UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Cytology of a fertile monoploid tomato Hillary, Bertrand Bristow 1936

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
831-UBC_1936_A8_H55_C9.pdf [ 4.02MB ]
Metadata
JSON: 831-1.0105530.json
JSON-LD: 831-1.0105530-ld.json
RDF/XML (Pretty): 831-1.0105530-rdf.xml
RDF/JSON: 831-1.0105530-rdf.json
Turtle: 831-1.0105530-turtle.txt
N-Triples: 831-1.0105530-rdf-ntriples.txt
Original Record: 831-1.0105530-source.json
Full Text
831-1.0105530-fulltext.txt
Citation
831-1.0105530.ris

Full Text

LEh 67. '936 - M S" c?f CYTOLOGY OF A FERTILE MONOPLOID TOMATO. bv B. B. H i l l a r y A T h e s i s s r f k m i t t e d f o r - t h e Degree o f MASTER OF ARTS i n t h e Department of BOTANY THE UNIVERSITY OF BRITISH COLUMBIA September, 1936. T a b l e of C o n t e n t s . Acknowledgment s Page I n t r o d u c t i o n 1 M a t e r i a l and Methods 3 E x p e r i m e n t a l R e s u l t s S o m a t i c chromosome c o u n t s 4 M l c r o s p o r o g e n e s i s 4 Prophase 4 D i a k i n e s i s " 6 Metaphase I 6 Anaphase I "7 I n t e r k l n e s l s ^ V Metaphase I I 8 Anaphase I I . 8 T e l o p h a s e l l 8 P o l l e n t e t r a d f o r m a t i o n 8 P o s s i b i l i t y o f P a r t h e n o g e n e s i s 8 Review o f L i t e r a t u r e and D i s c u s s i o n 9 Summary • 20 B i b l i o g r a p h y 21 D e s c r i p t i o n o f P l a t e s 23 P l a t e I 26 P l a t e I I 27 Acknowledgement s. The w r i t e r w i s h e s t o e x p r e s s h i s thanks t o Mr. W.Mr F l e m i n g f o r s u g g e s t i n g t h i s I n v e s t i g a t i o n and p r o -v i d i n g t h e m a t e r i a l . To Dr.A.H. H u t c h i n s o n f o r A s s i s t a n c e i n t h e c y t o l o g i c a l work and p r e p a r a t i o n of t h e m a n u s c r i p t , and t o Dr.F. D i c k s o n f o r h e l p w i t h p h o t o g r a p h y . CYTOLOGY OF A FERTILE MONOPLOID TOMATO. I n t r o d u c t i o n . The term M o n o p l o i d i s u s e d h e r e r a t h e r t h a n hap-l o i d , not m e r e l y "because i t i s r e p l a c i n g h a p l o i d i n r e c e n t l i t e r a t u r e , b u t because m o n o p l o i d s i g n i f i e s " t r u e h a p l o l d y " ( D a r l i n g t o n , 1932.) Thus t h e s t r a i n o f t h e Ear11 ana v a r i e t y o f tomato u s e d I n t h i s I n v e s t i g a t i o n i s c o n s i d e r e d t o be a m o n o p l o i d , s i n c e i t i s n a t u r a l l y o c c u r i n g , has t w e l v e chromo-somes or t h e b a s i c number o f t h e genus, i n s o m a t i c c e l l s as w e l l as I n the gametes. The p o l l e n i s h i g h l y f e r t i l e and o v u l e development i s a p p a r e n t l y p a r t h e n o c a r p i c r e s u l t i n g i n abundant f r u i t w i t h v i a b l e s e e d s . T h i s i s t h e f i r s t h i g h l y f e r t i l e m o n o p l o i d tomato t o be r e p o r t e d , and as f a r as c a n be a s c e r t a i n e d the f i r s t f e r t i l e m o n o p l o i d f l o w e r i n g p l a n t . The o b s e r v a t i o n s t o be r e p o r t e d I n t h i s p a p e r a r e p a r t o f a s e r i e s o f I n v e s t i g a t i o n s c a r r i e d on f o r t h e p a s t t e n y e a r s a t t h e D o m i n i o n E x p e r i m e n t a l S t a t i o n a t Summerland, B r i t i s h C o l u m b i a , I n an a t t e m p t t o d e t e r m i n e t h e cause o f r o u g h n e s s i n t h e E a r l i a n a t o m a t o . A r o u g h f r u i t may be d e s -c r i b e d as one, w h i c h , i n s t e a d o f h a v i n g a r e g u l a r smooth and ro u n d shape, i s I r r e g u l a r I n shape,- t h a t i s w i t h c o r r u g a t i o n s and g r o o v e s . These r o u g h f r u i t s a r e r e j e c t e d by t h e c a n n e r s , r e s u l t i n g i n s e r i o u s l o s s e s t o t h e g r o w e r s . B r e e d i n g , s e l e c t -i o n , and n u t r i t i o n a l s t u d i e s have b e e n o f no a v a i l i n the e l i m i n a t i o n of r o u g h n e s s . Temperature, e s p e c i a l l y the c o l d - - -2- . night temperatures of the early summer seem- to have -some e f f e c t , giving an increase i n the anaaount of -roughness.-- -Besides cold the other main factor influencing roughness i s heterozygosity i n the plants 3 .a condition which i s i n accord w i t h our present day knowledge of KionoploS ds. To date, cytological study has not contributed greatly to the explanation and. solution of roughness, as only roierosporogenesis has been thoroughly investigated. However, this process i s of interest since i t d i f f e r s fro:a that described for other raonoploid plants i n that there i s an equal d i s t r i b u t i o n of the chromosomes at the tv/o divisions, v/hich are, i n effect,, two successive mitoses during which each chromosome d i v i d e s twlce. -3-M a t e r i a l and Methods. The m a t e r i a l f o r t h i s i n v e s t i g a t i o n was grown d u r i n g 1933, 1934 and 1935 a t t h e Dominion E x p e r i m e n t a l S t a t i o n , Summerland, B.C. Two s t r a i n s o f t h e E a r l i a n a v a r i e t y were u s e d ; A common d i p l o i d v a r i e t y , J o h n B a e r , was u s e d f o r com-p a r i s o n . Buds and b l o s s o m s were c o l l e c t e d a t random t h r o u g h -out t h e f i e l d p l o t s i n o r d e r t o i n s u r e t h a t t h e m a t e r i a l was r e p r e s e n t a t i v e o f the v a r i e t y and n o t of one p a r t i c u l a r p l a n t . Two k i l l i n g and f i x i n g s o l u t i o n s were u s e d . One was weak c h r o m - a c e t i c s o l u t i o n ( S c h a f f n e r ' s f o r m u l a ) , a n d t h e o t h e r was an a l c o h o l - a c e t i c f l u i d known as B.C. F i x i n g S o l u t i o n . I t has t h e f o l l o w i n g c o n s t i t u e n t s : - 95 p e r c e n t a l c o h o l , 100cc; a c e t i c a c i d ( g l a c i a l ) , 2 c c j f o r m a l i n , 5 c c ; and w a t e r , 25 c c . B o t h c a u s e d some p l a s m o l y s i s b u t t h e B.C. F i x a t i v e was t h e s u p e r i o r , and was v e r y c o n v e n i e n t b e c a u s e m a t e r i a l c o u l d be l e f t i n i t f o r an i n d e f i n i t e l e n g t h o f time. The m a t e r i a l was imbedded i n p a r a f i n and s e c t i o n s were c u t 8 t o 10 m i c r o n s i n t h i c k n e s s and s t a i n e d w i t h i r o n alum and a h^ema t oxy l i n. A n t h e r smears were made w i t h b o t h the m o n o p l o i d and d i p l o i d m a t e r i a l , f i x e d w i t h N a v a s c h i n ' s s o l u t i o n and s t a i n e d w i t h G e n t i a n V i o l e t ( L a Cour, 1931). T h i s method p r o v e d q u i t e s a t i s f a c t o r y b u t t h e p a r a f i n method was u s e d a l m o s t e n t i r e l y as i t gave s e r i e s o f s t a g e s i n s i n g l e a n t h e r s . -4-E x p e r i m e n t a l R e s u l t s . S o m a t i c chromosome c o u n t s . Chromosome c o L i n t s wee made i n r o o t tip c e l l s o f t h e m o n o p l o i d E a r l i a n a tomato and t w e l v e chromosomes or t h e x number were o b s e r v e d . ( F i g . 