I ) the l e n g t h of the f a s t i n g p e r i o d b e f o r e metabolism i s b a s a l . ( i i ) t h e temperature of t h e r m a l n e u t r a l i t y . ( i i i ) the age of the r a t b e f o r e metabolism i s c o n s t a n t . ( i v ) the i n f l u e n c e of t h e '"diurnal f a c t o r on b a s a l metabolism. These f a c t o r s were i n v e s t i g a t e d , p r i o r and I n c i d e n t a l t o a^study o f the main problem, a l r e a d y s t a t e d . SURVEY I n d i c a t i o n s f o r t h e Use of V i t a m i n Bl,B2,andB6 Supplements i n H y p e r t h y r o i d i s m : a. Weight Loss and A n o r e x i a Among t h e e a r l i e s t i n v e s t i g a t i o n s i n t o the r e l a t i o n s h i p between the B v i t a m i n s and h y p e r t h y r o i d i s m was t h a t of Himwick, Goldf arb ;and C o w g i l l U ^ ) i n 1931. They r e p o r t e d an i n c r e a s e i n t h e requirement of u n d i - f f e r e n t i a t e d v i t a m i n B by the dog d u r i n g i n t e r v a l s of f e e d i n g d e s i c c a t e d t h y r o i d , as determined by t h e p e r i o d of onset of a n o r e x i a and l o s s , of body weight. C o w g i l l a n d • P a l m i e r i ( y ) , u s i n g d e s i c c a t e d t h y r o i d and. H a r r i s y e a s t as a source of v i t a m i n B, f o u n d ' s i m i l a r r e s u l t s w i t h p i g e o n s , i . e . , t h e v i t a m i n B requirement proved t o be g r e a t e r i n h y p e r t h y r o i d ! than under normal c o n d i t i o n s . The p r o t e c t i v e i n f l u e n c e of t h e B v i t a m i n s a g a i n s t weight l o s s and a n o r e x i a due t o t h y r o i d f e e d i n g was f u r t h e r demonstrated by Sure and Smith(#7) i n 1934, u s i n g a l b i n o r a t s . They r e p o r t e d t h a t r e t a r d a t i o n of l o s s of weight can be se c u r e d i n a n i m a l s , r e c e i v i n g t o x i c doses of pure c r y s t a l l i n e t h y r o x i n e ( i n t r a v e n o u s ) , by t h e a d m i n i s t r a t i o n of a potent v i t a m i n B l c o n c e n t r a t e . The i s o l a t i o n of B l i n pure c r y s t a l l i n e f o rm by Merck and Go. made p o s s i b l e a q u a n t i t a i v e study of t h e problem. Sure and Buchanan(^50 found t h a t a dose of 30 t o 100 gammas of pure B i was e f f e c t i v e i n c o u n t e r a c t i n g the t o x i c i t y of as h i g h a d a i l y dose as .2 mg. of t h y r o x i n e . D r i l l and Sherwood(/<?) l i k e w i s e found t h a t t h i a m i n e had an a n t i t h y r o g e n i c e f f e c t I n overcoming a n o r e x i a and weight . l o s s . H y p e r t h y r o i d r a t s * t r e a t e d w i t h v i t a m i n B l and y e a s t , r e g a i n e d l o s t w e i g h t though s t i l l r e c e i v i n g t h e t h y r o i d g l a n d . V i t a m i n B l and y e a s t c o n c e n t r a t e was found t o g r e a t l y s t i m u l a t e t h e f o o d i n t a k e . I n v e s t i g a t i n g t h e c a l o r i c I n t a k e and weight balance of h y p e r t h y r o i d dogs, D r i l l ( / 4 ) found t h a t t h e f o o d i n t a k e of - s i x dogs, on a normal d i e t , i n c r e a s e d t o n e a r l y t w i c e normal when t h y r o i d f e e d i n g was s t a r t e d . A f t e r t h r e e weeks t h e f o o d i n t a k e showed a d e c l i n e , s u g g e s t i n g a d e p l e t i o n o f t h e s t o r e s o f t h e B v i t a m i n s . The i n j e c t i o n . o f B l r e s t o r e d the a p p e t i t e t o the previous- h y p e r t h y r o i d l e v e l , w i t h a r e s t o r a t i o n of weighty When y e a s t was removed from the normal d i e t o f h y p e r t h y r o i d dogs, t h e f o o d i n t a k e dropped s h a r p l y , complete a n o r e x i a r e s u l t i n g i n some c'ases. A l l dogs l o s t w e i g h t , D r i l l ( ^ ) o b t a i n e d the same r e s u l t s w i t h r a t s . Rats f e d BI and t h y r o i d d i d not g a i n weight u n l e s s a r i c h s ource of B2 was added t o the d i e t . D r i l l and Overman(/<£>) r e p o r t e d t h a t t h e i n j e c t i o n of B6 and c a l c i u m pantothenate r e p l a c e d t h i s a d d i t i o n of B2. Thus, i n a d d i t i o n t o t h i a m i n e , p y r i d o x i n e , r i b o f l a v i n and p a n t o t h e n i c a c i d were a l s o f o u n d t o be r e q u i r e d i n l a r g e amounts i n e x p e r i m e n t a l hyper-t h y r o i d i s m . 8. b. G l y c o l y s i s U s i n g a s t a n d a r d d i e t , w i t h y e a s t ©f known v i t a m i n c o n t e n t , D r i l l and Iiays(/5) s t u d i e d t h e l i v e r f u n c t i o n s o'f *dogs at two l e v e l s of t h y r o i d f e e d i n g . In some cases the l i v e r was no r m a l , i n o t h e r s abnormal, when v i t a m i n - B l was p r e s e n t i n the d i e t . I n a l l cases t h e l i v e r was abnormal when the vitam'Ih was absent. D r i i l ( / 7 ) r e p o r t e d t h a t r a t s r e c e i v i n g normal d i e t s c o n t a i n i n g 2.1 t o 2.4 i n t e r n a t i o n a l u n i t s of B l and 2.4 t o 2.6 Sherman-Bourquin u n i t s of v i t a m i n B2 t o g e t h e r w i t h 1 mg. of t h y r o x i n e , s u b c utaneously, p e r day, l o s t weight and showed low l i v e r g l y c o g e n v a l u e s . The same d i e t w i t h o u t t h e t h y r o x i n r e s u l t e d i n weight g a i n s and normal l i v e r g l y c o g e n . Rats f e d a normal d i e t w i t h 54 i n t e r n a t i o n a l u n i t s o f B l and 60 Sherman-Bourquin u n i t s t o g e t h e r w i t h 1 mg. of t h y r o i d -d a i l y g ained weight' o r remained at a c o n s t a n t weight and showed normal l i v e r g l y c o g e n v a l u e s . Mamikawa(5^) demonstrated t h a t the. h e i g h t e n e d . a c t i v i t i e s of t i s s u e r e s p i r a t i o n and g l y c o l y s i s I n the v i s c e r a , i n s t i g a t e d by t h y r o x i n e a d m i n i s t r a t i o n , were weakened f o l l o w i n g the a d m i n i s t r a t i o n of t h y r o x i n supplemented w i t h B l . Kubo {H>l) showed t h a t t h i a m i n e promotes g l y c o g e n e s i s i n h e a l t h y r a b b i t s . T h i s was found t o be marked when t h e stomach was empty. In.some cases o f d i a b e t e s , t h e i n j e c t i o n o f B l a l l e v i a t e d t o a g r e a t e x t e n t 9« the h y p e r g l y c e m i a and g l y c o s u r i a , f o l l o w i n g meals. Supplee,Bender and Hanford(^/3) have r e c e n t l y r e p o r t e d t h a t r a t s d e f i c i e n t i n t h i a m i n e , r i b o f l a v i n , p a n t o t h e n i c a c i d and p y r i d o x i n e show an i n e f f i c i e n t u t i l i z a t i o n of f o o d and i m p a i r e d g l y c o g e n e s i s i n the l i v e r . When animals were d e p l e t e d of any one of thes e and g i v e n the o t h e r s , a r i s e i n the l i v e r g l y c o g e n r e s u l t e d when t h e ' m i s s i n g f a c t o r ' w a s s u p p l i e d . T h i s demonstrated t h a t t h e s e v i t a m i n s a re complementary t o one another and t h a t each may p a r t i c i p a t e i n the b u i l d i n g up of glycogen s t o r e s i n the l i v e r . c» T i s s u e Loss of B l D r i l l i / 3 ) demonstrated t h a t r a t s r e c e i v i n g 12 gm. .of normal d i e t t o g e t h e r w i t h 100 mg. of t h y r o i d g l a n d showed normal amounts o f B l i n t h e s p l e e n , a r e d u c t i o n i n th e k i d n e y and a marked r e d u c t i o n i n the l i v e r , when compared w i t h normal r a t s on the same d i e t . When the d i e t was supplemented w i t h 500•gammas of t h i a m i n e p e r day, t h e r a t s showed normal amounts of B l i n the s p l e e n and muscle, s l i g h t l y more i n the h e a r t and a d e f i n i t e r e d u c t i o n , i n t h e k i d n e y and l i v e r . Both groups e l i m i n a t e d t h e same amount of B l . d. M e t a b o l i s m S c r u t i n i o (38) ha.s r e p o r t e d t h a t v i t a m i n B l , e s p e c i a l l y when i n j e c t e d i n t r a v e n o u s l y , w i l l decrease t h e b a s a l m e t a b o l i c r a t e and i n c r e a s e t h e body weight of 10. h y p e r t h y r o i d p a t i e n t s . J o l l i f e ( 2 6 ) has l i k e w i s e r e p o r t e d an i n c r e a s e d requirement f o r B l when t h e r e i s g r e a t l y augmented metabolism such as o c c u r s i n h y p e r t h y r o i d i s m . On t h e other, h a n d , F r a z i e r and Ra v d i n (o-o) found t h a t B l had no . e f f e c t on t h e B.M.R. of t h y r o t o x i c p a t i e n t s , a l t h o u g h the p a t i e n t s were observed t o g a i n w e i g h t. T o l e r a n c e t o the B V i t a m i n s K l a u s and C l a r k (?/) r e p o r t t h a t the p r o l o n g e d a d m i n i s t r a t i o n of l a r g e amounts of i n d i v i d u a l v i t a m i n s of t h e B group t o r a t s , s u b s i s t i n g on d i e t s e i t h e r e n t i r e l y f r e e from o r p a r t l y d e f i c i e n t ' i n one or more f a c t o r s of the B complex, f a i l e d t o aggravate m a n i f e s t a t i o n s of t h e d e f i c i e n c y . R e garding t h e t o l e r a n c e of r a t s t o l a r g e doses o f the B v i t a m i n s , Kuhn (2>?) s t a t e s t h a t the a d m i n i s t r a t i o n of one thousand times t h e p h y s i o l o g i c a l requirement o f B2 d i d not cause i n j u r y . Demole ( 2 - ^ ) a l s o observed t h a t r a t s d i d not s u f f e r i n j u r y from doses as l a r g e a s . f i v e thousand t i m e s the p r o t e c t i v e l e v e l of the B v i t a m i n s . V i t a m i n B l has been g i v e n t o normal humans i n doses of ;S00 mg. ( 150,000 I.U.) d a l l y - w i t h o u t any untoward e f f e c t s ). S t e i n b e r g (^z-) r e p o r t s t o x i c a c t i o n i n l e s s t han one p e r c e n t of. h i s cases t r e a t e d w i t h massive doses of B l . S y d e n s t r i c k e r , G e e s l i n , T e m p l e t o n and Weaver {*/<f ) r e p o r t t h a t r i b o f l a v i n a d m i n i s t e r e d i n d a i l y doses as h i g h as 3 mg. i n t r a m u s c u l a r l y , 25 mg. i n t r a v e n o u s l y , 50 mg. subcutaneously and 60 mg. o r a l l y produced no i l l e f f e c t s on humans. O r a l and i n t r a v e n o u s doses of 100 t o 200 mg. of p y r i d o x i n e were found by Weigand,Eckler and Chen (5"'/-) t o produce no untoward symptoms i n humans, a l t h o u g h p a i n was r e p o r t e d i n some cases a f t e r i n t r a m u s c u l a r i n j e c t i o n s . F a c t o r s Governing t h e B a s a l M e t a b o l i c . Rate . a. F a s t i n g I n g e n e r a l v m o s t workers have f o l l o w e d the r u l e t h a t the metabolism- i s b a s a l i n a l b i n o r a t s , a f t e r e i g h t e e n hours f a s t i n g . B e n e d i c t and Mac L e o d . ( ^ ) found t h a t t he B.M.R. of t h e f a s t i n g r a t dropped from c e s s a t i o n of f e e d i n g t o the I 7 t h hour p o s t - a b s o r p t i o n and t h e r e a f t e r remained e s s e n t i a l l y c o n s t a n t t o the 6 4 t h hour p o s t - a b s o r p t i o n . With r a t s f o u r and o n e - h a l f months i n age, B e n e d i c t and MacLeod o b t a i n e d a decrease' of a p p r o x i m a t e l y 10$ i n the f i r s t twenty f o u r hours a f t e r f e e d i n g . Wesson (5"?