1 ) . I n o r d e r t o be s u r e t h a t e a c h b u d u s e d f o r r n i c r o s p o r o g e n e s i s s t u d i e s was a m o n o p l o i d , chrome-some c o u n t s were made i n s o m a t i c c e l l s o f t h e s e p a l s , p e t a l s , a n t h e r s , and s t y l e . F i g . 2 shows a metaphase p l a t e i n a p e t a l c e l l ; F i g . 3 shows a s i d e v i e w o f metaphase chromosomes of t h r e e l e v e l s o f a n u c l e u s i n an a n t h e r t i p c e l l ; and F i g . 4 shows a l a t e . a n a p h a s e s t a g e i n a c e l l o f t h e s t y l e . A l l s t a g e s show t w e l v e chromosomes w h i c h i s the m o n o p l o i d number f o r t h e tomato. M i c r o s p o r o g e n e s i s . I n t h e f o l l o w i n g d e s c r i p t i o n o f m i c r o s p o r o g e n e s i s I n t h e m o n o p l o i d , terms u s e d t o d e s c r i b e s t a g e s a n a l o g o u s t o t h o s e o c c u r i n g i n the d i p l o i d , p a r t i c u l a r l y t h e p r o p h a s e s t a g e s , w i l l be p l a c e d i n q u o t a t i o n marks t o show t h a t t h e y a r e n o t s t r i c t l y a p p l i c a b l e h e r e . The n u c l e u s a t t h e l a s t r e s t i n g s t a g e p r e c e d i n g m e i o s i s I n t h e m i c r o s p o r o c y t e s c o n s i s t s o f a f i n e r e t i c u l u m of c h r o m a t i c s u b s t a n c e . S c a t t e r e d a l o n g t h i s r e t i c u l u m a r e an i n d e f i n i t e number o f d a r k s t a i n i n g b o d i e s ( F i g . 5 ) . W i t h t h e b e g i n n i n g o f t h e e a r l y p r o p h a s e t h e number of a n a s t o m o s i n g r e t i c u l a r t h r e a d s becomes g r e a t l y r e d u c e d . Those r e m a i n i n g t h i c k e n s l i g h t l y , f o r m i n g s i n g l e l e p t o t e n e t h r e a d s w h i c h a r e j o i n e d t o g e t h e r by f i n e r s t r a n d s ( F i g . 6 ) , Sometimes t h e rema i n s o f the c h r o m a t i c b o d i e s t h a t were: s c a t t e r e d on the r e t i c u l u m a r e s t i l l p r e s e n t , b ut t h e s e d i s a p p e a r l a t e r . A t l a t e l e p t o t e n e the t h r e a d s become a l i t t l e t h i c k e r and t h e f i n e c o n n e c t i n g f i b r e s become l e s s d i s t i n c t , ( F i g . 7 ) . As t h e p r o p h a s e p r o g r e s s e s t h e t h r e a d s c o n t i n u e t o t h i c k e n and show c o n s i d e r a b l e v a r i a t i o n i n d i a m e t e r ( F i g . 8-$-. T h i s c o r r e s p o n d s t o z y g o t e n e a t w h i c h s t a g e s y n a p s i s n o r m a l l y t a k e s p l a c e . The c o n t r a c t i o n known as s y n i z e s i s has not b e e n o b s e r v e d i n t h i s m o n o p l o i d a l t h o u g h some cnn-t r a c t i o n o f the n u c l e a r c o n s t i t i e n t a t a k e s p l a c e . I t i s p r o b a b l y an a r t i f a c t c a u s e d by f i x a t i o n . A t l a t e " z y g o t e n e " t h e r e i s no e v i d e n c e o f p a i r i n g between t h e chromosomes o r any p a r t o f them as would be e x p e c t e d i n a d i p l o i d . The n e x t s t a g e i s "pachytene"where t h e chromosomes h t h i c k e n a n d b e g i n t o s o r t e n i n l e n g t h . A g a i n t h e y show a e v i d e n c e o f h a v i n g p a i r e d ( F i g . 9 ) , " D i p l o t e n e 1 1 , where i n n o r m a l d i p l o i d m e i o s i s I t i s customary f o r t h e chromosomes t o s h o r t e n and t h i c k e n and f o r l o o p s t o o c c u r between t h e p a i r e d p a r t s . Whereas i n t h e m o n o p l o i d E a r l i a n a t h e r e i s s h o r t e n i n g and t h i c k e n i n g o f t h e chromosomes but no l o o p i n g , - a f u r t h e r e v i d e n c e t h a t no p a i r i n g t o o k p l a c e . F i g u r e s 10 and 11 show two c o n s e c -u t i v e s t a g e s o f t h i s . The f i n e c o n n e c t i n g f i b r e s a r e s t i l l p r e s e n t but t h i s i s the l a s t s t a g e a t which t h e y were:seen. F i g . 10 A. shows a s p e c i a l case o f a n u c l e u s a t " d i p l o t e n e " . N u c l e i o f t h i s s o r t o c c a s i o n a l l y o c c u r and t h e p a r a l l e l p o s i t i o n o f some o f the t h r e a d s and chromosomes might e a s i l y he I n t e r p r e t e d t o "be t h e r e s u l t o f p a i r i n g , h u t n o t h i n g was -o b s e r v e d p r e v i o u s t o t h i s s t a g e t h a t would s u b s t a n t i a t e t h i s . P e r haps i t i s an a c c i d e n t a l p a r a l l e l i s m or e l s e t h e chromos-omes a r e b e g i n n i n g t o f o r m d a u g h t e r c h r o m a t i d s . At " d i a k l n e s i s " t h e chromosomes p r e s e n t an un-e x p e c t e d a p p e a r a n c e . They a r e " d o u b l e d " . A p p a r e n t l y a l o n g i t u d i n a l s p l i t t i n g has t a k e n p l a c e g i v i n g them an a p p e a r -ance s i m i l a r t o t h a t o f t h e p a i r e d chromosomes o f a d i p l o i d , b u t i n s t e a d of b e i n g i n t h e f o r m o f t e t r a d s t h e y a r e d i a d s , and t h e number o f d i a d s i s 12. I n d i v i d u a l i t y o f t h e chromo-somes i s p r o m i n e n t a t t h i s s t a g e , b u t t h e y do n o t p o s s e s s t h e same c h a r a c t e r i s t i c s as t h o s e o f t h e u s u a l d i p l o i d tomato. The s p l i t u n i v a l e n t s a r e s c a t t e r e d t h r o u g h o u t t h e n u c l e u s and one n o t i c e a b l e f e a t u r e about them i s t h a t t h e u n i v a l e n t h a l v e s w i d e l y r e p u l s e e a c h o t h e r t o v a r y i n g e x t e n t s b ut t h e y a r e n o t e n t i r e l y s e p a r a t e d and w a n d e r i n g ( F i g . 1 2 ) . D u r i n g l a t e " d i a k i n e s i s " t h e u n i v a l e n t h a l v e s draw t o g e t h e r and t h e n u c l e o l u s and n u c l e a r membrane d i s a p p e a r ( F i g . 1 3 ) . T h i s c o m p a c t i n g p r o c e s s c o n t i n u e s u n t i l t h e chromosomes become rou n d e d and s h r u n k e n t o f o r m s m a l l s p h e r e s l o s i n g t h e i r I n -d i v i d u a l i t y e n t i r e l y . Now a metaphase p l a t e I s formed a t w h i c h t h e s p l i t i n t h e g r e a t l y c o n t r a c t e d chromosomes c a n be o b s e r v e d o n l y w i t h d i f f i c u l t y , ( F i g . 1 4 ) . At metaphase o f the f i r s t d i v i s i o n t h e chromosomes l i n e up r e g u l a r l y a t the e q u a t o r i a l p l a t e and a b i - p o l a r s p i n d l e i s always p r e s e n t . I n e a r l y anaphase t h e t w e l v e d a u g h t e r u n i v a l e n t s ( o r h a l v e d u n i v a l e n t s ) p a s s r e g u l a r l y t o e a c h p o l e ( F i g . 1 5 ) . I n a few odd c a s e s as shown i n F i g u r e ,16 t h e d i v i d i n g u n i v a l e n t s a r e s c a t t e r e d on the s p i n d l e , a r e g u l a r metaphase p l a t e not b e i n g f o r m e d i n t h e s e c a s e s . F i g u r e 17 shows the i n d i v i d u a l i t y o f t h e 12 chromosomes a t " d i s j u n c t i o n " d u r i n g T i r s t metaphase, e l e v e n o f w h i c h show v a r y i n g d e g r e e s o f t e l o m i t i c or t e r m i n a l s p i n d l e a t t a c h m e n t , and t h e o t h e r one a t e l o m i t i c a t t a c h m e n t , t h e s p i n d l e b e i n g a t t a c h e d t o t h e c e n t r e o f t h e a r c - s h a p e d chromosome. At e a r l y anaphase t h e s e chromosomes do not p u l l a p a r t i n t h e f o r m o f V's as i s c h a r a c t e r i s t i c o f p a i r e d d i p l o i d chromosomes. L a t e anaphase shows 12 chromosomes moving r e g u l a r l y t o each p o l e ( F i g . 1 8 ) . At t e l o p h a s e 1 t h e chromosomes mass t o g e t h e r i n a l o o s e a g g r e g a t i o n ( F i g . 1 9 ) . At i n t e r p h a s e t h e r e i s a d e f i n i t e r e o r g a n i z a t i o n o f the n u c l e u s . F i g u r e 20 shows the two n u c l e i a t e a r l y i n t e r -k i n e s i s . F i g u r e 21 shows a l a t e r s t a g e where t h e n u c l e i a r e comp l e t e w i t h n u c l e o l i and d e f i n i t e chromosomes. The chromo-somes a t t h i s s t a g e shov/ d o u b l e n e s s and i n d i v i d u a l i t y . I t was o b s e r v e d t h a t t h e i n d i v i d u a l i t y o f t h e chromosomes was c o n s i s t e n t and t h e same t y p e s c o u l d be i d e n t i f i e d a t d i a k i n -e s i s , metaphase 1, and i n t e r k i n e s i s , - see f i g u r e s 12, 17, 21, w h i c h a r e p l a c e d s i d e by s i d e t o f a c i l i t a t e c o m p a r i s o n . F o l l o w i n g t h e d o u b l e s t a g e d u r i n g i n t e r p h a s e the chromosomes become s m a l l e r and rounded, t h e n u c l e a r membrane and n u c l e o l u s d i s a p p e a r , and t h e s e c o n d metaphase p l a t e s a r e f o r m e d w i t h w e l l - d e f i n e d s p i n d l e s ( F i g . 2 2 ) . B o t h g r o u p s o f chromosomes d i v i d e s i m u l t a n e o u s l y and pass t o t h e p o l e s i n r e g u l a r l a n d o r d e r l y manner ( F i g . 2 3 ) . At l a t e anaphase the s p i n d l e f i b r e s n e a r t h e p o l e s a r e not c l e a r l y d e f i n e d ( F i g . 2 4 ) . Upon r e a c h i n g t h e i r r e s p e c t i v e p o l e s t h e chromosome g r o u p s a r e s u r r o u n d e d by a n u c l e a r membrane and a n u c l e o l u s a p p e a r s . The chromosomes a t t h i s s t a g e l o s e t h e i r s p h e r i c a l shape and become e l o n g a t e d ( F i g . 2 5 ) . P o l l e n t e t r a d s a r e f o r m e d and t h e s e b r e a k a p a r t and d e v e l o p i n t o p o l l e n g r a i n s . P o l l e n i s about 90 p e r c e n t f e r t i l e a l t h o u g h t h i s f i g u r e v a r i e s f o r d i f f e r e n t buds. T h i s was d e t e r m i n e d f rom c o u n t s made o f h e a v i l y s t a i n e d , w e l l -r o u n d e d f u l l p o l l e n g r a i n s i n v a r i o u s a n t h e r s . P o l l e n germ-i n a t e s r e a d i l y on t h e s t i g m a and the s t y l e i s p a c k e d w i t h p o l l e n t u b e s p a s s i n g down i t . P o l l e n n u c l e i were s e e n t o e n t e r t h e embryo s a c , b u t f e r t i l i z a t i o n was not o b s e r v e d t o t a k e p l a c e , however t h e r e i s not s u f f i c i e n t e v i d e n c e on t h i s p o i n t y e t , and many more embryos w i l l have t o be e x a m i n e d - b e f o r e i t can be p r o v e d t h a t p a r t h e n o g e n e s i s t a k e s p l a c e . Endosperm development- appears n o r m a l b u t t h e r e a r e c e r t a i n p e c u l i a r i t i e s i n t h e embryo dev-elopment t h a t r e q u i r e a g r e a t d e a l more r e s e a r c h b e f o r e i t ca n be d e s c r i b e d c o m p l e t e l y . - S i -Review o f L i t e r a t u r e and D i s c u s s i o n . H a p l o i d s p o r o p h y t e s have been d e s c r i b e d i n e i g h t ^genera o f f l o w e r i n g p l a n t s . D a t u r a , O e n o t h e r a , N i c o t i a n a , T r l t i c u m , G r e p i s , B r a s s i c a , M a t t h i o l a , and Solanum. The hap-l o i d s a r e s m a l l e r t h a n t h e d i p l o i d s , w i t h s m a l l e r c e l l s and c e r t a i n o t h e r a l t e r a t i o n s I n f o r m and c h a r a c t e r . They a r e a l m o s t c o m p l e t e l y s t e r i l e . t h e s e have a p p e a r e d (a) a f t e r c r o s s i n g w i t h a d i s t a n t l y r e l a t e d s p e c i e s , (b) a f t e r s u b j e c t i o n t o c o l d a t t h e t i m e o f f e r t i l i z a t i o n and ( c ) I n t h e tomato, " s p o n t a n e o u s l y " . (Prom a summary o f G a t e s and Goodwin^, 1930) . The m o n o p l o i d E a r l i a n a tomato does n o t c o n f