-) found t h a t • th e B.M.R. o f the f a s t i n g r a t i n c r e a s e s from t h e 1 4 t h t o the 24t h hour p o s t - a b s o r p t i o n and su b s e q u e n t l y d r o p s , r e a c h i n g a l e v e l a t t h e 32nd hour. Kingdon,Bunnel and G r i f f i t h s i p o ) found t h a t t h e maximal heat p r o d u c t i o n o c c u r r e d d u r i n g the f i r s t hour a f t e r f e e d i n g stopped. Making h o u r l y d e t e r m i n -a t i o n s from t h e f i r s t hour a f t e r f e e d i n g , they observed t h a t the m e t a b o l i c r a t e d e c l i n e d d u r i n g the f i r s t twenty hours and t h e n showed a sharp r i s e t o the 24th hour, 12. f o l l o w e d by a drop t o the 36th hour p o s t - a b s o r p t i o n , b. E n v i r o n m e n t a l Temperature B e n e d i c t and MacLeod {if ) made d e t e r m i n a t i o n s over a temperature range of from 10 C to 32 G of the b a s a l m e t a b o l i c r a t e s of a l b i n o r a t s . They r e p o r t e d t h a t t h e b a s a l metabolism was lowered as the temperature I n c r e a s e d up t o 28 C. Above t h i s t e mperature, they found t h a t t t h e -basair-metabolism became c o n s t a n t . S w i f t and Forbes ( f ? ) t e s t e d r a t s by submerging them,in f o u r - l i t e r j a r s f i l l e d w i t h a i r , I n water b a t h s a t v a r i o u s t e m p e r a t u r e s . The e f f e c t o f temperature on t h e B.M.R. was s t u d i e d over a range of from 7.5 G t o 35 G. They r e p o r t e d t h a t t h e c r i t i c a l temperature was somewhat h i g h e r ( 30 C) t h a n B e n e d i c t and MacLeod had found. H e r r i n g t o n (5-3) s t a t e d t h a t t h e r m a l n e u t r a l i t y f o r the a l b i n o r a t occurs between 28 C and 29 C. c. Time.of Day Horst,Mendel,and B e n e d i c t ( 2 f ) r e p o r t e d t h a t the b a s a l metabolism of the r a t i s s u b j e c t t o d i u r n a l v a r i a t i o n . The oxygen consumption was found t o be h i g h i n the morning a n d . l a t e a f t e r n o o n but low a t midday. U s i n g f o u r - r a t s , they found t h a t t h e v a l u e s o b t a i n e d i n the e a r l y morning and l a t e a f t e r n o o n were from 13 t o 50$ g r e a t e r d u r i n g these p e r i o d s than a t midday. On the b a s i s of t h e s e r e s u l t s , they recommended t h a t b a s a l metabolism.measurements s h o u l d be c o n f i n e d t o t h e p e r i o d between 10 A.M. and 4 P.M., s i n c e d u r i n g t h i s p e r i o d , heat p r o d u c t i o n i s more b a s a l . 13. d. Age Davi s ( 10 ) and Davis and Ha s t i n g s (// ) found t h a t the oxygen consumption per k i l o g r a m weight o f r a t s f a l l s r a p i d l y d u r i n g t h e f i r s t f o u r months and more s l o w l y t h e r e a f t e r . G u l i c k (>/ ) r e p o r t e d t h a t t h e B.M.R. i n c r e a s e s d u r i n g t h e f i r s t f i v e weeks a f t e r " b i r t h , reaches t h e maximum i n t h e s i x t h week and su b s e q u e n t l y f a l l s t o approach normal. K e s t n e r (2.7 ) and Blank ( 5" ) b e l i e v e d t h a t t h e h i g h e r m e t a b o l i c r a t e per u n i t weight observed i n s m a l l animals cannot be a s c r i b e d t o the r e l a t i v e l y l a r g e r s u r f a c e area,but r a t h e r t o the p r o p o r t i o n of a c t i v e m e t a b o l i c t i s s u e . e. B a r o m e t r i c P r e s s u r e Wesson (5V) has r e p o r t e d t h a t t h e v a r i a t i o n s i n the b a s a l m e t a b o l i c r a t e due t o changes i n t h e b a r o m e t r i c p r e s s u r e have no a p p r e c i a b l e e f f e c t on the r e s p i r a t o r y gas exchange and c a n , t h e r e f o r e , b e e l i m i n a t e d from b a s a l m e t a b o l i c d e t e r m i n a t i o n s . / T h y r o i d P r e p a r a t i o n s and Manner of A d m i n i s t r a t i o n Barnes and Bueno ( 7- ) found t h a t t h e B.M.R. i n c r e a s e d from 30% t o 40% i n dogs f o l l o w i n g t h e i n j e c t i o n of t he p i t u i t a r y t h y r e o t r o p h i c hormone. T h i s e f f e c t was a t t r i b u t e d t o s t i m u l a t i o n of the t h y r o i d g l a n d s i n c e t h y r o i d e c t o r a l z e d dogs showed no response. The d a i l y a d m i n i s t r a t i o n of d e s i c c a t e d t h y r o i d , c o n t a i n i n g an amount o f i o d i n e e q u i v a l e n t t o a l l the i o d i n e i n t h e g l a n d , 14. f a i l e d t o r a i s e the B.M.R. as much as t h e t h y r e o t r o p h i c hormone. I t was suggested t h a t t h y r o g l o b u l i n , s e c r e t e d by the g l a n d , i s much more e f f e c t i v e t h a n a d m i n i s t e r e d t h y r o i d p r o d u c t s . A c c o r d i n g l y , a study was made t o compare t h e r i s e i n t h e B'.M.R. due t o t h y r o i d p r e p a r a t i o n s , g i v e n s u b c u t a n e o u s l y and o r a l l y . F i v e dogs were t r e a t e d and r e a c t e d i n the same way. The subcutaneous i n j e c t i o n s proved f o u r .to f i v e t i m e s more e f f e c t i v e than the o r a l l y a d m i n i s t -ered t h y r o i d . T h i s i n d i c a t e d t h a t t he t h y r o i d hormone, s i m i l a r t o o t h e r hormones, l o s e s c o n s i d e r a b l e a c t i v i t y i n the a l i m e n t a r y c a n a l . S a l t e r (3d?) r e p o r t e d t h a t the hormone i s decomposed in- the g a s t r o - i n t e s t i n a l t r a c t , b e i n g o n l y 6 2 % as potent a d m i n i s t e r e d o r a l l y as i n t r a v e n o u s l y . Cooper ( y ) found t h a t t h e o r a l a d m i n i s t r a t i o n of s i n g l e doses of o n e - t e n t h , o n e - f i f t h and o n e - h a l f g r a i n d e s i c c a t e d t h y r o i d t o t h e w h i t e r a t , p r e v i o u s l y f a s t e d t w e n t y - f o u r h o u r s , r e s u l t e d i n a marked r e d u c t i o n i n t h e B.M.R. f o r s e v e r a l hours f o l l o w i n g t h e a d m i n i s t r a t i o n of the d r u g . T h i s r e d u c t i o n became l e s s marked as the t h y r o i d dose i n c r e a s e d i n potency. Kunde (33) found t h a t no s i g n i f i c a n t change i n the B.M.R. o c c u r r e d f o r seven t o t w e l v e hours a f t e r a s i n g l e dose o f K e n d a l l ' s t h y r o x i n was a d m i n i s t e r e d i n t r a -v e nously o r d e s i c c a t e d t h y r o i d , o r a l l y , t o dogs. He observed an a p p r e c i a b l e I n c r e a s e i n t h e heat p r o d u c t i o n on t h e day f o l l o w i n g the a d m i n i s t r a t i o n of the hormone. He a l s o 15. found t h a t a f t e r r e p e a t e d d a i l y doses of e i t h e r t h y r o i d or t h y r o x i n e , t h e b a s a l m e t a b o l i c r a t e p r o g r e s s i v e l y i n c r e a s e d , r e a c h i n g a maximum i n t h r e e weeks. He s t a t e d t h a t a q u a n t i t a t i v e r e l a t i o n s h i p between t h e t h y r o i d i n g e s t e d and the B.M.R. does not e x i s t . 16. EXPERIMENTAL Animals T h i r t y a l b i n o r a t s , male and female, were used i n t h i s i n v e s t i g a t i o n , a l l r a t s b e i n g t h e P I progeny o f f o u r a nimals o b t a i n e d from t h e W i n s t a r I n s t i t u t e , P h i l a d e l p h i a . Environment ,• The r a t s were housed i n a room measuring a p p r o x i m a t e l y 8 f t . by 6 f t . by 6 f t . The temperature of t h e room was t h e r m o s t a t i c a l l y c o n t r o l l e d a t 76 F,and the r e l a t i v e ^ h u m i d i t y , was 45 t o 50%. The room was f r e e from d r a f t s and v e n t i l a t e d by drawing i n f r e s h a i r from the o u t s i d e . Two 60 watt b u l b s p r o v i d e d i l l u m i n a t i o n , auto-m a t i c a l l y c o n t r o l l e d by a time c l o c k t o g i v e t e n hours l i g h t per day. The r a t cages were c o n s t r u c t e d of g a l v a n i z e d m e t a l , each w i t h s o l i d ' s i d e s and back, and a w i r e t o p , bottom and f r o n t . Each cage was equipped w i t h a d r o p p i n g pan f i l l e d w i t h f i n e sawdust t o absorb m o i s t u r e and t o f a c i l i t a t e c l e a n i n g . The cages were c l e a n e d each week and then sprayed w i t h l y s o l . Water was s u p p l i e d from erlenmeyer f l a s k s , i n v e r t e d and f a s t e n e d i n f r o n t of t h e cage, w i t h a bent g l a s s tube p r o j e c t i n g i n t o t h e cage t o serve as an o u t l e t tube. The r a t s were q u a r t e r e d two or t h r e e t o a.cage. 17. F o r the work on v i t a m i n s , i t was found expedient t o i s o l a t e the a n i m a l s , p l a c i n g them one t o a cage. D i e t Throughout the i n v e s t i g a t i o n the r a t s were g i v e n water ad l i b i t u m . The r a t s were f e d once each day, a d a i l y , r a t i o n , p e r r a t , c o n s i s t i n g of from two t o t h r e e checkers of s p e c i a l l y p r e p a r e d f o o d . These checkers were s u p p l i e d by the P u r i n a M i l l s , S t . L o u i s , M o . , under the t r a d e name of " P u r i n a Fox Chow", and were s t a t e d t o c o n t a i n : f l a v i n c o n c e n t r a t e a l f a l f a meal caro t e n e c o r n g r i t s wheat germ soybean meal d r i e d skim m i l k molasses l i v e r meal d r i e d beet pulp , brewer's d r i e d y e a s t cod l i v e r o i l b a r l e y malt 1% steamed bone meal f i s h meal 1% i o d i z e d s a l t , d r i e d meat Compared t o t h e known n u t r i t i o n a l r e q u i r e m e n t s of t h e l a b o r a t o r y r a t , an a n a l y s i s of t h e P u r i n a checkers by t h e P u r i n a L a b o r a t o r i e s showed t h a t a p p r o x i m a t e l y two ti m e s t h e v i t a m i n requirements a re p r e s e n t . Source of T h y r o x i n e and V i t a m i n s The f o l l o w i n g drugs were used: 1. One-tenth g r a i n d e s i c c a t e d t h y r o i d , t h e product of Burroughs Wellcome & Co. Each t a b l e t i s s t a t e d t o r e p r e s e n t o n e - t e n t h grain(,0065gm.) of f r e s h h e a l t h y g l a n d substance, e q u i v a l e n t t o l / 3 3 r d g r a i n t h y r o i d ? The i o d i n e c o ntent i s 0.1$. 2. One-tenth g r a i n d e s i c c a t e d t h y r o i d , t h e product of 18. Parke,Davis & Co. Each t a b l e t r e p r e s e n t s one-tenth g r a i n t h y r o i d , c o n t a i n i n g 0.3% i o d i n e . 3. One-quarter g r a i n d e s i c c a t e d t h y r o i d ( B u r r o u g h s Wellcome & Co.). Each t a b l e t r e p r e s e n t s o n e-quarter g r a i n ( l 6 mgm.) of f r e s h h e a l t h y g l a n d substance, e q u i v a l e n t t o 8/40ths d r y t h y r o i d , B . P . The i o d i n e c o n t e n t i s 0.25% . 4. V i t a m i n B l ( t h i a m i n e h y d r o c h l o r i d e ) . Each dose c o n s i s t e d of 1 mg., e q u i v a l e n t t o 333 i n t e r n a t i o n a l u n i t s o r 333 U.S.P. u n i t s . Product of the B r i t i s h Drug Houses, L t d . (B.D.H.). 5. V i t a m i n B2 ( r i b o f l a v i n ). Each dose c o n s i s t e d of 1 mg., e q u i v a l e n t t o 400 Sherman-Bourquin u n i t s . A product of the B r i t i s h Drug Houses, L t d . (B..D.H.). 6. V i t a m i n B6 ( p y r i d o x i n e h y d r o c h l o r i d e ). Each dose c o n s i s t e d of 1 mg. o r 1000 micrograms(gammas). No commonly acc e p t e d b i o l o g i c u n i t i s g i v e n . The product o f E l i L i l l y & Co., and s o l d c o m m e r c i a l l y as H e x a b e t a l i n . The above drugs were a d m i n i s t e r e d w i t h t h e f o o d . A normal d a i l y r a t i o n of t h e che c k e r s ( a p p r o x i m a t e l y 18 gms. was p u l v e r i z e d i n a m o r t a r , admixed as homogeneously as p o s s i b l e v/ith t h e drug used, and reformed i n t o a checker by a d d i n g a l i t t l e w a t e r , and a l l o w i n g the p a s t y m i x t u r e t o d r y . S i n c e r i b o f l a v i n i s p h o t o l i t h i c , care was t a k e n t o prevent i t s d e c o m p o s i t i o n by t h e l i g h t . A l l d i e t s which c o n t a i n e d the drugs were prepared i m m e d i a t e l y b e f o r e f e e d i n g t i m e . 19. Apparatus a. M o d i f i c a t i o n s from t h e O r i g i n a l Design The apparatus used was .designed by E.L.Schwabe and F . R . G r i f f i t h , J r . (itf ),at the U n i v e r s i t y of B u f f a l o , t o determine "basal metabolism by the method of i n d i r e c t c a l o r i m e t r y . C e r t a i n m o d i f i c a t i o n s vrere made i n the apparatus by W.Cooper (V ) / a t the U n i v e r s i t y o f B r i t i s h Columbia, i n the 'manner o f removing the carbon d i o x i d e and o f r e g i s t e r i n g the oxygen consumption. I n s t e a d of u s i n g a s t a n d a r d i z e d s o l u t i o n of barium h y d r o x i d e and b r i n g i n g t h e chamber a i r ' . i n c o n t a c t w i t h t h i s , t o e f f e c t the removal of carbon d i o x i d e Cooper employed soda l i m e . The animal chamber c o n s i s t e d o f two p a r t s , an a b s o r p t i o n u n i t c o n t a i n i n g - t h e soda l i m e , and a wide g l a s s v e s s e l , a p p r o x i m a t e l y 9-|- i n c h e s i n d i a m e t e r , which f i t t e d over the a b s o r p t i o n u n i t . T h i s u n i t c o n s i s t e d of a round wooden d i s c , 8f- i n c h e s i n diamet-er and -J- i i t c h e s t h i c k . The soda l i m e was p l a c e d between w a l l s of copper gauze, concent-r i c a l l y p l a c e d around t h e o u t s i d e of t h e c i r c u l a r p i e c e of wood and f i r m l y cemented t o i t . The w a l l s were 2-jr i n c h e s h i g h and § i n c h e s a p a r t . The a b s o r p t i o n u n i t h e l d a p p r o x i m a t e l y 400 grams of soda l i m e . The base of t h e chamber was a t h i n copper p l a t e i n w h i c h was impressed a c i r c u l a r t r o u g h t o f i t the r i m of the. g l a s s v e s s e l . When i n use, t h i s t r o u g h was p a r t l y 20. f i l l e d w i t h mercury, thus e n s u r i n g an a i r - t i g h t s e a l f o r the a n i m a l chamber. An i n l e t tube from the apparatus p e n e t r a t e d t h i s copper p l a t e and passed i n t o the animal chamber through a h o l e b o r e d i n . t h e wooden base o f ' t h e a b s o r p t i o n u n i t . . The soda l i m e was found t o g i v e s a t i s f a c t o r y r e s u l t s f o r about f i f t y twenty-minute r u n s , a f t e r which i t s - e f f i c i e n c y c o u l d not be r e l i e d upon. The second m o d i f i c a t i o n c o n s i s t e d i n s u b s t i t u t i n g a h e a v i e r f l o a t i n the water manometer i n p l a c e of the l i g h t p a r a f f i n e d c o r k Yfhich was used to support the bamboo r o d and w r i t i n g p o i n t . Cooper found t h a t s l i g h t v i b r a t i o n s i n t h e apparatus were t r a n s m i t t e d t o the c o r k f l o a t c a u s i n g f l u c t u a t i o n s I n t h e graph. R e p l a c i n g t h i s l i g h t f l o a t by a h e a v i e r g l a s s f l o a t r e d u c e d the s e n s i t i v i t y and e l i m i n a t e d t h e f l u c t u a t i o n s , r e c o r d i n g the r i s e i n the manometer l e v e l w i t h t h e same f i d e l i t y but w i t h a smmother c u r v e . In t h e o r i g i n a l d e s i g n , t h e animal chamber was . p l a c e d above th e animal's oxygen s u p p l y . S i n c e the a i r i n the chamber was made t o c i r c u l a t e i n o r d e r t o e x p e d i t e the removal of carbon d i o x i d e and i t s a b s o r p t i o n by the barium h y d r o x i d e , some d e v i c e was found n e c e s s a r y - t o prevent the d i f f u s i o n of t h e carbon d i o x i d e back i n t o the apparatus. For t h i s reason a M u l l e r v a l v e was i n s t a l l e d on the i n t a k e l i n e c o n n e c t i n g t h e apparatus w i t h t h e a n i m a l chamber.. However, s i n c e the a b s o r p t i o n u n i t , as m o d i f i e d by Cooper, 21. was contained, w i t h i n the a n i m a l chamber, and s i n c e the animal chamber i t s e l f c o u l d be c o n v e n i e n t l y p l a c e d a t some d i s t a n c e below the oxygen s u p p l y i n t h e a p p a r a t u s , the M i i l l e r v a l v e was, f o r a l l p r a c t i c a l purposes, deemed u n e s s e n t i a l . . S l i g h t p r e s s u r e changes r e g i s t e r e d by the o i l manometers p l a c e d on t h e two s i d e s of the M u l l e r v a l v e i n d i c a t e d t h a t some s u c t i o n was r e q u i r e d t o draw the oxygen through t h i s v a l v e . Since a s l i g h t source of e r r o r would r e s u l t from t h i s f o r c i b l e s u c t i o n , and s i n c e the v a l v e was no l o n g e r e x p e d i e n t f o r i t s p r i m a r y f u n c t i o n , i t was. removed from t h e a p p a r a t u s . A diagram of the apparatus i s ; p r e s e n t e d on page 22. For a d e t a i l e d d e s c r i p t i o n of the a p p a r a t u s , r e f e r e n c e i s g i v e n t o the p u b l i s h e d r e p o r t of Schwabe and G r i f f i t h (3.7) and t o the..reports of K i l b a n k i z l ) and Cooper ( 7 ) . 23. b. O p e r a t i o n of the Apparatus A f t e r the r a t i s p l a c e d i n t h e chamber, and the g l a s s top of the animal chamber i s p r e s s e d f i r m l y down i n the mercury t r o u g h t o ensure an a i r - t i g h t s e a l , the apparatus i s ' f l u s h e d w i t h oxygen, s u p p l i e d to the apparatus from a commercial c y l i n d e r of the gas. As the animal r e s p i r e s , and carbon d i o x i d e and m o i s t u r e are absorbed by the .soda l i m e , oxygen d i f f u s e s i n t o t h e chamber from the erlenmeyer f l a s k (G - r e f e r t o diagram,p.22) t o m a i n t a i n a u n i f o r m i n t e r n a l gaseous p r e s s u r e . The gaseous p r e s s u r e w i t h i n the erlenmeyer f l a s k and the animal chamber i s kept at atmospheric p r e s s u r e by a l l o w i n g water t o s i p h o n i n from c y l i n d e r D as oxygen i s drawn out from f l a s k ( G ) . C y l i n d e ( D ) i s connected t o t h e manometer s y s t e m ( J ) c o n t a i n i n g t h e g l a s s f l o a t (K) and w r i t i n g , p o i n t ( L ) . The gaseous p r e s s u r e i n the t u b e c o n n e c t i n g c y l i n d e r (D) t o t h e manometer system i s l e s s t h a n atmospheric. Thus the w a t e r l e v e l i n the open arm of the water manometer i s lower t h a n t h a t i n the e n c l o s e d arm. As water siphons over from c y l i n d e r D to f l a s k G, oxygen bubbles i n t o D from the rubber b l a d d e r ( C) t h r o u g h tube x. Consequently the gaseous p r e s s u r e above t h e e n c l o s e d arm of t h e water manometer g r a d u a l l y r e t u r n s t o atmospheric as t h e water l e v e l i n D i s lowered. W i t h i n c r e a s i n g p r e s s u r e i n the e n c l o s e d arm o f the manometer, the water l e v e l i n the open arm r i s e s , c a u s i n g t h e kymograph needle (L) t o r i s e . Thus th e oxygen consumed by 24. the r a t can be computed from t h e v e r t i c a l r i s e of the kymograph n e e d l e . When a r u n i s s t a r t e d , the kymograph drum i s so p l a c e d t h a t t h e w r i t i n g - p o i n t r e s t s d e l i c a t e l y a g a i n s t the smoked graph paper. The drum i s then spun so t h a t a b a s e l i n e i s t r a c e d a g a i n s t t h e graph from which the v e r t i c a l r i s e o f t h e needle can be meastired. The drum i s a t t a c h e d t o a c l o c k geared t o make one r e v o l u t i o n i n t h i r t y minutes. At the con-clusion o f t h e r u n , t h e graph paper i s d i p p e d i n v a r n i s h , mixed w i t h t u r p e n t i n e , t o p r e s e r v e i t and then suspended over a t r o u g h u n t i l d r y . The procedure f o r m a n i p u l a t i n g the v a l v e s i s , b r i e f l y , as f o l l o w s : a. To operate apparatus( assuming a l l v a l v e s t o be c l o s e d ) 1. a f t e r t h e animal has been p l a c e d i n t h e chamber, as d e s c r i b e d , open v a l v e s 12,8,9,10 and 11. Valve 9 need never be c l o s e d . 2. when C i s p a r t l y i n f l a t e d , c l o s e 12. 3. d e f l a t e C g e n t l y t o f l u s h G and P. 4. c l o s e v a l v e s 11,8 and 10( when the o i l manometer r e g i s t e r s equal i n t e r n a l and e x t e r n a l p r e s s u r e . 5. r e s t t h e w r i t i n g p o i n t d e l i c a t e l y a g a i n s t the graph paper and s p i n t h e drum t o o b t a i n a b a s e l i n e . 6. open v a l v e s 7,1 and 5. The apparatus i s now i n o p e r a t i o n . 213 & b. To d i s c o n t i n u e the r u n , 1. c l o s e v a l v e s 1,7 and 5. 2. open v a l v e s 8 and 11 3. the animal may now be removed from the chamber c. To r e s e t t h e a p p a r a t u s , 1. c l o s e a l l v a l v e s , w i t h t h e e x c e p t i o n of 9 and 2. open v a l v e s 2,3 and 6. 3. when the water i n c y l i n d e r D has r e t u r n e d to l e v e l z, c l o s e v a l v e s 2,3 and 6. d. To r e s e t the- l e v e l l i n g b u l b s , 1. r e f i l l l e v e l l i n g bulb.B by e l e v a t i n g b u l b A above B and opening v a l v e s 3 and 4. 2. shut v a l v e s 3 and 4 and r e t u r n b u l b A t o i t s former p o s i t i o n . Measurement of t h e B a s a l M e t a b o l i c Rate Newton's Law t h a t the r a t e o f c o o l i n g o f a body depended on I t s s i z e suggested t o Bergman (1847) t h a t a r e l a t i o n s h i p e x i s t e d between the s u r f a c e a r e a of an animal and I t s heat p r o d u c t i o n . T h i s i s the b a s i s f o r most formulae used I n computing the b a s a l m e t a b o l i c r a t e s today. The b a s a l m e t a b o l i c r a t e may be expressed as the r a t i o o f t h e c a l o r i c v a l u e of t h e oxygen consumed i n a g i v e n t i m e , t o t h e ' s u r f a c e a r e a o f the a n i m a l . B e n e d i c t (3 ) s t a t e d t h a t i t may be assumed t h a t the r e s p i r a t o r y q u o t i e n t of a r a t which has been twenty f o u r hours w i t h o u t f o o d i s c l o s e t o .72 . On t h i s assumption he has shown t h a t l i t t l e e r r o r i s i n t r o d u c e d i f oxygen alone i s determined and the heat p r o d u c t i o n c a l c u l a t e d from t h i s . A c c o r d i n g t o Lusk ( 3 4 ) t h e c a l o r i c v a l u e o f one l i t e r of oxygen a t S.T.P. when the R.Q.. i s .72 i s 4.702 c a l o r i e s . Tp o b t a i n the c a l o r i c v a l u e of t h e oxygen consumed, t h e volume o f oxygen consumed i n t e n minutes ( o b t a i n e d from graph) i s co n v e r t e d t o one hour and c o r r e c t e d f o r temperature. The c o r r e c t e d volume i n l i t r e s , m u l t i p l i e d by 4.702 g i v e s t h e c a l o r i c v a l u e of t h e oxygen consumed i n one hour. A number o f formulae e x i s t f o r e s t i m a t i n g the s u r f a c e a r e a o f t h e r a t . A l i s t of thes e formulae has been g i v e n by Cooper ( 7 ). Since t h e d i f f e r e n t formulae show l i t t l e agreement i n t h e B.M.R. v a l u e s o b t a i n e d , and s i n c e i t was d e s i r e d t o c o r r e l a t e c e r t a i n B.M.R. v a l u e s w i t h r e s u l t s o b t a i n e d by Cooper, t h e f o r m u l a -adopted h e r e i s . . . . . . . . . . . . 2 / t h a t o f Rubner, i . e . , the S u r f a c e A r e a equals 9.1 x Weight The s u r f a c e a r e a o b t a i n e d by t h i s f o r m u l a i s d i v i d e d by 10,000 t o c o n v e r t i t t o square meters. Thus t h e v a l u e f o r t h e b a s a l m e t a b o l i c r a t e i s e x p r e s s e d as c a l o r i e s p e r square meter per hour. A sample c a l c u l a t i o n f o l l o w s . f i g . 2. Diagrammatic r e p r e s e n t a t i o n o f a graph To i n t e r p r e t t h e graph, r e p r e s e n t e d by f i g . 