o r m t o any o f t h e above d e s c r i b e d g e n e r a l c h a r a c t e r i s t i c s f o r hap-; l o i d s . T h i s m o n o p l o i d p l a n t i s n o t n o t i c e a b l y s m a l l e r t h a n the d i p l o i d , y e t I t i s s l i g h t l y s m a l l e r . Among t h e most n o t i c e a b l e d i f f e r e n c e s o b s e r v e d i n t h e f i e l d a r e t h e f o l l o w i n g : s l i g h t l y s m a l l e r l e a v e s w i t h edges c u r l i n g Inwards e x p o s i n g l i g h t e r c o l o r e d u n d e r s u r f a c e ; an i n c r e a s e I n the number of f l o r a l p a r t s , u s u a l l y two more p a r t s t h a n i n most d i p l o i d s and o f t e n more t h a n two e x t r a stamens; f r u i t s a r e , as a r u l e , b o r n e i n l a r g e numbers on a t r u s s insfeead o f a h a n g i n g cyme as i s customary f o r o t h e r v a r i e t i e s . The s i z e o f t h e c e l l s i s a p p r o x i m a t e l y mid-way between t h e measurements r e p o r t e d f o r t h e c e l l s i z e o f . h a p l o i d and d i p l o i d tomatoes by Humphrey, (1934). I t a p p e a r s t h a t t h i s m o n o p l o i d o r i g i n a t e d "spon-t a n e o u s l y " . The f o l l o w i n g h i s t o r y I s c o p i e d f r o m U.S.D.A. - 1 0 -M i s c e l l a n e o u s P u b l i c a t i o n No. 160: " E a r - l i a n a was i n t r o d u c e d i n 1900 by t h e f i r m of J o h n s o n and S t o k e s , o f P h i l a d e l p h i a . The o r i g i n a l s t o c k was p r o d u c e d by George S p a r k s , o f Salem, ,N.J. and i s r e p o r t e d t o have been d e v e l o p e d f r o m a s i n g l e p l a n t s e l e c t i o n made i n a f i e l d o f tomatoes grown from s e e d p u r c h a s e d under t h e name o f S t o n e . " The a u t h o r does not know whether a l l E a r l i a n a tomatoes a r e m o n o p l o i d o r i f t h i s c o n d i t i o n o n l y e x i s t s i n t h e s t r a i n s d e v e l o p e d by Mr. W.M. F l e m i n g a t t h e Summerland E x p e r i m e n t a l S t a t i o n and d e s c r i b e d i n t h i s p a p e r . The c y t o l o g y o f t h e m o n o p l o i d E a r l i a n a tomato d i f f e r s f r o m t h a t o f any h a p l o i d p r e v i o u s l y d e s c r i b e d , c e l l i n g and B l a k e s l e e (1927, 1927) g i v e an a c c o u n t o f t h e c y t o l o g y o f D a t u r a h a p l o i d s p r o d u c e d by s u b j e c t i n g the p l a n t s t o low t e m p e r a t u r e a t the t i m e o f f e r t i l i z a t i o n . The 12 chromosomes show no a t t r a c t i o n f o r e a c h o t h e r a t the metaphas o f t h e h e t e r o t y p i c m i t o s i s I n t h e m i c r o s p o r o c y t e s but e i t h e r move a t random t o t h e p o l e s ( i n a s s o r t m e n t s o f 1 and 11, 2 and 10, 3 and 9, 4 and 8, 5 and 7, 6 and 6 ) , or t h e r e may be n o n - r e d u c t i o n . I f t h e r e i s s e g r e g a t i o n t h e g r o u p s o f chromo-somes a f t e r a s h o r t I n t e r p h a s e p a s s t h r o u g h a h o m e o t y p i c r n e t o s i s where e a c h d i v i d e s and the h a l v e s a r e d i s t r i b u t e d i n t h e u s u a l manner. Such m i c r o s p o r o c y t e s f o r m 4 s m a l l m i c r o s p o r e s , u s u a l l y 2 e q u a l and s m a l l e r and 2 e q u a l and l a r g e r . P o l y s p o r e s are d e v e l o p e d when i r r e g u l a r i t i e s d u r i n g anaphase of t h e f i r s t d i v i s i o n g i v e chromosomes Independent o f t h e m a i n g r o u p s and t h e s e o r g a n i z e v e r y s m a l l c e l l s i n -11-a d d i t i o n t o t h e 4 p r i n c i p a l c e l l s . A l l of t h e s e s m a l l g r a i n s c o n s t i t u t e the mass of a b o r t i v e p o l l e n w h i c h i s d e v e l o p e d . N o n - r e d u c t i o n t a k e s p l a c e when t h e 12 chromosomes s p l i t and ,the h a l v e s a r e d i s t r i b u t e d i n two s e t s , 12 12, and two p o l l e n g r a i n s r e s u l t e a c h w i t h the h a p l o i d s e t o f chromosomes. These c o n s t i t u t e t h e good p o l l e n grains 'Which make up about 12 p e r c e n t of t h e t o t a l . The D a t u r a h a p l o i d and E a r l i a n a tomato m o n o p l o i d a r e not s i m i l a r s i n c e i n t h e l a t t e r t h e r e a r e two d i v i s i o n s I n t h e tomato and t h e chromosomes d i v i d e at t h e f i r s t d i v i s i o n as w e l l as a t t h e s e c o n d and 12 h a l v e s p a s s r e g u l a r l y t o t h e p i l e s i n e a c h d i v i s i o n r e s u l t i n g i n f e r t i l e p c h l l e n . o Chipman and Goodspeed (1927) made a c y t l o l g i c a l s t u d y o f m e i o s i s i n t h e m i c r o s p o r o c y t e s o f t h e h a p l o i d f r o m N i c o t i a n a tobacum, v a r . p u r p u r e a , one of t h e two h a p l o i d s r e p o r t e d by C l a u s e n and Mann (19 2 4 ) . Thss h a p l M d h a d 24 chromosomes and was f e m a l e s f e e r i l e b u t some v i a b l e p o l l e n was p r o d u c e d . T h e r e was p a i r i n g o f t h e t h r e a d s b e f o r e s y n -i z e s i s i n t h e d i p l o i d but n o t i n t h e h a p l o i d . S y n i z e s e s i n t h e h a p l o i d i s f o l l o w e d by pachynema and the s i n g l e s pireme t h e n segments i n t o t h e h a p l o i d s e t o f 24 chromosomes. B i p o l a r s p i n d l e s a r e o f t e n f o r m e d r e s u l t i n g I n a random d i s t r i b u t i o n o f t h e 24 chromosomes some o f w h i c h o c c a s i o n a l l y p a s s i n t o t h e c y t o p l a s m . U n i v a l e n t s sometimes d i v i d e d u r i n g the h e t e r o -t y p i c m i t o s i s and when r a r e l y a l l 24 d i v i d e t h e r e r e s u l t s a g i a n t s p i n d l e and t h e f o r m a t i o n o f dyads which m i g h t d e v e l o p I n t o p o l l e n g r a i n s w i t h a f u l l s e t of h a p l o i d chromosomes. -12-Her-e t h e r e i s a d i v i s i o n o f a l l u n i v a l e n t s a t t h e f i r s t d i v i s i o n , h u t t h i s i s not f o l l o w e d by a s e c o n d d i v i s i o n as i n t h e tomato and p o l l e n dyads and not t e t r a d s are formed. A h a p l o i d o c c u r i n g i n a p u r e l i n e o f W. g l u t i n o s a was d e s c r i b e d by