2 on t h e f o r e g o i n g page, i t i s r e q u i r e d t o know t h e h o r i -z o n t a l d i s t a n c e t r a v e r s e d i n a u n i t t i m e , and a l s o t o know the oxygen consumption r e p r e s e n t e d by the v e r t i c a l r i s e above t h e b a s e l i n e . T h i s c a l i b r a t e d d a t a was found t o be: 1 cm. r i s e - 23.47 c c s . of oxygen 1 cm. h o r i z o n t a l - .625 minutes She oxygen consumption f o r a t e n minute p e r i o d was found by measuring a l o n g the b a s e l i n e a d i s t a n c e o f 16 cm.- from t h e point, at which i t i s i n t e r s e c t e d by t h e graph. ;The v e r t i c a l h e i g h t from t h i s p o i n t t o the.graph, i s . t h e n measured. T h i s v e r t i c a l d i s t a n c e m u l t i p l i e d by the v o l u m e t r i c e q u i v a l e n t o f t h e manometer (23.47 c c s . ) g i v e s t h e oxygen consumption f o r a t e n minute run. I f the graph, i s not s t r a i g h t , then'a b a s a l p o r t i o n of t h e curve s h o u l d be s e l e c t e d , i . e . where the curve shows the l e a s t i n c l i n a t i o n t o the b a s e l i n e . U s i n g p a r a l l e l r u l e r s , the b a s e l i n e may t h e n be moved up o r down as the o c c a s i o n demands. L e t us assume t h e v e r t i c a l r i s e i s 1.75 and the weight of t h e r a t i s 170( r a t £100, tablefcfe). The temperature i s 28° C. The b a s a l m e t a b o l i c r a t e i s c a l c u l a t e d as f o l l o w s : 28. 25.47 x ,1.75 x 60 x 273 x 4.702 x 1000 ~ 27T-T — M u l K b y V » l . c o n s u m e d C o n v e r t e d C o r r e c t e d Caloric value i n ( O m i n u t e s t o h o u r s f o r Tump- o f i l i t e r of- Oxy^<tn T/3 -=37.3 cals/m^hr 9.1 x W 10,000 ' Divided by tht •sor-poce. a<r-ea o f r«e Methods Employed v a. F a c t o r s I n f l u e n c i n g the B.M.R, 1. L e n g t h of f a s t i n g Pour r a t s ( t h e number employed by Eingdon, Bunnel and G r i f f i t h ), two o f each sex, were used i n the f i r s t experiment, which was 'commenced at 9 A.M. and conc l u d e d at 3 P.M. the f o l l o w i n g day, continuous d e t e r m i n a t i o n s of t h e B.M.R. b e i n g made at i n t e r v a l s o f s i x h o u r s . The r a t s were f e d p r i o r t o t h e experiment, t h e f o o d b e i n g removed at 9 A.M. Between d e t e r m i n a t i o n s o f t h e B.M.R., t h e r a t s were p r o v i d e d w i t h water and p e r m i t t e d normal a c t i v i t y . The en v i r o n m e n t a l temperature throughout the experiment was between 25 C and 31 G. At t h i s temp-e r a t u r e , however, l i t t l e a c t i v i t y was d i s p l a y e d . P r i o r t o each r u n the a n i m a l was .weighed. ( c f . Table l a , g r a p h i c ) Prom the r e s u l t s o b t a i n e d i n the f i r s t experiment, i t f e l t d e s i r a b l e t o r e p e a t the experiment from the 18 t h 29. hour onwards, making h o u r l y d e t e r m i n a t i o n s . Pour males and t h r e e females were f a s t e d from 18 t o 21 hours and e x p e r i -mental runs made each hour up t o 27 ho u r s . The experiment was conducted a t 28°G, no time b e i n g a l l o w e d f o r the animals t o a d j u s t t o the h i g h e r temperature. ( c f . T a b l e l b , graph!b) 2. E n v i r o n m e n t a l Temperature S i x a n i m a l s , two males and f o u r females were t e s t e d on f o u r s u c c e s s i v e d a y s , a f t e r f a s t i n g p e r i o d s of 20 h o u r s , a t temperatures o f 21°C, 27°C, 31.5°C and 39°C, t o determine the e f f e c t of envi r o n m e n t a l temperature on the B.M.R. of t h e f a s t i n g r a t . By t h i s stage i n the work the apparatus had been removed to a s m a l l g l a s s e d - i n room, measuring a p p r o x i m a t e l y 5 f t . by 7 f t . The room was heated by a s m a l l h e a t e r c o n t a i n i n g two e l e c t r i c c o i l s , one o f wh i c h was under t h e r m o s t a t i c c o n t r o l . The o t h e r c o i l served t o reduce the time r e q u i r e d t o b r i n g the room to the d e s i r e d t e mperature, a t which t i m e t h i s c o i l was c u t out. B e f o r e t h e a c t u a l determinations:we're made,/the animals were p l a c e d i n t h e room f o r a p e r i o d - o f from one t o two hours i n or d e r t o a d j u s t themselves m e t a b o l i c a l l y t o the change.in t h e env i r o n m e n t a l temperature. ( c f . T a ble 2-, graph % ) 3. Age As t h e survey shows, the B.M.R. o f t h e young r a t has been observed t o r i s e s h a r p l y d u r i n g t h e f i r s t s i x weeks, p o s t - n a t a l , l e v e l s o f f , and from t h e seventh week onwards d e c l i n e s t o t h e f o u r t h month a f t e r which the B.M.R* i n the 50. h e a l t h y a n imal remains more o r l e s s s t a t i o n e r y up t o two -ye a r s . I t was d e s i r e d to a s c e r t a i n the e a r l i e s t age at which the B.M.R. becomes c o n s t a n t , so t h a t a v a r i a t i o n from t h i s B.M.R. would denote the e f f e c t o f some superimposed f a c t o r such as d e s i c c a t e d t h y r o i d and not the e f f e c t of age and growth. Pour r a t s , two males and two fe m a l e s , were used. The animals were f a s t e d 24 h o u r s - p r i o r i?o t h e experiments, which were c a r r i e d out at a temperature of a p p r o x i m a t e l y 28 degrees C e n t i g r a d e . The d e t e r m i n a t i o n s were made a t i n t e r v a l s of seven days throughout t h e e x p e r i m e n t a l p e r i o d , b e g i n n i n g a t the s i x t h week and c o n t i n u i n g t o the t w e l f t h week. Values were a g a i n o b t a i n e d a f t e r seven months. ( c f . T a b l e d graph.3 ) 4. l i m e o f day Pour r a t s ( t h e same number used by Horst,Mendel and B e n e d i c t ) , t h r e e males and one female from t h e same l i t t e r , were used t o t e s t t h e d i u r n a l e f f e c t on the b a s a l m e t a b o l i c r a t e . The r a t s were f a s t e d f o r 24 hours and d e t e r m i n a t i o n s made a t a temperature of 28°C. D e t e r m i n a t i o n s were made at , 10 A.M., 12 A.M. and 4 P.M. ( c f . T a b l e H , g r a p h H ) b. D e s i c c a t e d T h y r o i d 1. A d m i n i s t e r e d a f t e r F a s t i n g Cooper (7 ) found t h a t the o r a l a d m i n i s t r a t i o n of graded s i n g l e dpses of Burroughs WeTlcome Co. d e s i c c a t e d t h y r o i d g l a n d ( l / l O t h , l / 5 t h and l / 2 g r a i n ) t o t e n r a t s f a s t e d 24 hou r s , produced a marked r e d u c t i o n i n the B.M.R., measured h o u r l y f o r s i x hours a f t e r the a d m i n i s t r a t i o n of 31. the drug. S i n g l e d e t e r m i n a t i o n s made at i n t e r v a l s o f 24 hours t h e r e a f t e r f o r one week f a i l e d t o show any i n c r e a s e i n the B.M.R. over t h e i n i t i a l b a s a l v a l u e s . The d e p r e s s i o n i n the B.M.R. appeared most marked f o r the l / l O g r a i n dose amounting t o a 40% r e d u c t i o n from t h e i n i t i a l b a s a l v a l u e one hour a f t e r f e e d i n g the t h y r o i d . F o r the l / 5 g r a i n dose t h i s d e p r e s s i o n w a s ' l e s s marked and f o r t h e 1/2 g r a i n dose o n l y a s l i g h t r e d u c t i o n r e s u l t e d . These experiments were r e p e a t e d u s i n g l / l O g r a i n Burroughs Wellcome d e s i c c a t e d t h y r o i d , a d m i n i s t e r e d o r a l l y a f t e r an i n i t i a l d e t e r m i n a t i o n o f the b a s a l • m e t a b o l i c r a t e was made. S i x r a t e were u s e d and f a s t e d f o r 24 ho u r s . The t e s t s Yrere made, however, a t an en v i r o n m e n t a l temperature o f 28°G , somewhat h i g h e r t h a n t h a t used by Cooper. Hourly d e t e r m i n a t i o n s were made f o r f i v e hours.( c f . Table 5" graph "5 ) ""Two o t h e r groups of animals were each f a s t e d 19 hours and f e d l / l O g r a i n d e s i c c a t e d t h y r o i d a f t e r the p r e l i m i n a r y b a s a l d e t e r m i n a t i o n s had been made. H o u r l y d e t e r m i n a t i o n s were made f o r a p e r i o d o f f o u r hours w i t h one group, c o m p r i s i n g seven a n i m a l s , and f o r seven hours w i t h the second group, composed o f e i g h t r a t s . ( Table 5 graph5) 2. A d m i n i s t e r e d p r i o r t o F a s t i n g To t e s t t he e f f e c t o f a s m a l l s i n g l e dose o f d e s i c c a t e d t h y r o i d , a d m i n i s t e r e d p r i o r t o f a s t i n g , t welve animals were used. These were d i v i d e d i n t o two groups, one group r e c e i v i n g l / l O t h g r a i n Burroughs Wellcome d e s i c c a t e d 32. t h y r o i d , the second g r o u p d r e c e i v i n g l / l O t h g r a i n Parke, Dasris d e s i c c a t e d t h y r o i d . A l l animals were f a s t e d 24 hours a f t e r w h i c h the B.M.R.s were determined a t an en v i r o n m e n t a l temperature of 29° C. Immediately a f t e r these d e t e r m i n a t i o n s , t h e r a t s were s u p p l i e d w i t h normal r a t i o n s . The B.M.R.s were determined once d a i l y , f o l l o w i n g 24 hours f a s t i n g , u n t i l t h e ' b a s a l v a l u e s were found t o be normal. A comparison of the r e l a t i v e p o t e n c i e s ^ of a s i n g l e a d m i n i s t r a t i o n of these two drugs i n e l e v a t i n g the B.M.R. i s shown by t a b l e s 6 a , Cb-, graph d> . c. V i t a m i n s B l , B2,aB6 a h d a l ^ l O g r a i n t h y r o i d In d e t e r m i n i n g the e f f e c t o f a d m i n i s t e r i n g B1,B2 and B6 t o r a t s whose B.M.R.s;,had been e l e v a t e d by d a i l y doses of l / l O g r a i n d e s i c c a t e d t h y r o i d , s i x r a t s were used, f i v e males and one fe m a l e , a l l l i t t e r mates. These r a t s were f e d a p p r o x i m a t e l y 18 grams o f f o o d d a i l y and r e c e i v e d water ad l i b i t u m . A f a s t i n g p e r i o d o f 20 hours was a l l o w e d between each e x p e r i m e n t a l r u n . The animals were brought t o the e x p e r i m e n t a l rosom (temperature 28°G) a t l e a s t one hour b e f o r e a run was made and weighed each day j u s t previou-s t o the d e t e r m i n a t i o n of t h e B.M.R.s » The f o l l o w i n g t e s t s were conducted: 1. F o r seven days t h e B.M.R. f o r each r a t was determined d a i l y a f t e r a 20 hour f a s t . Then each r a t was f e d 18 grams o f f o o d t o g e t h e r w i t h l / l O g r a i n d e s i c c a t e d t h y r o i d . 33. 2. F o r the" s u c c e e d i n g n i n e days, t h e r a t s r e c e i v e d t h e same r a t i o n of f o o d w i t h l / l O g r a i n t h y r o i d and 1 mg. of c r y s t a l l i n e t h i a m i n e h y d r o c h l o r i d e . • 3. A f t e r an i n t e r v a l of f i v e days, d u r i n g xvhich time t h e rat s : r e c e i v e d normal r a t i o n s and the t h y r o i d , hut w i t h no supplement of t h i a m i n e , the t e s t s were resumed supplementing t h e d i e t w i t h t h y r o i d and 1 mg. of r i b o f l a v i n d a i l y . B a s a l m e t a b o l i c v a l u e s were again determined f o r a n i n e day p e r i o d . 4. A f t e r a n o t h e r f i v e day i n t e r v a l d u r i n g w h i c h -the normal r a t i o n and t h y r o i d a l o n e ?/as f e d , the d i e t was r supplemented w i t h 1 mg. of p y r i d o x i n e t o g e t h e r w i t h t h e t h y r o i d . The r e s u l t s a re shown i n t a b l e s 1 — IT- and graph.;,.! d. V i t a m i n s B l ? B 2 , B 6 and ^ g r a i n t h y r o i d Three,.'Ot.herogroups of r a t s , s i x t o each group, were used to determine the e f f e c t s of the v i t a m i n s B1,B2 and B6, s i n g l y and i n c o m b i n a t i o n , oh the b a s a l m e t a b o l i c r a t e , a f t e r i t had been e l e v a t e d by t h e a d m i n i s t r a t i o n o f d a i l y amounts of \ g r a i n Burroughs Wellcome d e s i c c a t e d t h y r o i d s The same e x p e r i m e n t a l c o n d i t i o n s were observed as f o r t h e l / l O g r a i n t h y r o i d , d e s c r i b e d i n the p r e c e d i n g s e c t i o n . The f o l l o w i n g t e s t s were made: 1. The e f f e c t of a s i n g l e dose o f Burroughs Wellcome \ g r a i n t h y r o i d was a s c e r t a i n e d by making m e t a b o l i c d e t e r m i n a t i o n s d a i l y f o r a p e r i o d of e i g h t days. 34. 2. The e f f e c t o f r e p e a t e d d a i l y doses of t h e k : g r a i n t h y r o i d was determined over a . p e r i o d o f seven days, t e s t s b e i n g made d a i l y . 5. The e f f e c t o f % g r a i n t h y r o i d i n combination w i t h 1 mg. of r i b o f l a v i n was now determined by making d a i l y t e s t s o f the B.M.R.s f o r a p e r i o d of e l e v e n days. T h i s t e s t was continuous w i t h the p r e c e d i n g t e s t . 4. A second group o f s i x r a t s were p r e t r e a t e d w i t h i g r a i n t h y r o i d f o r 10 days, a f t e r which they r e c e i v e d 4-g r a i n t h y r o i d supplemented w i t h 1 mg. o f t h i a m i n e hydro-c h l o r i d e f o r n i n e days. 5. A t h i r d group of s i x a n i m a l s , a f t e r being. f e d i g r a i n t h y r o i d d a i l y f o r t e n days, were g i v e n the same .. amount of t h y r o i d d a i l y supplemented w i t h 1 mg. o f p y r i d o x i n s h y d r o c h l o r i d e f o r a n i n e - d a y p e r i o d . 6. One group ofl s i x r a t s , used p r e v i o u s l y i n the i n v e s t i g a t i o n w i t h the l / l O g r a i n t h y r o i d , were now used t o t e s t t h e e f f e c t of t h e - - g r a i n t h y r o i d a g a i n s t a combination o f a l l t h r e e v i t a m i n s , B l , B2 and B6. They were p r e - f e d -J-g r a i n t h y r o i d d a i l y f o r e i g h t ' d a y s , a f t e r w h i c h t h e i r d i e t was f u r t h e r supplemented w i t h 1 mg. o f each of B l , B2 and B6 f o r n i n e days, and the b a s a l metabolism determined p e r i o d -i c a l l y . ( c f . Tables.7,^/3- /& ,graphs $-1% ) e. C o n t r o l s Ten a n i m a l s , not u sed f o r t h e t e s t s o u t l i n e d above, were used as c o n t r o l s . These c o n t r o l s were se t up as f o l l o w s : 35. 1. Four r a t s were used t o a s c e r t a i n the e f f e c t on the weight anffl t he B.M.R. of supplementing the normal r a t i o n w i t h 1 mg. o f t h i a m i n e . 2. Four r a t s were used t o determine the e f f e c t on t h e weight and the B.M.R. of supplementing the normal r a t i o n w i t h 1 mg. of r i b o f l a v i n . 3* Two r a t s were used t o determine the e f f e c t on weight and B.M.R. of supplementing t h e normal r a t i o n w i t h 1 mg. of p y r i d o x i n e . 4. Two. rat's, p r e v i o u s l y used, were used t o determine t h e e f f e c t on weight and B.M.R. o f supplementing t h e normal, r a t i o n w i t h 1 mg. of each of B l , B2, and B6. 5. Two r a t s , p r e v i o u s l y used, were g i v e n the normal r a t i o n w i t h o u t any f u r t h e r supplements' o f v i t a m i n s . These r a t s s e r v e d as c o n t r o l s t o show the e f f e c t on weight due t o th e normal r a t i o n a l o n e . The c o n t r o l a n i m a l s r e c e i v e d s i m i l a r r a t i o n s t o a l l t e s t a n i m a l s , and the. same e x p e r i m e n t a l c o n d i t i o n s were obser v e d i n making t h e m e t a b o l i c d e t e r m i n a t i o n s , ( c f . T a b l e s if a - ju , graph/3 ) . RESULTS The r e s u l t s are p r e s e n t e d as t a b l e s and graphs w h i c h f o l l o w . The w e i g h t s o f the r a t s a r e g i v e n i n grams, the temperature i n degrees c e n t i g r a d e and the b a s a l m e t a b o l i c r a t e i n c a l o r i e s per square metre o f body s u r f a c e per hour. •P © • bGceJ ctf • © . > ft) CQ -P H •H © •p Oh Ph P3 -P •rl ff) •P •H © '1*1 © © o t$ d CO t-1 -P p' m o cd IK pi, ^1 o ID * * -« » H o E-LO to to to 03 03 Ol H H to « e « ' « « 03 CO LO LO to to 03 03 03 03 o> 03 O LO 03 to to 03 03 rH r-i 03 03 03 03 03 03 CO 03 LO r-i O CD e • « « • -• o to O r-i CO to , to to to to 03 to CO o CO to o> 03 H o 0> CO to to to 03 03 03 o « to to LO * « « ov CO to to 03 03 03 03 r-i CO . LO to 05 CO O o> o> . CO CO 03 H H H H r-i OJ LO to o CO a « « 1 * to o LO to to to to to OJ 03 03 CO t-to O CO Or Oi a» CO co r-i H H r-I r-i r-i o> H to o H O 03 to OJ to to to 03 H CO r-I 03 O to •a -P to as fl •ri PQ EH I ,Q H CD a) EH CO CD -P to ID 1-1 * ;P en-'s-CD CD H OM LO O 03 ft 'OH S> PQ 'PQ, PQ • PQ H 03 • b—< '+& • . PQ *0 to • O 03 ft -P • PQ to 03 03 • • •p PQ 9 P-s EH o tc| !h -P p" 03 o cd tOO3C0HJ>Cr>C0a>C0 » • • •>*>«'*'• « OOOriHHriroffl t003tOtOtOtOtOC303 tOO03£>0>tOC0CQiH *» » * ft « ftftft « ©rood OH 03 o> o 03 03tOtOtOtOt003tO lO tO ^ CD CD CO H O CO » • ft ^ 03 tO 03 • CD tO • (M' O to to to to to to to to to CT>tOO3HC0tOtOC3tO a o.k 6 e • • » • cOLO£~C0I>C0CDlOCO O3O303O2O3O3O3O3O3 tOH^O)(DHOCOtO • • • * ' * r -4 • • » OlOHOMCOlOHO) wtototototototow Z> 03 H CO tO 03 tO to • »*• « CO CT> O O C5> 0> O OVCO 03O3tOtOO3'O3t00303 03tOc000 03 0!>tO i « ft ft ft < ft ft « « « tO CO H 03 to LO H a> toojtotototototooj OjLOtOHH^tO^tO O C5> H 03 tO rH 03 0> £-tO 03 tO tO tO tO tO 03 03 cocococ^!>t~co;>co O3O3O3O3O3 03 03 03 O3 GDOHOJtO^LOCDC-H0303030303030303 37. o 0 C5 o c LO • i-f to Oil P •a •r-i © CQ -P ..faC •H © K m » co •p •H © CQ •ri © p to to to CO LO o to LO o to • 03 03 02 OJ 03 . r-i 03 to 05 CO co • * « » O CO to o r-i to LO LO to to LO LO r-i to o to 05 o to LO H to 03 03 03 03 03 H 03 r-i to to r-i ;C0 * • • • CO CO LO 05 L> co to to to to to to o CO o o r-i r-i J> 03 03 03 03 03 H 03 H O 03 LO 03 CO O » « » o CO LO O CO 05 t-to to to to to to CO r-i r-i to o o LO c-03 £-OJ 03 03 03 H 03 LO O to 03 03 to to H « s • • 1 « 05 o to O to to to © o t* c<5 $ faO OJ Of-: *o © tt -p ccS tt fcc! © IBs into -p as tt 0*£ -P K <D re ta a, bD| H tt <s otfxl, bC] © -P tt © LO o> 03 rH H CO • ft ' ft • ft 1 ft " ft ft r-i co £-LO to . CO to CO to CO CO tO to o rH 03 ft ft ft ft 0 ft •• « CO 03 CO co fc-co to CO to to LO LO to a> CD LO 03 co 9 -03 CO CD co £> rH rH H ;  tH rH rH 03 03 CO to LO £-ft ' ft ft 1 ft ft -ft 1 * ft CO o CD to o CO LO LO LO co to 03 LO 03 to 03 03 CO CO rH CD rH 03 CO H H rH 03 03 03 to to LO, ujr: to 03 o ft -« ft  1 « • ft  1 ft  1 » o CD 03 to LO CD 03 LO ^ .'• to to CO to rH CO to to CD £-CO CO o H CD O rH rH rH rH rH 03 to to CD to CO to CO ft . « • • ft -• tt ft ' ft 1* ft OS o CO LO to CO to to 03 LO CO"* LO c~ to CO CO co 03-to co -.-o rH •H H rH 03 CO 03 o> 03 CD I> CO 03 03 03 CO 03 co 03 CO O rH rH rH 03 co 03 CO 03 40 Table 4 V a r i a t i o n I n th e B.M.R. due t o the D i u r n a l F a c t o r Rat Q_ 5- CT 5 (f c, Q ^ G Time B;.M.R. B.M.R. B.M.R. B.M.R. Ay^B.M.R. 10 A.M. 31.22 36.14 35.32 32.58 34.08 12 A.M. 31.84 35.18 35.18 33.56 33.56 4 P.M. 31.21 36.12 36.50 34.98 34.98 ^ tO r-J tO tO o t> c- co .03 j> * tO 03 03 tO 03 tO 03 <NF to to LO »'••>•» « « MOCOO to t-* 03 to to 03 JO 03 to 0 CO tob £- ^ ^ LO to • » I • »' • • • » t- to 05 O r-l 03 to COO3f*tOt0tOt0 03 35 to tO ^O to to to OJO^WO • • • ' • ft * O O iH J> O 03 LO O H t~ %••*»•* LO t- b- t- G> LOtO ^ -sH -sM to tO tO tO H to 03 H 03 O • • e » • • * tO rH tO t- J> tO 03 ,^ ^ to to to to J> 03 ^ tO 03 H tO • • • « * * • O £> O tO' LO 03 CO to <tf ^ to to C3 LOO3O3C0O3tO'^J> * ft « A ft H O) H lO O 03O sHtOtOtOtOtOtOC3 -JtOLOLOrHOir-ltO ft «'«'«'« % ft « MCOOtDtOCOtOH tO tO tO tO 03 tO tO ^ OMO O rH ^ LO « « e • • % • • CJ5 C- J>LO"^030 totocotototototo 3> tO CO ^ J> tO tO • » • • to !> to tO tO O 03 CO tO to tO tO tO tO 03 03 p tO LO to to to to © Q5 03 LO O W ^ 03 tO to tO ^tOMOOOIHW * • » •.• • • • « LO LO <^C0 03 to O J> tO to tO 03 CO 03 to 03 tO CO LO to O LO LO iOt~ CO to LO t- ^ • • • * • • • « • • » • • • • • , tO 05 05 CO 03 i—1 05 CD LO LQ © rH J>- © 05 i <tf to tO to to to 03fO to tO to tO 03 tO 03 f ~- ^ -to tt v <i! ^'b'b'b Of Ot- C+ B'b,Wo4- OfOfCM-'b1^ Ofof'Wl O L -E. 0° £ 0 1, — „— V-"XT 00 0 0 c -z- -° 00 0 0 c "g 0 T> S. •X> < c e> a L _^ T> S. •X> < c e> a CJ CD ifi o -J —j \0 —^ ,„ -V->, T y> • / y> O / 0 0 t. r-r-a: i / 0 0 $ r-r-a: i / 1 r-r-a: i / / cS O UJ o / 2 O l --cc --o >" -T" o >" -T" < h s < h s 0 f XT 0 UJ tO L_ j 1 < 1 in f in •C3 O O <1 2 1 CD / a. O ~Z u. ID CD / O ~Z u. .8 u. LU \ 1 \ \ 1 \ \ \ \ \ \ \ \ \ \ \ 2 8 *! ^ 0 0 0 8 *! ^ g O 0 0 0 0 .-8 *! ^ ^ • 0 .-•iii — J *> > y y o 0 CO 03 CO t- CO o 0"> CD CO CO LO O) rH 03 03 03 03 rH tO CD. LO 03 t- CO ft * ft ' ft ft ft O H ^ W to to to tO CO CD LO CO CO OS CO o> CD co LO "vf o> rH 03 03 03 03 rH 03 LO, to -vfi 03 LO tO ^ 03 CD J> co ^ to to tO CO to CO to O D- LO 0> t- CO LO CO GfJ rH 03 03 03 03 H r-i Oi CO to LO • • • • • 03 O CO r-i CO ^ ^ to to to to to CO CO J> to CJ) o 0> t- CO CD LO O H 03 03 03 03 03 ^ 03 t> rH £-• ft • ft • « « • e a CO 03' COCR tO r-i tO tO CO 03 CO tO a <D EH %|CO>cr S. CD © o o © 03 W A CO. 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EH LO CO s. •ri © CQ -P TH © o CO cd Q 03 CD CO ^ tO CO CO LO LO rH r-i 03 03 OS OJ 03 co co t- co 05 to © CO CO O O ^ LO co co ^ •* t~ LO ^ tO CD CO CO t- CO LO rH rH 03 03 03 OJ 03 03 rH 03 03 03 • • « 05 ^ f- rH f- CO • CO CO ^ CO CO CO rH 03 05 H 05 t- £- CO LO H r-i 03 03 03 03 03 LO <Ji CD' J> CD LQ * « e © • « 05 LO CO CO CO CD CO EX} CO CO CO ^ LO CO 05 to CO ^ 05 t- CD £- j> 03 r-i OJ 03 03 OJ 03 too t- CO CO i> O 'ID LO OJ co co co co co."* H rH CO tO CO ^ 05 CO C~ J> t> OJ rH 03 OJ 03 03 03 05 CO CO OJ O) OJ r-i OJ CO LO CO CD CO CO CO CO CO CO otb'bo'bo*--p CO <H © U O © fit rH •H cd nd cd •H. O u +3 co © cd ; bO o H o ra © CO o %J © •P cd © ft © « I .CD © H cd EH co LO to 03 O o o CO 03 ft ra, s N © cd E-) Q CCJ :PQ * PQ ft 4? •. «s «• PQ PQ PQ PQ PQ co •p cd CO CD tO rH J> ^ CO E- "tf< LO CO CO 03 03 OS OS 03 rH ^ -^f O rH CO CO ft • ft - ft • ft 9 CO 03 CO CD CO t— to ^ ^ ^ LO rH CD CO CD CO CO LO LO CO CO OS 03 OS 03 03 rH C- CD -NH CO CO CO e -»-«»' » « t- CD LO LO lO CO i to to ^ ^ ^ rH 03 CD CO t- LO CD CD LO LO CO c-03 03 03 03 03 rH CO CO C~ to CO 03 •' * ' » ft i ft •, « CO O CD LO CO tO ^ -vf ^ CD CO CO CO 03 J> CD CO LO CO CD J> 03 03.03 03 03 rH 03 co to r> to r> • e . ft > ft " • 1 tt tt CD O ^ 03 CD to «^ <tf <tf 03 rH O O LO CD O CD CO t> CD £> tO 03 OS 03 03 H GD 03 tO r-i CD CO OD o> r> j> o co to to ^ ^ T^i 03 O 03 E> CD rH CD CO J>- CD C-tO 03 03 03 03 H CD CO rH rH CD tO co r> c- to co to to to *p••sB to CO rH o CO ei O CD CD J> CD CO tO 03 03 03 03 H CO CD CD J> O ^ • ' • 1 « 1 ft ' ft . • 03 CD CO E- CD CO to tO ^ to CO rH E- LO CO rH O r—I O CO CO CD CD CO CO 03 03 03 H LO £- O CO rH CO ' ft ft ft H CO CO £> rH to to to tO *~ <~ tr S i ' ^ ^o'oo'oW | 03 LO 03 CD LO LO 03 CO © ft to - -P © bO O o -P CO 03 <d •H rH o ft rH (» -P to sd CD iH • © 03 cd rd in •H to flO U ft o CO o rH •sH rH \ H o CD rH CD ^d 03 O CO co © © CO CO o •H & cd CD i» •H CO rH 43 03 •H cd CO ft 0 o TJ-> S ©«*-•P rH cd © CD ft •P CD © 03 ptd . •' ••• '; « CD o to •rH ©' rH 03 & E-cd 03 EH -lO « to © bCi cd in © > CO CD LO to 03 O CO cd m +3 PQ I PQ 04 .a PQ K PQ •f=5 PQ PQ PQ CO •p cd rH H tO tO 03 CDAA LO CC? CO LO CD t- t-f^lo <M 03 03 03 OS rH I CO to OS tO H 03 t> %  • * • • • • H <0 CO O CD CO CO CO ^ CO CD rH O rH CO CD [> CO LO CD £> t~. 03 03 03 03 OS rH LO Ob CO tO t~ t  ft ft ft * ft Oj t- !> 03 CO to CO ^ CO ^ CD O CO O H LO J>- CO CD J> £~ 03 03 03 03 03 H 03 CO 03 O CO 9  « ft ' ft ' ft » [O ^ CO H 03 CO ^ to to tO ^ rH 03 CO CO OJ ^ CO CO LO tS !