Goodspeed and A v e r y ( 1 9 2 9 ) . T h i s p l a n t was one o f a c u l t u r e w h i c h ha d b e e n s u b j e c t e d t o x - r a y s as s e e d -l i n g s but i t s o r i g i n was " s p o n t a n e o u s " and u n c o n n e c t e d w i t h t h e t r e a t m e n t r e c e i v e d . The 12 chromosomes were d i s t r i b u t e d a t random i n p o l l e n m e i o s i s . C l a u s e n and hammerts (1929) c r o s s e d N. L . d i g u l a t a , an a l l a h e x a p l o i d w i t h c a r m i n e f l o w e r s and 36 b i v a l e n t chromo-somes, w i t h t h e p o l l e n o f a f o r m o f N. tabaccum, i d e n t i c a l w i t h v a r . p u r p u r e a e x c e p t i n h a v i n g w h i t e f l o w e r s . The l a t t e r h a d 24 b i v a l e n t s . The F]_, c o n s i s t i n g o f 173 p l a n t s h a d a s i n g l e p l a n t w i t h s m a l l w h i t e f l o w e r s and was i d e n t i c a l i n o t h e r f e a t u r e s w i t h h a p l o i d p u r p u r e a . I t was c o m p l e t e l y s t e r i l e , h a d 24 u n i v a l e n t chromosomes I n i t s p o l l e n mother c e l l s and t h e s e were u s u a l l y d i s t r i b u t e d at random. I n one mother c e l l 19 o f t h e u n i v a l e n t chromosomes were seen t o d i v i d e , w h i l e t h e r e s t s e p a r a t e d , one h a l f - u n i v a l e n t b e i n g f r a g m e n t e d i n t o two. K o s t o f f (1929), o b t a i n e d a h a p l o i d by p o l l i n a t i n g an a b e r r a n t p l a n t o f M c o t i a n a Tabaccum • m a c r o p h y l l a h a v i n g 70-72 chromosomes w i t h p o l l e n o f N. L a n g s d o r f f i i (n - 9 ) . Out o f 1000 s e e d l i n g s one r e a c h e d m a t u r i t y . T h i s was a hap-l o i d L a n g s d o r f f i i , somewhat s m a l l e r t h a n t h e d i p l o i d and h a v i n g 9 L a n g s d o r f f i i chromosomes. I n p o l l e n mother c e l l s -13- -the 9 chromosomes do not f o r m an e q u a t o r i a l p l a t e , but s p r e a d out towards the p o l e s o f t h e s p i n d l e and s e p a r a t e a t random. Sometimes some o f t h e chromosomes d i v i d e i n t h e . f i r s t d i v i s i o n . When a l l t h e chromosomes r e m a i n i n a group a t i n t e r k i n e s i s t h e y a l l f r e q u e n t l y d i v i d e i n t h e se c o n d d i v i s i o n f o r m i n g p o l l e n d y a d s . They may s e p a r a t e i n t o two or more g r o u p s , e a c h o f w h i c h forms i t s own s p i n d l e , w i t h r e s u l t i n g p o l l e n t r i a d s , p e n t a d s o r even o c t a d s . About Q% of t h e p o l l e n a p p e a r s good. W i t h N I c o t i a n a h a p l o i d s , random d i s t r i b u t i o n o f the u n d i v i d e d ' u n i v a l e n t chromosomes seems t o be the g e n e r a l r u l e . Such i s n o t the c a s e i n t h e m o n o p l o i d E a r l i a n a tomato where a l l u n i v a l e n t s d i v i d e at t h e f i r s t d i v i s i o n . G a i n e s and A i s e (1926) o b t a i n e d a h a p l o i d w i t h 21 chromosomes by p o l l e n a t i n g w i n t e r wheat, T r i t i c u m compactum h u m b o l d t i i (42 chromosomes), w i t h A e g i l o p s c y l i n d r i c a . The h a p l M d c o u l d n o t be d i s t i n g u i s h e d f r o m t h e f e m a l e p a r e n t Mo. 128 u n t i l t h e time o f f l o w e r i n g when p e c u l i a r i t i e s c h a r -a c t e r i s t i c o f s t e r i l i t y a p p e a r e d . The p l a n t was about 99.8 p e r c e n t s t e r i l e . There was no p a i r i n g o f chromosomes d u r i n g m e i o s i s i n t h e m i c r o s p o r o p h y t e s b e c a u s e t h e r e were p r o b a b l y t h r e e d i s s i m i l a r s e t s o f 7 chromosomes each. The chromosomes a r e g e n e r a l l y d i s t r i b u t e d i r r e g u l a r l y d u r i n g t h e h e t e r o t y p i c m i t o s i s o r t h e r e may be a m i x t u r e o f the two p r o c e s s e s . The h o m e o t y p i c m i t o s i s c o n t i n u e s the d i s o r d e r l y d i s t r i b u t i o n o f the chrornsomes g i v i n g many I r r e g u l a r i t i e s and forms o f p o l y s p o r y . No normal p o l l e n g r a i n s were o b s e r v e d t o d e v e l o p a l t h o u g h s u c h m i g h t r a r e l y tee f o u n d . P o l l e n mother c e l l s sometimes c o a l e s c e f o r m i n g g i a n t p o l l e n g r a i n s . I n some r e s p e c t s t h i s h a p l o i d r e s s e m b l e s t h e tomato,- the l ^ p l o l d , b e i n g i n d i s t i n g u i s h a b l e f r o m th e o t h e r s , and t h e u n i v a l e n t chromosomes s p l i t t i n g l e n g t h w i s e a t t h e f i r s t d i c i s i o n . However t h i s i s n o t t h e r u l e a s i t i s i n t h e tomato. I n some M a t t h i o l a h y b r i d s , L e s l e y and F r o s t (1928) obt a i n e d i n Fg two extreme d w a r f s , one o f w h i c h was d i p l o i d (14 chromosomes w i t h two e x t r a chromosome f r a g m e n t s , t h e o t h e r h a p l o i d vd-th one s u c h f r a g m e n t . I n some c a s e s t h e r e i s r a n -dom s e g r e g a t i o n o f t h e h a p l o i d chromosomes f o l l o w e d by o t h e r I r r e g u l a r i t i e s . F r e q u e n t l y t h e chromosomes s p l i t and,;s"ep:-r:jG a r a t e ( e x c e p t sometimes t h e e x t r a f r a g m e n t ) t h e h e t e r o t y p i c m i t o s i s e v i d e n t l y b e i n g o m i t t e d . T h i s r e s u l t s i n p o l l e n d y a d s . H o l l i n g s h e a d (1928) d e s c r i b e d two h a p l o i d I n d i v i d -u a l s o f G r e p i s c a p i l l a r i s ( n - 3) among p r o g e n y o f a c r o s s C. c a p i l l a r i s x G. t u t o r em. I t i s n o t c e r t a i n v i/hether c o l d or f o r e i g n p o l l e n i s t h e e x c i t i n g c a u s e f o r t h e h a p l o i d b e i n g f o r m e d . The c y t o l o g y o f the h a p l o i d i s not d e s c r i b e d i n t h i s a r t i c l e , and u n f o r t u n a t e l y t h e 1930 p a p e r by t h i s same a L i t h o r w h i c h d e a l s w i t h t h e c y t o l o g i c a l s t u d y was not a v a i l -a b l e . Emerson (1929) d e s c r i b e s t h e r e d u c t i o n d i v i s i o n i n an a t y p i c a l p l a n t a p p e a r i n g i n the F-^  f r o m the c r o s s O e n o t h