> 03 03 03 03 03 rH CO rH O rH 03 rH LO CO CO CO CD CD ^ CO to CO CO 03 tO CO ^ £> rH £> c- to LO. co r> 03 03 03 03 03 rH LO LO LO 'vH c- l> rft ft ft ft ft ft to ^ O LO CO rH ^ CO ^J* tO ^ CO LO CO CO t- CD t> ^ ^ CD CD 03 03 03 03 03 H H rH CO r-i rH rH CD CD CD to HI CD LO ^ to ^ Ht~.CD CO t-03 03 03 tO CO CO LO CD CD 03 03 <H rH CO rH LO rH to O •sH "5f ^ ^ CO LO ^ CO ^ 00 t> -<0 r-i CO CD CO S> ^ LO CO CO 03 OS 03 03 03 rH CO tO I> rH. 03 » ft • ft ft ft OJ H CO 03 LO ^5 LO ^ ^ ^ CO CD tO rH D-CO !> ^ LO CD CD 03 03 03 03 03 H ^ ^ O H CO CO ft « ft ft ft ft CO 03 CO CD CO C~ to ^ ,TH. $1 d CD CO LO 03 LO « o 03 LO 03 Table 11 - Repeated D a i l y Doses o f l / l O g r a i n D e s i c c a t e d T h y r o i d t o g e t h e r w i t h 1 mg. of R i b o f l a v i n Temp. 28C'C Days 0 5 7 9 10 Rat .BMR Wt.' BMR ,Wt. ; BMR Wt. Wt* BMR Wt. (pi 39.4 275 35.6 279 32.2 282 287 31.8 288 Cft t 34.0 279 32.8 276 34.0 279 286 32.4 290 0*1 41.5 250 38.1 242 39.5 250 269 38.1 268 ©p ' l j - 49.2 182 47.8 179 46.3 183 199 41.1 197 0* "> 36.9 262 30.2 266 28.7 270 282 27.8 283 0^ r/: 59.4 275 39.1 267 58.1 268 277 57.2 276 Av. 40.7 254 37.3 252 36.5 255 267 34.7 267 Table 12 - Repeated D a i l y Doses o f l / l O g r a i n D e s i c c a t e d T h y r o i d t o g e t h e r w i t h 1 mg. o f P y r i d o x i n s H y d r o c h l o r i d e Temp. 28 °G Days 0 3 6 7 10 Rat ..' BMR Wfc.. .. BMR wt. : wt. •' BMR Wt. BMR Wt. 0^7 37.2 280 35 • *7 283 •'. 279 31/4 272 33.1 270 CP7 1 36.7 265 36.9 279 280 37.6 273 39.2 273 38.0 248 39.2 245 249 40 ;.5 248 38.3 257 Q, 52.8 172 45.9 186 189 46.4 179 43.0 188 io 37.7 260 34.9 281 278 36.1 271 35.4" 270 <¥> il 38.5 257 34.6 272 275 35.7 262 34.2 266 Av. 40.1 247 37.9 258 258 37.8 251 37.2 254 46. T a b l e 15 - Repeated D a l l y Doses o f |- g r a i n ., , D e s i c c a t e d T h y r o i d t o g e t h e r w i t h 1 mg. of P y r i d o x i n e H y d r o c h l o r i d e Temp. 28°C . Days; 0 - • ' •. -4 \ 9 Rat,;,, B.M.R:. /Weight B.M.R. Weight B.M.R. Weight Cf7.'* 33.1 234 32.4 239 34.7 238 <f"+ 38.1 247 43.9 245 44.8 246 CT if 32.3 394 34.5 393 .33.0 387 Q. <b 48.8, 214. 45.3 213 44.5 218 (y 'i 37.9 229 36.4 231 32.3 230 (y.'-i 34.8 260 33.2 261 34.0 259 Average 57.5 265 . 57.6 264 37.2 263 Tabl e 14 - Repeated D a i l y Doses of \ g r a i n D e s i c c a t e d T h y r o i d t o g e t h e r w i t h 1 mg. of Thiamine H y d r o c h l o r i d e Temp. 28°C Days . 0 4 9 Rat ;B.M.R„.: Weight B.'M.R. Weight B.M.R. Weight <y "? ' 36.1 306 39.5 298 39.6 292 37.4 258 .35.9 260 '. -37.4 258 58.4 386 38.9 391 : 40.7 389 40.9 231 39.0 226 38.3 225 42.7 204 '; 42.0: 207 40.8 206 45.3 194 ,43.9 195 44.0 * 196 Average 40.1 263 39.5 .266 4-0.1 261 ____ > : v s, V \ \ i s L V) X. -0 V) X. -0 1* } V) X. -0 •o* l! N —U \ f s c X 0 > s c X 0 > s c X 0 > < *. —_ *. —_ c L_ ! J*. o -0 ST J*. -0 > i -J J" > i <S f-<S f-<S <S hs > i— y y y — v r s i « > > s «§ ft "} Tj r i-ft. U i I o 5). c c • • \ • ? t < *> *> *> 47. © -p cd O o •H co © cd. ft bO H|* : «t-li O co © co o Q (3 •H > cd rH CH O £> •H K o bO 43 -P •H ft © i»43 H -P •H cd <D bO o •P 'rrj © TJ cd O © ft ©,43 K EH I LO rH © H 42 cd EH O rH CO LO 03 O O o CO 03 P. CO S ^ © cd EH Pi •P 43 •rH © I .CQ -P 43, bO] •H © tt PQ -p 43, •H © •P b0| •H - © tt CQ -P ^, bCj •rl © •P •H © CQ +3 cd tt LO CO CO o LO CD CD CO CO LO CD 03 rH 03 .03 03 03 OV 03 to o CD CO 03 rH CD ' tt ' ft • tt ' ' ft ' » tt ft o LO rH to LO to to to to to to to to H to CO 03 to CD CD co CO LO LO 03 rH 03 03 03 03 03 03 CD LO 03 to CO 03 CD « ft ft ft , ft « 03 CO LO 03 CO .': CO to to to to to to CO CD LO to o CD CD E-CD LO LO H H 03 03 03 03 03 03 CD CO 03 H 03 co « . ft | ft * ft ft ft to !> to LO E-E-to to to to to to o E~. CD CD to CD CO CO LO LO rH rH 03 03 03 03 03 03 03 CD CO rH H CO .LO CO CD E-O CD CD CD to to to to to 03 CD LO fc- 03 CD 03 CD CD CD LO LO H H 03 03 03 03 03 03 03 CD CO ^ to CD CO CD LO LO H to H 03 03 03 03 OS 03 CO O to O O LO' to • ' ft • ft ft ' c ft. ft o CD CO CD CD rH rH LO to to to to OrO o o o oV ft > < CD CQ »H TJ O d ft cd & 43 03 EH PQ TJrH <D PQ -p cd o o co cd © +5 Q£ 43 •H cd ft bO 43 o cd © O 00 © co o O CM O CM O bO H 43 H-P cd «H O'.jss. TJ ft © © -P 43 cd -p © © P, bO © o tt -P CO rH © rH 43 cd EH CD LO o o tt 0 CO PQ 03 ':-ft a, co g t>= -P © cd cd EH « tt -p 43, •H © tt PQ •P ^, bO] •H © K CQ •P "tin •H © ^ CD CD LO O I> LO lO to 03 03 03 03 03 03 LO CD LO LO O 0 ft ft ft ' ft * 03 rH H fc- <tf t-tO tO tO 03 tO tO OOW^ri.H O E- LO -^W to 03 03 03 03 03 03 E- 03 CO tO LO « * » » « » CO tO LO O CO CD to to to to to to O O CO H tO E-CD LO ^ CO CO rH H 03 03 03 03 03 CD CD ^ 03 E- >vH « « » « • • co co ^ ^ co to to to to to CO ^ > f< t* V> J o^o o o cb ov! LO 03 LO » -03 to O 03 CO ft LO CO E~ 03 03 O ft CO © ; b0 cd ft © . „ — : : . 1 i 4—• • -V, 1.9, -JM \ * Cq. li ...1. io E \ to ^ V, 1.9, -JM \ * Cq. li ...1. io E \ to ^ s E £ is e a s-a « . .. i s E £ is e a 00 >J •a \ 6 \ £ \ / ,..-/J_ : 1 ™ ^ / H* \ i \ 9 \ Ho / ;'T :r  i ! ;-! • /' \- j-. 1. :.. . ..sKJ •. i ; - i • >-J • r- • • 1—: !-••!- - •' ' -• -[-!• •!--'-" -t-r - -f-h \ O / \ 08 / \ ^ / \ / r> « > -^ (*• /v Q f> o o S| S i 5 iLrn.txn.j-. I j 1 i! j i •! )•-» i l-l-i-f! i (-••-HrH S3 • ' • '•—i: m\ '• H 1 |T| j 1 [ > < H 11 1 1 • 1 ; '|||;;: ' " \ i s / Cj 0 / 1, / CM / \ v \ 1 f • / \ Q \ > c •J ,< 3 ••1 I / c 0 1 1 sT r ii c t 1 I N 4 4 V * •s • J <r , I \ 4 i* >H si s <J V <J j oo V N I* ft I T T 5 V < N to > 1— 1 »^ f» 5* r \ —q f ... •? •? V 1 1 CJ x > s. > s. 0 f i f Ml 1 Ml j < *--i u < *--$ > < > c \ c Q $ \ \ f c< <N i << c< f r t !) t !) fj ... ' 1.1. 1 s L •5 < J 5 i c j c j c <: 3 • > .3 ft 1 « 7 \ i Y u. i n V ) S>s. c c ^ "ft R 1 In |_J L .]„ .{s J V 5 5 • y ft u s c o-w o-(. j u J u u. u. 1 1 1. -( *s J * \ \ \ \ \ \ \ • y \ \ < 0 c ) 0 0 o A c~ c-( $° tt tt 48. m p-o P3 EH o o A •H cd rH o •H o A •p •H •S © -P Pi © © rH ft ft £ •P © •H P cd a Pi O cd rH © H 43 cd EH CD rH 03 H GO O o co 03 ft CO a N © cd EH P -P b0| >H © P4 CQ •P bO| •H © PQ b0| •H ©. S3 PQ tt .'CD PH •S PQ •P 43 •H © m PQ -P' cd PH £- CD rH ^ 03 03J03 ^ 03 O CO to to rH 03 03 03 CD tt ft rib tO to £- o o to 03 03 03 <tf - .ft - •ft' LO 05 to to rH rH '© to 03 03 03 tO • « ft •sH O tO £- H CO <H H 03 03 to CO to to it— c* 03 rH 0> D^lCO LO o CO cd P to CT> CO wo rH 03 03 03 H CD co ft 03 O CO to ^ CO H o K\3 03 to CO 'ft ft LO rH CO CO CO [LO.05 05 03 rH &01O3 H © 03 CO P 03 VXt rH h# C3 .. o ;co cd Pi © IOr04<. © Pi a cd •H 43 EH o bO-a 43 -p •H : iS © • 53. © a © rH ft ft 00 © •H P rH Cd a Pi O is; 43 L> H © rH 42 cd EH to rH 03 rH 05 LO 03 O 0 CO 03 o -p 43 •H © PQ s b[ © CQ. += 43, bOl *H © PQ - >H © PQ -P •H © PQ 1| •H © Pr4 a PQ ft ft m +3 © cd cd EH.P K CO rH 05 05 o 03 rH 03 H 05 02 o • ft CO LO CO to to to CD CO 03 05 03 <H rH H CO 03 O • tt ft LO CO CO to CO co o 33 05 o 35 rH 03 H rH to • ft ft to to to CO CO LO t-CO 05 05 35 H rH rH 03 H L>. ft - ft . ft LO CD LO to to. co 03 CO O co 03 02 rH rH H LO 03 1 « ft • ft to LO to to to 05 05 05 CO CO CO rH rH —i CD «; - * ft co-LO co to co o •> oVo* CO J> CO CO 03 03 03 05 CO to to CO 05 CO 03 03 LO CD I ft ft P CO ,t0 to 03 <tf 03 03 CO 03 03 [CO CO 05 jtO 03 OO H LO 03 5f CO rH 03 03 CO LO CO 03 03 to 03 CD O to > Table 17c - Normal D i e t Supplemented w i t h . 1 mg. P y r i d o x i n e Temp. 28°C Days: 0 3 9 12 'Rat BMR' Weight BMR .;Weight BMR Weight BMR Weight Q. '7 34.3 174 40.1 196 36.2 186 38.7 204 35.2 179 37.3 202 37.3 180 42.7 204 Av. 3Y .'d 13b 37*5 195 "36.3" 191 40.0" 1915— Ta b l e 17d - Normal D i e t Supplemented w i t h 1 mg. o f each o f V i t a m i n s B1,B2 and B6 Temp. 28«G fays.:: 0 1 6 11 Rat BMR Weight Weight BMR •Weight' BMR Weieht 0 3 o r- %q 37.3 204 34.2 180 206 40.3 215 39.0 224 185 38.2 199 35.3 215 AV*,/ : 35.7 X92 195 39.3' 207 37.2—320 T a b l e 17e - N o r m a l D i e t w i t h o u t V i t a m i n Supplements Days 0 5 6 9 10 R a t W e i g h t Weight Weight Weight Weight 0. •\i 169 178 182 184 181 g. 196 " 210 214 213 209 Av. 182 OTP""" 198 " , 1 T 4 - 190" 50. DISCUSSION • / Animals A l l animals used were the o f f s p r i n g of f o u r b r e e d i n g animals o b t a i n e d from t h e W i s t a r I n s t i t u t e , P h i l a -d e l p h i a , i n September, 1942. No r a t s used were under f o u r months of age, the major p a r t o f the work b e i n g done when t h e y were from seven t o t e n months of age. The r a t s appeared t o be i n normal h e a l t h , a l t h o u g h a few developed a c o n d i t i o n symptomatic o f v i t a m i n B2 d e f i c i e n c y . Evidence of t h e c o n d i t i o n appeared as l o s s of h a i r , r e d d e n i n g and f o r m a t i o n o f a s c a r around the eye. Not more than one eye was a f f e c t e d and i t was observed t h a t the c o n d i t i o n d i d not reappear a f t e r the a d m i n i s t r a t i o n o f r i b o f l a v i n . B2 c l e a r e d up t h i s c o n d i t i o n i n two of the animals so a f f e c t e d . Though some o f th e t e s t animals were f e d t h y r o i d c o n t i n u o u s l y f o r a p e r i o d of almost seven weeks, a l l animals s u r v i v e d , a l t h o u g h some workers ( f\<) have r e p o r t e d a f a i r l y h i g h i n c i d e n c e o f mort-a l i t y among r a t s as a r e s u l t of t h y r o i d t o x i c i t y i n d u ced by t h y r o i d f e e d i n g . That t h i s was not found t o o c c u r , may be a t t r i b u t e d t o t h e f a c t t h a t t h e r e I n t e r v a l s of v i t a m i n f e e d i n g , w h i c h , i t i s b e l i e v e d , tended t o o f f s e t the t o x i c i t y r e s u l t i n g f rom the i n d u c e d h y p e r t h y r o i d c o n d i t i o n . Apparatus The e x p e r i m e n t a l c o n d i t i o n s under which the t e s t s 51. were made were as u n i f o r m as p o s s i b l e . I t might be empha-s i z e d here t h a t a c o n s i d e r a b l e source of e r r o r w i l l a r i s e u n l e s s c a r e i s t a k e n t o r e p l e n i s h t h e soda l i m e used t o absorb t h e carbon d i o x i d e and m o i s t u r e from the animal chamber. T h i s i g r r o r can e a s i l y l e a d t o a m i s i n t e r p r e t a t i o n of r e s u l t s , s i n c e f a i l u r e t o absorb the carbarn d i o x i d e w i l l g r e a t l y r e t a r d r e s p i r a t i o n i n t h e animal chamber. As ment-i o n e d p r e v i o u s l y , i t i s recommended t h a t t h e soda lime be renewed a f t e r not more th a n 48 twenty minute r u n s , or , i f the apparatus i s i n f r e q u e n t l y used, at l e a s t once each week. A f t e r u s i n g , the soda l i m e s h o u l d be p l a c e d i n the d r y i n g oven. The k i n d and q u a l i t y o f soda l i m e s hould be the: same> throughout the i n v e s t i g a t i o n . F a c t o r s A f f e c t i n g t h e B a s a l M e t a b o l i c Rate a. P a s t i n g As t h e v a l u e s i n T a b l e l a show, the m e t a b o l i c r a t e showed a marked drop from c e s s a t i o n of f e e d i n g t o t h e 18t h hour p o s t - a b s o r p t i o n . A s t i l l l o w e r v a l u e f o r the B.M.R. was-obtained a f t e r 30 hours f a s t i n g . At the 2 4 t h h o u r , however, a v a l u e s l i g h t l y above t h a t a t 18 hours was found. The r e s u l t s a r e t h e r e f o r e i n agreement w i t h th e f i n d i n g s o f Kingdon,Bunnel and G r i f f i t h (3<>) a l t h o u g h t h e r i s e i n . t h e BMR from t h e 1 8 t h t o t h e 2 4 t h hour wasenot a s pronounced. T a b l e l b shows th e r e s u l t s o f t h e subsequent t e s t t o determine t h e f a s t i n g metabolism o f t h e r a t from t h e 1 9 t h t o the 2 7 t h hour , making h o u r l y d e t e r m i n a t i o n s the B.M.R. and u s i n g seven r a t s . T h i s t e s t confirmed the p r e v i o u s one, a s l i g h t l y h i g h e r v a l u e "being found a t the 24-th hour of f a s t i n g . Kingdon,Bunnel and G r i f f i t h l o o k on the low metabolism observed a f t e r 18 hours f a s t i n g as b e i n g midway between the metabolism o f mixed f o o d s t u f f s and one e x c l u s i v e l y of f a t , by which they attempt t o account f o r the h i g h e r m e t a b o l i c r a t e a f t e r 24 hours f a s t i n g . T h i e x p l a n a t i o n has support i n t h e work of B e n e d i c t ( 3 ), who s t a t e d t h a t the r e s p i r a t o r y q u o t i e n t of the r a t , f a s t e d 24 h o u r s , i s .72 , whic h i s the R.Q.. when f a t alone i s m e t a b o l i z e d by t h e body. These r e s u l t s are o f i n t e r e s t s i n c e they h e l p t o c l a r i f y t h e a p p a r e n t l y c o n t r a d i c t o r y r e s u l t s o b t a i n e d when t h e d e s i c c a t e d t h y r o i d was administ-ered t o the f a s t i n g r a t . ( c f . Table 5,graph 5 ). I t i s concluded from t h i s t e s t , t h a t s i n c e the B.M.R. does n ot appear c o n s i s t e n t a f t e r 18 hours f a s t i n g , i n making a s e r i e s o f d a i l y d e t e r m i n a t i o n s o f the B.M.R., t h a t t h e same i n t e r v a l o f f a s t i n g be a l l o w e d between each d e t e r m i n a t i o n . b. E n v i r o n m e n t a l Temperature The average B.M.R.s o f ; t h e s i x r a t s used appear i n T a b l e 2, page 38, as follows-. Temperature 21°C 27°C 3±.5°C 39°C .Average,B.M.R., 40.15 37.01 37.71 58.3 53. The Values show a d e f i n i t e drop i n t h e B.M.R. at 27"C as compared t o 21"C, i n d i c a t i n g t h a t at 21°C the metabolism i s not b a s a l , what p r o b a b l y c o n t r i b u t e d t o the h i g h e r v a l u e at 21°0 i s t h a f a c t t h a t a t t h i s temperature i t was d i f f i c u l t t o c o n t r o l t h e a c t i v i t y o f the a n i m a l . At 27°C, w h i c h i s somwwhat h i g h e r t h a n t h a t of the r a t ' s normal environment (25.5^0), a c t i v i t y i s p r a c t i c a l l y n i l . As many w r i t e r d have p o i n t e d out, b a s a l metabolism does n o t e x i s t when t h e r e i s a c t i v i t y p r e s e n t . The h i g h e r metabolism at 21 C i s i n p a r t a t t r i b u t a b l e t o the g r e a t e r t i s s u e metabolism which o c c u r s t o h e l p m a i n t a i n the body temperature i n t h i s lower e n v i r o n m e n t a l temperature. B e n e d i c t and MacLeod ( j f ) r e p o r t e d t h a t 28°C was the temperature o f t h e r m a l n e u t r a l i t y f o r the a l b i n o r a t . S w i f t and Forbes set a s l i g h t l y h i g h e r temperature o f 30"G as t h i s " c r i t i c a l temperature". The r e s u l t s o b t a i n e d i n d i c a t e t h a t the B.M.R. i s o n l y s l i g h t l y a f f e c t e d by an i n c r e a s e i n temperature from 27°C to 31°C. At a temperature o f 39°G, t h e metabolism showed a c o n s i d e r a b l e i n c r e a s e ( 57.5% over t h a t a t 21°C). The i n f e r e n c e from t h i s h i g h v a l u e i s t h a t above a c e r t a i n t e m p e r a t u r e , i n t e r m e d i a t e between 31.5°C and 39"C, e x t e r n a l heat has a thermogenic e f f e c t on metabolism. The animals appeared t o s u f f e r from the h i g h temperature, became i n e r t , and showed a d i m i n i s h e d f o o d i n t a k e f o r a few days. I t may t h e r e f o r e be i n f e r r e d from the above r e s u l t s , however meagre t h e y are> t h a t t h e r e i s a maximal temperature below which . ... - , 54. the heat p r o d u c t i o n v a r i e s i n v e r s e l y as the temperature, and a m i n i m a l temperature abarve which t h e r e i s a thermogenic e f f e c t , a c c e l e r a t i n g metabolism u n t i l death r e s u l t s . .The e x p e r i m e n t a l c o n d i t i o n s f o r c o n d u c t i n g t h i s experiment were i d e a l . The animals were p l a c e d i n the experiment room f o r upwards of one hour b e f o r e the runs were made and were thus a d j u s t e d m e t a b o l i c a l l y t o the en v i r o n m e n t a l temperature. The room temperature was the same as t h a t of the animal chamber d u r i n g the r u n . c Age The r e s u l t s o f the i n v e s t i g a t i o n t o determine the v a r i a t i o n i n t h e B.M-.R. as i n f l u e n c e d by age are shown i n T a b l e 3, page 39. The average v a l u e s show a f a i r l y s teady drop i n t h e b a s a l v a l u e s w i t h i n a sh o r t space of time. I t i s to be r e g r e t t e d t h a t - time d i d n o t permit c o n t i n u a t i o n of t h i s p o r t i o n o f the i n v e s t i g a t i o n , beyond t h e 12th week. The r e s u l t s show a sharp drop i n the-B.M.R. from the 6 t h t o t h e 9 t h week, a f t e r which the v a l u e s appeared f a i r l y c o n s i s t e n t t o t h e 1 2 t h week. Weekly d e t e r m i n a t i o n s were not c a r r i e d on a f t e r t h e 12th week, b^ct v a l u e s o b t a i n e d at 28 weeks o f age show t h a t the drop from the 12th week i s not c o n s i d e r a b l e . A comparison o f t h e B.M.R.s to t h e growth g a i n s i n d i c a t e s t h a t the g r e a t e s t a c c e l e r a t i o n i n growth o c c u r r e d d u r i n g t h e few weeks when t h e metabolism was h i g h . . d. Time of Day The r e s u l t s from Table 4,page 40, show a v e r y s l i g h t v a r i a t i o n i n the B.M.R. measured at 10 A.M.,at 12 A.M. and at 5 P.M. Prom 10 A.M. t o noon t h e r e i s a r e d u c t i o n o f l.dfo i n t h e average B.M.R. s, and at 3 P.M. t h e r e i s a r i s e of 4.1$ over midday. T h i s v a r i a t i o n i s s l i g h t as compared w i t h t h e v a r i a t i o n . d u e t o o t h e r f a c t o r s such as temperature and. f a s t i n g . ' W h i l e the d i u r n a l v a r i a t i o n may be pronounced when o t h e r v a r i a b l e s o r d i n a r i l y encountered, such as te m p e r a t u r e , f e e d i n g t i m e s , and a c t i v i t y have t o be c o n s i d e r e d y e t where an attempt i s made t o mi n i m i z e these v a r i a b l e s by e x p e r i m e n t a l and l a b o r a t o r y c o n d i t i o n s , the d i u r n a l v a r i a t i o n can be expected t o be s m a l l . F u r t h e r , s i n c e the e n v i r o n m e n t a l c o n d i t i o n s o f t h e c o l o n y r a t s are u n i f o r m throughout the y e a r , i t followed t h a t s e a s o n a l v a r i a t i o n s can l i k e w i s e be e l i m i n a t e d from m e t a b o l i c d e t e r m i n a t i o n s . -D e s i c c a t e d T h y r o i d a.. A d m i n i s t e r e d a f t e r F a s t i n g The v a l u e s of t h e "B.M.R.S a f t e r t h y r o i d a d m i n i s t -r a t i o n s to. t h e f a s t i n g anima^L'eaflSB shown i n Table 5,page 41. From t h e 18 t h t o t h e 2 4 t h hour p o s t - a b s o r p t i o n , the B.M.R.s show a r i s e ( c f . graph 5 ) . That t h i s e l e v a t i o n i n the B.M.R. can.not be regarde d as t h y r o i d s t i m u l a t i o n of t h e metabolism i s demonstrated by the B.M.R. v a l a e s o b t a i n e d from the 24 t h t o the 27 t h hour of f a s t i n g . Comparing t h e curves o b t a i n e d i n graph 5, w i t h graph 1, showing the.heat p r o d u c t i o n o f the f a s t i n g a n i m a l , i t a t once becomes apparent t h a t the 56. a d m i n i s t r a t i o n o f l / l O g r a i n d e s i c c a t e d t h y r o i d t o the f a s t i n g a n i m a l has p r a c t i c a l l y no immediate e f f e c t . Thus the r e s u l t s o b t a i n e d b y Cooper f o r the l / l O g r a i n dose a d m i n i s t e r e d 24 hours p o s t - a b s o r p t i o n may be e x p l a i n e d on t h i s b a s i s . The l e v e l l i n g of the cu r v e f o r the l / 5 t h and|r ,grain doses of t h y r o i d a l s o lends support t o t h i s explanation,, s i n c e these l a r g e r , doses might f e a s i b l y s t i m u l a t e metabolism of the d i g e s t e d and re s e r v e f a t s so as t o m a i n t a i n the 24 hour b a s a l m e t a b i l i e r a t e , which•would o t h e r w i s e have a tendency t o dr o p , b. A d m i n i s t e r e d b e f o r e F a s t i n g Values i n Table 6, page 42, and graph 6, r e v e a l t h a t t h e B.M.R. i s e l e v a t e d somewhat by the a d m i n i s t r a t i o n of a l / l O g r a i n dose of d e s i c c a t e d t h y r o i d . The maximal v a l u e s were found 24 and 48 hours a f t e r a d m i n i s t e r i n g t h e t h y r o i d . A comparison o f the two drugs i n d i c a t e s t h a t the Parke D a v i s l / l O g r a i n t h y r o i d i s more a c t i v e p h y s i o l o g i c a l l y t h a n t h a t o f Burroughs Wellcome. . The a d m i n i s t r a t i o n o f a s i n g l e dose pf \ g r a i n d e s i c c a t e d t h y r o i d proved e f f e c t i v e i n e l e v a t i n g - the B.M.R. t o a h i g h e r degree t h a n the l / l O g r a i n t h y r o i d ( c f . T a b l e 7, s page 4 3 ) . T h i s e f f e c t p e r s i s t e d over a p e r i o d o f s i x days a f t e r w h i c h t h e B.M-.R. was found to• r e t u r n t o no r m a l . ; From the r e s u l t s , i t appears that, t h e s i n g l e dose o f l / l O and i g r a i n t h y r o i d , a d m i n i s t e r e d o r a l l y , has a s t i m u l a t o r y e f f e c t , not apparent immediately, on t h e B.M.R. and w h i c h has i t s maximal e f f e c t from 24 t o 48 hours f o l l o w -i n g i t s a d m i n i s t r a t i o n . V i t a m i n s and the T h y r o i d , a. B1,B2,B6. and l / l O g r a i n T h y r o i d The r e s u l t s o f thes e t e s t s t o a s c e r t a i n the e f f e c t s o f tatamins B1,B2 and B6 on the B.M.R. a f t e r i n d u c i n g a h y p e r t h y r o i d c o n d i t i o n , by f e e d i n g l / l G g r a i n t h y r o i d d a i l y , are-shown i n Ta b l e s 9-12,pages 44 and 45,and i n graph 7 * The v i t a m i n s a l t h o u g h g i v e n s i n g l y and at i n t e r v a l s , a p p a r e n t l y had a summation eff.ect i n r e d u c i n g the B.M.R., s i n c e at no time d i d the B.M.R. approach the peak a t t a i n e d a f t e r the I n i t i a l p e r i o d o f f e e d i n g the t h y r o i d (Table 9%. The 'continuous f e e d i n g o f t h e t h y r o i d f o r t h e 46 day p e r i o d a l s o appeared t o have had a cu m u l a t i v e e f f e c t on the weights of the a n i m a l s , s i n c e a t no p o i n t d i d the weights r e t u r n t o normal. R i b o f l a v i n had the most pronounced e f f e c t i n augmenting the weights The r e s u l t s , as judged by the a n t i t h y r o g e n i c e f f e c t o f t h e v i t a m i n s i n c o u n t e r a c t i n g weight l o s s and i n c r e a s e d metabolism may be summed up from Tables $-11 as f o l l o w s : % change i n wt. $change-in B.M.R. B l and' l / l O g . • 1.2 g a i n 12.3 decrease B2 " " - 5.3 " 14.7 " B6 " " 2.8 " 7.2 " l / l O g . t h y r o i d 7.4 l o s s 16.3 i n c r e a s e As t h i s summary shows, a l l t h r e e v i t a m i n s have a l o w e r i n g e f f e c t on t h e B.M.R. i n c r e a s e d 16.3$; above normal. 58. The e f f e c t s o f t h i a m i n e and r i b o f l a v i n were most marked i n t h i s r e s p e c t . The e f f e c t i n c o u n t e r a c t i n g weight l o s s was found to"be s l i g h t i n the case of t h i a m i n e a n d ' p y r i d o x i n e and more marked i n the case.of r i b o f l a v i n , b. B1,B2,B6 and f- g r a i n t h y r o i d The r e s u l t s o b t a i n e d i n t h e s e t e s t s are shown i n Tabl e s 13 - 16,pages 46 and 47 9 and as©- pr-epeHted here i n summary form: Rats g i v e n $c;gange i n wt. % change i n B.M.R. •j- g . t h y r o i d o n l y . 