e r a f r a n c i s c a n a x t h e h y b r i d f r a n c i s c a n a s u l p h u r e a . The s pireme i n the p o l l e n mother c e l l s o f t h i s h a p l o i d i s not -15-c o n t i n u o u s and p a r a l l e l i s m o f t h e t h r e a d s i s common a t syn-a p s i s . P a i r i n g was s e e n at many s t a g e s "but not as f r e q u e n t l y as i n the d i p l o i d . L a t e r t h e spi r e m e a p p e a r s c o n t i n u o u s and i s thirown i n t o l o o p s , t h e arms o f w h i c h a r e t w i s t e d about e a c h o t h e r . A f t e r s e c o n d c o n t r a c t i o n t h e t h r e a d t h i c k e n s and segments i n t o 7 chromosomes f o r m e d end t o end. Anaphase chromosomes have n o t t h e t y p i c a l v ' s w i t h s p i n d l e f i b r e s a t t a c h e d t o t h e c e n t e r . There i s no s i m i l a r i t y between t h i s a n d t h e tomato as t h e r e i s no p a i r i n g i n t h e p r o p h a s e s t a g e s o f t h e tomato and t h e chromosomes d i v i d e a t t h e f i r s t d i v i s i o n and a r e d i s t r i b u t e d r e g u l a r l y . An a c c o u n t o f a n o t h e r h a p l o i d i n O e n o t h e r a i s g i v e n by D a v i s and l u l k a r n i ( 1 9 3 0 ) . T h i s one I s a h a p l o i d m u t a t i o n i n Oe. f r a n c i s c a n a and i s c a l l e d " p o i n t e d t i p s " . I n t h e p o l l e n mother c e l l s t h e s p i r e m e segments i n t o 7 chromo-somes w l i i c h do not p a i r . I r r e g u l a r d i s t r i b u t i o n o f t h e chromosomes i n t h e h e t e r o t y p i c m i t o s i s ( 6 ^ - 1 ) , (5 A- 2) (4 h 3) g i v e s a mass o f s t e r i l e p o l l e n . F u n c t i o n a l p o l l e n g r a i n s a r e t h e r e s u l t o f t h e m u l t i p o l a r s p i n d l e becoming u n i p o l a r , the 7 chromosomes a l l becoming a t t a c h e d t o t h e s p i n d l e s f i b r e s f r o m t h a t p o l e . The h e t e r o t y p i c m i t o s i s b e i n g o m i t t e d , t h e n u c l e u s I s r e c o n s t i t u t e d and t h e chromosomes s p l i t . T h i s c o r r e s p o n d s t o t h e p e r i o d o f i n t e r k i n d s i s and i s f o l l o w e d by an o r d i n a r y h o m e o t y p i c m i t o s i s i n w h i c h s e v e n chromosomes p a s s t o e a c h p o l e o f c t h e s p i n d l e and a dyad o f p o l l a n g r a i n s i s f o r m e d . Here t h e f o r m a t i o n o f a d y a d of f u l l s i z e d p o l l e n g r a i n s by o m i s s i o n o f the r e d u c t i o n d i v i s i o n i s s i m i l a r t o t h a t -16-f o u n d by B e l l i n g and B l a k e s l e e i n D a t u r a , but i s not a t a l l comparable t o t h e tomato where two d i v i s i o n s o c c u r . Other O e n o t h e r a h a p l o i d s have been r e p o r t e d by U-ates and Goodwin (1930^, Stomps (1930 a and b) and O a t c h e s i d e (1932J. The c y t o l o g y o f t h e s e i s somewhat s i m i l a r t o t h o s e d e s c r i b e d above. A h a p & o i d tomato mutant w i t h 12 chromosomes has b e e n d e s c r i b e d by L i n d s t r o m ( 1 9 2 9 ) . I t a p p e a r e d i n t h e P g numbering 327 p l a n t s o f a v a r i e t a l c r o s s showing complete f e r t i l i t y , and may t h e r e f o r e be r e g a r d e d as s p o n t a n e o u s . I t i s dwarf and c o m p l e t e l y s t e r i l e . I n a c c o u n t o f t h e c y t -o l o g y of t h e h a p l o i d i s g i v e n by L i n d s t r o m and Koos (1931). L i t t l e a t t e n t i o n was g i v e n t o the p r o p h a s e b u t i t was b e l i e v e d t h a t a c o n t i n u o u s s p i r e m e was p r e s e n t . No metaphase p l a t e was formed. D i s t r i b u t i o n was i r r e g u l a r b u t a l l c o m b i n a t i o n s were o b s e r v e d . O c c a s i o n a l m i c r o n u c l e i were p r e s e n t . The r e s u l t s o f c y t o k i n e s i s were n o t u n i g o r m , g r o u p s o f f r o m two t o s i x c e l l s a p p e a r e d . Humphrey (1934) d e s c r i b e s t h e c y t -o l o g y of t h i s p a r t i c u l a r h a p l o i d w i t h s p e c i a l emphasis, on t h e p r o p h a s e , l i e f o u n d s i n g l e l e p t o t e n e t h r e a d s w i t h l a c k of p a i r i n g and t h i c k e n i n g and s h o r t e n i n g o f t h e s e t o form chromosomes w h i c h e x i s t e d as u n p a i r e d u n i v a l e n t s a t d i a k i n e s i s . The a u t h o r ' s o b s e r v a t i o n s o f t h e p r o p h a s e s t a g e s I n t h e mono-p l o i d E a r l i a n a tomato agree v e r y c l o s e l y w i t h t h o s e of Hum-p h r e y . B u t a t d i a k i n e s i s t h e chromosomes o f the E a r l i a n a tomato a r e l o n g i t u d i n a l l y s p l i t and the f i r s t d i v i s i o n i s a r e g u l a r m i t o s i s , I n w h i c h 12 h a l v e d u n i v a l e n t s p a s s t o e a c h p o l e a n d - a r e - d i s t r i b u t e d r e g u l a r l y and -not-at -random as i n the other--haploid.- - -Humphrey -somdtimes -observed -three - s p i n d l e s at t h e s e c o n d - d i v i s i o n w h e r e a s - i n - t h i s m o n o p l o i d - t h r e e were ,never -observed.. A l s o n o r m a l s p o r e s o c c a s i o n a l l y - r e s u l t f r o m n o n - r e d u c t i o n a t the f i r s t d i v i s i o n , and hexads -are o c c -a s i o n a l l y formed, b u t i n t h e E a r l i a n a t e t r a d s * a r e always f o r m e d . .. J o r g e n s e n 1928, g i v e s a n i n t e r e s t i n g d e s c r i p t -i o n -of some Solanum h a p l o i d s . - T h e s e were p r o d u c e d by a t t -empts t o c r o s s two s p e c i e s t h a t w o u l d c r o s s o n l y w i t h d i f f -i c u l t y . -The p o l l e n t i i b e o f Solanum l u t e u m may e n t e r t h e embryo sac o f S. Higrum and d i s c h a r g e i t s two sperm n u c l e i b u t t h e y f a l l t o f u s e - w i t h t h e egg and endosperm n u c l e u s a n d - f i n a l l y d i s i n t e g r a t e . From some of t h e u n f e r t i l i z e d eggs embryos b e g i n t o d e v e l o p and i t i s more t h a n l i k e l y , t h a t t h e seeds w h i c h p r o d u c e h a p l o i d s come f r o m p a r t h e n o -g e n e t i c d e v e l o p m e n t . D u r i n g m e i b s i s i n t h e m i c r o s p o r o . c y t e s t h e 30 chromosomes o f t h e h a p l o i d a t d l a k i n e s i s show some d e g r e e o f p a i r i n g , the number-of p a i r s r a n g i n g f r o m 3 t o 11 or 12, The l a r g e , number o f ; p a i r s s u g g e s t a r e d u c t i o n o f the 12g t 12-j_ t y p e . At t h e h e t e r o t y p i c metaphase o n l y t h e b i -v a l e n t s a r e c o n s t a n t l y p r e s e n t on t h e e q u a t o r i a l p l a t e , t h e u n i v a l e n t s b e i n g s c a t t e r e d t h r o u g h t h e c e l l s and most o f t e n i n t h e p o l a r r e g i o n s . The number of b i v a l e n t s on the p l a t e range f r o m 3 t o 12 w i t h numbers o f 5 t o 8 most f r e q u e n t . U n i v a l e n t chromosomes l y i n g n e a r t h e p l a t e may d i v i d e and t h e i r p r o d u c t s can-be r e c o g n i z e d by t h e i r s m a l l s i z e . The chromosomes p a s s i r r e g u l a r l y t o t h e p o l e s i n numbers r a n g i n g f r o m 15 t o 22 w i t h 18 most -frequent.- The h o m e o t y p i c m i t o s i s more commonly p r e s e n t s 18 chromosomes a t metaphase, t h e s e ^ d i v i d e and anaphase p r o c e e d s r e g u l a r l y g i v i n g 4 p o l l e n g r a i n s u s u a l l y w i t h 18 chromosomes. A s t r i k i n g p e c u l i a r i t y o f t h e Solanum h a p l o i d i s t h e p a i r i n g o f c e r t a i n chromosomes i n the h e t e r o t y p i c m i t o -s i s . T h i s , as J o r g e n s e n (1928) p o i n t s out, s u g g e s t s t h a t the 36 chromosomes o f the h a p l M d c o n s t i t u t e a g r o u p composed of 3 s e t s o f 12, two of t h e s e s e t s c o n t a i n homologues of s u f f i c i e n t s i m i l a r i t y t o b r i n g them t o g e t h e r i n a t r u e s y n -a p s i s . S u ch b e h a v i o r c o u l d n o t be e x p e c t e d t o o c c u r i n the tomato where t w e l v e , t h e h a p l o i d number, i s t h e b a s i c chrome-some number o f t h e genus. J o r g e n s e n f o u n d t h a t p a r t h e n o g e n e t i c embryo de-v e l o p m e n t i n Solanum n i g r u m was the r e s u l t o f a f e r t i l i z a t i o n s t i m u l u s c a u s e d by the n u c l e i f r o m p o l l e n o f d i s t a n t l y r e -l a t e d S. l u t e u m e n t e r i n g t h e embryo sac but f a i l i n g t o f u s e w i t h t h e egg n u c l e u s . " In t h e tomato the p o l l e n tube was seen t o e n t e r t h e embryo s a c and d i s c h a r g e i t s two n u c l e i , t hough t h e y came f r o m the same p l a n t , f u s i o n o f the egg and p o l l e n n u c l e u s was-not o b s e r v e d . Thi's i s a d i f f i c u l t p r o -c e e d u r e t o see a t any t i m e , b u t i t i s a s t i l l more d i f f i c u l t t a s k t o p r o v e t h a t f e r t i l i z a t i o n does n o t t a k e p l a c e , and many more embryo s a c s - w i l l have t o be examined b e f o r e p a r t h -e n o g e n e s i s can be d e f i n i t e l y d e m o n s t r a t e d . I f p a r t h e n o -g e n e s i s i s shown t o t a k e p l a c e I n the tomato and t h e p e c ---• - -19-u l l a r i t i e s o f - t h e e n s u i n g -embryo development - c l e a r e d -up i t the vid.ll e x p l a i n how v i a b l e seeds a r e p r o d u c e d , and how,, l i f e l i f e c y c l e o f t h i s m o n o p l o i d p e r p e t u a t e d . The E a r l i a n a when u s e d i n c r o s s e s w i t h o t h e r t o -matoes seems t o a c t n o r m a l l y . There a r e no a p p a r e n t i r r e g -u l i a r i t i e s i n t h e p r o g e n y o f t h e s e c r o s s e s , b u t as y e t no c y t o l o g i c a l e x a m i n a t i o n o f t h e s e h a s b e e n made. T h i s m o n o p l o i d , t h o u g h t h e r e a r e but one set o f non-homologous chromosomes i n i t s c e l l s , i t i s n o t homo-zygous. T h i s was d e m o n s t r a t e d by Mr. F l e m i n g a t Summerland when he d e v e l o p e d b y s e l e c t i o n ( s e l f - f e r t i l i z a t i o n not b e i n g n e c e s s a r y as t h e tomato i s s e l f - p o l l i n a t e d ) s t r a i n s which were homozygous f o r smooth f r u i t shape. L a t e r t h e s e same s t r a i n s became h o p e l e s s l y r o u g h . T h i s c a n p e r h a p s be ex-p l a i n e d by c o n s i d e r i n g t h a t m u t a t i o n s r e s u l t e d f r o m non-d i s j u n c t i o n , t r a n s l o c a t i o n , or r e d L i p l i c a t i o n o f s m a l l p o r t i o n s of t h e chromosomes o f the m o n o p l o i d as s u g g e s t e d by E a s t (1930) and D a r l i n g t o n (1932). Summary-1. ••• Chromosome c o u n t s made I n t h e c e l l s o f r o o t t i s e p a l s , p e t a l s , a n t h e r s a n d - s t y l e , r e v e a l e d the s o m a t i c num-, b e r o f chromosomes t o be -12, t h e m o n o p l o i d number and the b a s i c number f o r t h e genus. 2. E a r l y p r o p h a s e s t a g e s show s i n g l e l e p t o t e n e t h r e a d s w i t h no p a i r i n g . 3. L a t e r p r o p h a s e s t a g e s show a t h i c k e n i n g and s h o r t e n i n g o f t h e s e t h r e a d s t o f o r m chromosomes, and t h e r e i s no e v i d e n c e of p a i r i n g h a v i n g t a k e n p l a c e . 4. A t d i a k i n e s i s t h e chromosomes a r e :'doubled" due t o a l o n g i t u d i n a l s p l i t t i n g . There a r e 12 d i a d s or 24 monovalent h a l v e s . 5. A r e g u l a r - m e t a p h a s e p l a t e I s f o r m e d and the u n i v a l e n t h a l v e s p a s s r e g u l a r l y t o each p o l e e x a c t l y as I H a h o m e o t y p i c m i t o s i s . 6. A t i n t e r k i n e s i s t h e n u c l e u s i s d e f i n i t e l y r e -c o n s t i t u t e d and t h e chromosomes a p p e a r d o u b l e . 7. The chromosomes show c h a r a c t e r i s t i c i n d i v i d -u a l i t y a t d i a k i n e s i s , f i r s t metaphase d i s j u n c t i o n , and i n t e r -k i n e s i s . 8. The se c o n d d i v i s i o n i s normal i n a l l r e s p e c t s 12 chromosomes p a s s i n g t o each o f t h e f o u r p o l e s . 9. P o l l e n t e t r a d s a r e f o r m e d and t h e r e s u l t i n g p o l l e n i s 90 p e r c e n t f e r t i l e . 