11.7 l o s s 23.4 i n c r e a s e IT g . t h y r o i d and B l 0.0 l o s s .8 decrease ' B2 5.25 g a i n 15.5 decrease " B6 0.84 l o s s 0.0 decrease " B1,B2 & B6 7.80 g a i n 14.5 decrease The a d m i n i s t r a t i o n o f t h e i g r a i n t h y r o i d was found t o e l e v a t e t h e m e t a b o l i c r a t e t o 23.4%' above normal, and .to produce a weight' l o s s o f 11.7%' below normal. These percentages are based on t h e average v a l u e s o b t a i n e d from t h r e e groups of a n i m a l s , c o m p r i s i n g e i g h t e e n r a t s . Compared t o the t h y r o g e n i e e f f e c t r e s u l t i n g from the a d m i n i s t r a t i o n o f the l / l O g r a i n t h y r o i d , i t appears t h a t the i n c r e a s e d h y p e r t h y r o i d c o n d i t i o n i s not p r o p o r t i o n a l t o t h e i n c r e a s e d dose. I t has been r e p o r t e d t h a t much of t h e potency o f the t h y r o i d , g i v e n o r a l l y , I s l o s t i n , t h e g a s t r o - i n t e s t i n a l t r a c t , w h i c h would-make i t d i f f i c u l t t o p r e d i c t the p h y s i o -l o g i c a l a c t i v i t y r e s u l t i n g from a g i v e n dosage. The a n t i t h y r o g e n i e a c t i o n of thiamine and p y r i -d o x i n e wase l e s s e v i d e n t i n these t e s t s . No g a i n i n weight 59. was observed f o r t h i a m i n e , but t h e weight was ma i n t a i n e d a t the I n i t i a l l e v e l . The B.M.R. showed a ..slight r e d u c t i o n of 0.80$ . P y r i d o x i n e was found t o be even l e s s e f f i c i e n t i n c o u n t e r a c t i n g the h e i g h t e n e d metabolism and weight l o s s . As the above t a b l e shows.., no change i n the B.M.R. o c c u r r e d and. t h e r e was a s l i g h t r e d u c t i o n i n weight. R i b o f l a v i n proved t o have t h e g r e a t e s t a n t a g o n i s t i c e f f e c t f o r t h e t h y r o i d a c t i v i t y , l o w e r i n g the m e t a b o l i c r a t e 15.5$ and i n c r e a s i n g t h e weight 5.25$ . The e f f e c t of the a d m i n i s t r a t i o n of the t h r e e v i t a m i n s had a g r e a t e r e f f e c t i n promoting a weight g a i n than when ^ i b o g l a v i n . a l o n e was used, and a n e a r l y p a r a l l e l e f f e c t t o r i b o f l a v i n i n l o w e r i n g the i n c r e a s e d metabolism. Thus t h e t h r e e v i t a m i n s ' a p p e a r e d s y n e r g i s t i c i n augmenting t h e weight and. i n r e d u c i n g the B.M.R. T h i s seems p l a u s i b l e s i n c e these v i t a m i n s were found t o have a complementary e f f e c t when t h e i r g l y c o g e n e t i e f u n c t i o n s were s t u d i e d (^3). D r i l l found an addecf requirement f o r B1,B2 and B6 i n a h y p e r t h y r o i d c o n d i t i o n . No worker has. found a g r e a t e r requirement f o r r i b o f l a v i n than' f o r e i t h e r t h i a m i n e o r , p y r i -d o x ine i n t h i s c o n d i t i o n . The p h y s i o l o g i c a l r e l a t i o n s h i p o f these v i t a m i n s t o h y p e r t h y r o i d i s m remains t o be i n v e s t i g a t e d . The f o l l o w i n g ' e x p l a n a t i o n , though a d m i t t e d l e y s u p e r f i c i a l , i s o f f e r e d because i t i n c l u d e s a few of the known f a c t s . The main storage depot f o r v i t a m i n s Bl,B2 and B6 i n t h e body i s t h e l i v e r . The l i v e r has l e s s c a p a c i t y t o 60. s t o r e B l or B6 t h a n i t has f o r B2 ( 2 4 ) . The l i v e r a l s o shows a g r e a t e r a b i l i t y t o r e t a i n r i b i f l a v i n . S i n ce i n the hyper-t h y r o i d c o n d i t i o n t h e B v i t a m i n r e s e r v e s are q u i c k l y ex-h a u s t e d i n t h e l i v e r , i t might be expected t h a t the r i b o f l a v i n s t o r e s would be d e p l e t e d l a s t . When these v i t a m i n s are g i v e n s i n g l y t o t h e h y p e r t h y r o i d i n d i v i d u a l , t h e body would be expected t o show a g r e a t e r r e t e n t i v e n e s s f o r r i b o f l a v i n , whereas t h i a m i n e and p y r i d o x i n e would be r a p i d l y used and l o s t . . The g r e a t e r r e t e n t i v e n e s s of t h e body f o r B2 may, t h e r e f o r e , i n part v, account f o r i t s g r e a t e r a n t i t h y r o g e n i e a c t i v i t y . C o n t r o l s The: t e s t s on t h e c o n t r o l animals are summarized from Ta b l e s 17 a-e,pages 48 and 49, as f o l l o w s ; No. o f D u r a t i o n of % i n c r e a s e . $ change from Supplement Animals T e s t s / Days i n Weight I n i t i a l B.M.R. B l 4 . 12,13 7.2 6.0 i n c r e a s e B2 4 12,16 11.4 5.1 decrease B6 2 12 3.8 7.5 i n c r e a s e B1,B2 & B6 2 . 1 1 ,. 14.3 4.1 i n c r e a s e No supplement 2 10 4.1 As t h i s summary shows., t h i a m i n e e x h i b i t e d a s l i g h t tendency t o i n c r e a s e t h e w e i g h t j p y r i d o x i n e showed no t e n d -ency t o i n c r e a s e the w e i g h t , as compared t o t h e normal weight c o n t r o l s , and r i b o f l a v i n showed a n o t i c e a b l e i n f l u e n c e on t h e growth. The g r e a t e s t p r o p o r t i o n a t e g a i n was produced by 'feeding a l l t h r e e v i t a m i n s ; s i m u l t a n e o u s l y . The animals showed an u n m i s t a k e a b l e l i k i n g f o r the prepared d i e t s 61. c o n t a i n i n g the v i t a m i n s , s i n c e i t was observed t h a t i t t h i s p r e p a r e d f o o d was g i v e n t o g e t h e r w i t h the r e g u l a r d i e t the f i r s t t o be consumed was the pre p a r e d d i e t . The changes i n t h e B.M.R.s t a b u l a t e d above were computed from v a l u e s o b t a i n e d at the t e r m i n a t i o n o f t h e t e s t p e r i o d s a g a i n s t the i n i t i a l b a s a l v a l u e s . They are not s i g n i f i c a n t , s i n c e f l u c t u a t i o n s o c c u r r e d p e r i d d i c a l l y i n t h e B.M.R.s.throughout the t e s t as Table 17 shows, and can o n l y be t a k e n as s u g g e s t i v e . W i t h th e e x c e p t i o n of r i b o f l a v i n . , t h e v i t a m i n s appeared t o have a s l i g h t s t i m u l a t o r y e f f e c t on the metabolism. An exam i n a t i o n of /7<J-e. the TablesAand graph /3 w i l l show t h a t the v i t a m i n s , however, have no a p p r e c i a b l e e f f e c t on the B.M.R. SUMMARY C e r t a i n f a c t o r s which govern the b a s a l m e t a b o l i c r a t e were s t u d i e d i n o r d e r t o f i n d e x p e r i m e n t a l c o n d i t i o n s under which heat p r o d u c t i o n i n t h e a l b i n o r a t would be m i n i m a l . In r e g a r d t o t h e f a s t i n g metabolism , i t was found t h a t , i n agreement w i t h t h e work o f Kingdon,Bunnel and G r i f f i t h , the m e t a b o l i c r a t e d e c l i n e s from c e s s a t i o n of f e e d i n g t o t h e "20th hour p o s t - a b s o r p t i o n , a f t e r which t h e r e i s an e l e v a t i o n i n the B.M.R. r e a c h i n g maximum a t the 2 4 t h hour f o l l o w e d by a drop t o the 3 0 t h hour. T h i s r i s e a t the 24t h hour was a t t r i b u t e d t o the metabolism of f a t . 62. I n a c c u r a c i e s i n d e t e r m i n i n g the l e n g t h of t h e f a s t i n g p e r i o d can t h e r e f o r e l e a d t o a d i v e r s i t y of r e s u l t s . The heat p r o d u c t i o n o f r a t s f a s t e d 20 hours was found t o be mini m a l between 27"C and 31°C. I t appeared from t h e r e s u l t s t h a t t h e r e was a "low c r i t i c a l " temperature below which t h e metabolism v a r i e s I n v e r s e l y as the e n v i r o n -m ental temperature and a "hig h c r i t i c a l " temperature above w h i c h the e n v i r o n m e n t a l temperature has a thermogenic e f f e c t . V a lues o f t h e B.M.R. i n the f a s t i n g animal showed onl y , a : s l i g h t v a r i a t i o n when determined at 10 A.M. at 12 A.M. and at 3 P.M. The B.M.Rs o f r a t s s i x weeks of age were found t o d e c l i n e r a p i d l y t o t h e t e n t h week a f t e r w hich t h e y appeared t o become more c o n s t a n t . A s c e r t a i n e d when the r a t s were t w e n t y - e i g h t weeks, the, B.M.R. showed a dro p o f Q% from the t w e l f t h week. The a d m i n i s t r a t i o n of a s i n g l e l / l O g r a i n dose of d e s i c c a t e d t h y r o i d , o r a l l y , was found t o have a s l i g h t s t i m u l a t o r y e f f e c t on t h e B.M.R., n o t i m m e d i a t e l y apparent,, w h i c h reaches maximum i n from one t o two days and s u b s i d i n g towards t h e t h i r d o r f o u r t h day. The s t i m u l a t o r y e f f e c t p e r s i s t e d l o n g e r when a s i n g l e dose of t h e i g r a i n d e s i c c a t e d t h y r o i d was a d m i n i s t e r e d . Repeated d a i l y doses of the t h y r o i d was found t o have a cu m u l a t i v e e f f e c t i n e l e v a t i n g the B.M.R. and produced a weight l o s s . ' The e f f e c t s o f v i t a m i n s B1,B2 and B6, s i n g l y and 63. i n c o m b i n a t i o n , on the B.M.R. of t h e r a t , were s t u d i e d , a t two l e v e l s of t h y r o i d f e e d i n g . U s i n g l / l O g r a i n Burroughs Wellcome d e s i c c a t e d t h y r o i d , a d m i n i s t e r e d d a i l y , the B.M.R. was found t o Inc r e a s e 16.3%. T h i s i n c r e a s e d metabolism was reduced 12.3$ w i t h 1 mg. ( 500 I.U.) t h i a m i n e h y d r o c h l o r i d e per day, 1.4.7$ w i t h 1 mg. of • . • r i b o f l a v i n [ 400 She rman-Bourquin) u n i t s ) per day, and 7.2$ w i t h 1 mg. of p y r i d o x i n e h y d r o c h l o r i d e per day. The l o s s i h we i g h t , amounting t o 7.4$, induced by the t h y r o i d f e e d i n g , was p a r t i a l l y r e g a i n e d when a comb i n a t i o n of each o f these v i t a m i n s was f e d w i t h the t h y r o i d . Thiamine r e s u l t e d i n a weight g a i n of 1.2$ , r i b o f l a v i n , 5 . 3 $ , a n d p y r i d o x i n e , 2.8$ , T h e ; a d m i n i s t r a t i o n o f ^  g r a i n d e s i c c a t e d t h y r o i d d a i l y e l e v a t e d t h e B.M.R. 23.4$ above normal and reduced the, weight 11.7$ below normal. 1 mg. o f B l , admixed w i t h the foo d and \ g r a i n t h y r o i d , m a i n t a i n e d the v/eight a t the hyper-t h y r o i d l e v e l , and had no a p p r e c i a b l e e f f e c t i n l o w e r i n g t h e B.M.R. 1 mg. o f p y r i d o x i n e , p l u s ^ g r a i n t h y r o i d , d i d not a l t e r the metabolic, r a t e and m a i n t a i n e d the weight a t about the h y p e r t h y r o i d l e v e l . 1 mg. of- r i b o f l a v i n , t o g e t h e r w i t h \ g r a i n t h y r o i d , o f f s e t t h e weight l o s s w i t h a g a i n of 5.25$ and dowered the metabolism 15.5$ . Thus r i b o f l a v i n was found t o produce t h e moxst marked a n t i t h y r o g e n i e e f f e c t , b o t h i n o f f s e t t i n g t h e weight l o s s and i n r e d u c i n g the i n c r e a s e d b a s a l metabolism. The a d m i n i s t r a t i o n o f \ g r a i n , t h y r o i d t o g e t h e r 64. w i t h 1 mg. e a c h i o f " a l l e t h r e e o f t h e v i t a m i n s r e s u l t e d i n a weight g a i n of 7.8$ and a r e d u c t i o n i n t h e B.M.R. of 14.5$ s u g g e s t i n g t h a t t h e t h r e e v i t a m i n s have a s y n e r g i s t i c e f f e c t i n c o u n t e r a c t i n g weight l o s s and I n c r e a s e d metabolism due to t h y r o i d f e e d i n g . The a d m i n i s t r a t i o n o f Ihmg*'o£xeach of the v i t a m i n s as supplementary to t h e normal d i e t was found to have no a p p r e c i a b l e e f f e c t on the B.M.R.., though they d i d s t i m u l a t e growth. 65. REFERENCES CITED A l t h a u s e n , T.L. 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