10. E v i d e n c e s u g g e s t s p a r t h e n o g e n e t i c embryo dev elopment and t h e s e e d p r o d i i c e d i s about-85 p e r c e n t v i a b l e . -21-B i b l i ography. B e l l i n g , J . y and Blakeslee,-A.:FV, 1925, -The R e d u c t i o n D i v i s i o n i n H a p l o i d , D i p l o i d , ' T r i p l o i d a n d " T e t r a p l o i d D a t u r a s . P r o c . H a t . Aoad.-Sci., 9, 106-111. B e l l i n g , J . , and B l a k e s l e e , A . F . , 1957, The a s s o r t m e n t o f C h r o m o s o m e s - i n - H a p l o i d D a t u r a s . - C e l l u l e , 37,-355-365. C a t c h s i d e , D . G . , '1932, The Chromosomes of a New H a p l o i d O e n o t h e r a . G y t o l o g i a 3. • : Chipman,R. :H., and Goodspeed, T.H. , I n h e r i t a n c e i n N i c o t i a n a Tabacum, V l l l . ; G y t o l o g i c a l F e a t u r e s o f p u r p u r e a h a p l o i d . U n i v . C a l i f . Pub. B o t . 11, 142-158. Cl a u s e n , R . E . , and Lammerts,W/E., 1929, I n t e r s p e c i f i c H y b r i d -i z a t i o n i n N i c o t i a n a X. H a p l o i d and fiiploid Nerogony. - Amer. Na t . 63, 279-282. Cl a u s e n , R . E . , and Mann, -M..C. , 1924, I n h e r i t a n c e I n N i c o t i a n a Tab acuta V. The o c c u r r e n c e o f h p p l o i d p l a n t s i n i n t e r -s p e c i f i c p r o g e n i e s . P r o c . N a t . Acad. S c i . , 10, 120---124. -Davis,B.M.,- a n d K u l k a r n i , C . G . , 1930, The, C y t o l o g y and Gen-e t i c s of a h a p l o i d s p o r t f r o m O e n o t h e r a f r a n c i s c a n a . G e n e t i c s , - 1 5 j 65-80. D a r l i n g t o n , C D . , 1932. R e c e n t Advances I n C y t o l o g y . P. B l a k i s t o n ' s Son and Co. I n c . P h i l a d e l p h i a . -D e s c r i p t i o n o f Types o f P r i n c i p a l A m e r i c a n V a r i e t i e s o f • . Tomatoes; U.S.D.A. M i s s c e l l a n e o u s P u b l i c a t i o n No. 160. E ast,E.M., 1930, -The P r o d u c t i o n o f Homozygotes t h r o u g h • • - i n d u c e d P a r t h e n o g e n e s i s . S c i e n c e 72, 148-149. Emerson,S.H., 1929,. The r e d u c t i o n d i v i s i o n i n a h a p l o i d -Oenothera. C e l l u l e , 39, 159-165. Gaine s , E . P . , and A a s e , H . C , 1926, A h a p l o i d wheat p l a n t . Amer. <T. B o t . , 13, 373-385. Gates,R.R., and Goodwin.K.M., 1930, A new H a p l o i d O e n othera, w i t h some c o n s i d e r a t i o n s on H a p l o i d y i n P l a n t s and A n i m a l s . J. Genet., 23, 123-156. Goodspeed,T.H,, and A v e r y , P . , 1929, The o c c u r r e n c e o f a N i c o t i a n a g l u t i n o s a H a p l o n t . P r o c . Nat. Acad. S c i . 15, 502-504. H o l l i n g s h e a d , L . , 1930, A c y t o l o g i c a l s t u d y o f H a p l o i d C r e p i s S a p i l l a r i s P l a n t s . U n i v . C a l i f . Pub. A g r . S c i . , 6, 107-134. Humphrey, L.M.-, The M e i o t i c D i v i s i o n s o f - H a p l o i d , D i p l o i d and T e t r a p l o i d 1'omatoes w i t h S p e c i a l R e f e r e n c e t o the P r o p h a s e . - G y t o l o g i a 5, No. 3, 278-300. Jorgensen,C.A., 1928, The E x p e r m i n t a l F o r m a t i o n o f H e t e r o -p l o i d P l a n t s i n the Genus Solanum. J . Genet., 19, 133-211. -K o s t o f f . D , , 1929, Am a n d r o g e n i c N I c o t l a n a h a p l o i d . Z e i t s . f . Z d l l f o r s c h , u . m i k r . A n a t . 9, 640-642, Lesley,M.-M. ,- and F r o s t s H . B . , 1928, Two extreme " s m a l l " M a t t h i o l a p l a n t s ; a h a p l o i d w i t h one and a d i p l o i d w i t h two a d d i t i o n a l chromosome f r g g m e n t s . Amer. Nat., 62, 22-23. Lesley,M.M., 1926, M a t u r a t i o n i n D i p l o i d and t r i p l o i d Tomatoes. G e n e t i c s , 11, 267-279. .Lindstrom,E.W., 1929, A h a p l o i d mutant i n t h e tomato. J . , H e r e d . , 20, 23-30. L i n d s t r o m , E.W.~, and Koos, K. , 1931, C y t o g e n e t i c i n v e s t i g a t i o n s o f a h a p l o i d tomato and i t s d i p l o i d and t e t r a p l o i d p r o g e n y . Amer. J . B o t , , 18, 398-410. Sharp,L.W., 1934, I n t r o d u c t i o n t o C y t o l o g y . M c G r a w - H i l l , New Y o r k . Stomps, T . J . , 1930 a, Tiber P a r t h i n o g e n e s i s i n f o l g e F r e m b e f r u e h t u n g b e i O e n o t h e r a . Z.I.A.V., 54, 243-245. Stomps,T.J., 1930 b, Uber P a r t h e n o g e n e t i s c h e O e n o t h e r a . B e r . D e u t s . B o t , Ges., 48, 119-126. -23-D e s c r i p t l o n o f P l a t e s . -A l l - d r a w i n g s w eremade w i t h a camera l u c i d a g i v i n g a m a g n i f i c a t i o n o f 3700- d i a m e t e r s . I n r e p r o d u c t i o n t h e d r a w i n g s were r e d u c e d one h a l f . P l a t e - 1 . • P i g . 1. Metaphase p l a t e i n a r o o t t i p c e l l showing 12 s o m a t i c chromosomes. P i g . 2. Metaphase p l a t e i n a p e t a l c e l l w i t h 12 chromosomes. A d j a c e n t t o i t i s a r e s t i n g n u c l e u s a l s o w i t h 12 chromosomes. F i g . 3. Three l e v e l s o f a n u c l e u s i n an a n t h e r t i p c e l l showing a s i d e v i e w o f t h e 12 chromosomes a t meta-phasw. F i g . 4. L a t e anaphase i n a c e l l o f t h e s t y l e , ,12 chromosomes p a s s i n g t o each p o l e . F i g . 5. M i c r o s p o r o c y t e n u c l e u s a t l a s t r e s t i n g s t a g e p r i o r t o m e i o s i s . F i g . 6. E a r l y l e p t o t e n e , t h r e a d s b e g i n n i n g t o t h i c k e n . F i g . 7. L a t e l e p t o t e n e , s i n g l e t h r e a d s becoming t h i c k e r , t h e c o n n e c t i n g f i b r e s a r e l e s s d i s t i n c t . F i g . 8. "Zygotene" w i t h l a c k o f p a i r i n g between t h e chromosomes. F i g . -9. " P a c h y t e n e " . The chromosomes show no e v i d e n c e o f h a v i n g b e en p a i r e d . F i g . 10. E a r l y " d i p l o t e n e " . The chromosomes l a c k t h e c h a r a c t e r i s t i c l o o p i n g o f p a i r e d p a r t s as i n d i p l o i d s . F i g . 10 A, Some o f t h e chromosomes have t h e app-e a r a n c e o f feeing p a i r e d , h u t t h i s i s - b e l i e v e d t o he a s t a g e i n t h e f o r m a t i o n o f d a u g h t e r c h r o m a t i d s . - • -F i g . 11. S h o r t e n e d and t h i c k e n e d i r r e g u l a r chromosomes o f l a t e " d i p l o t e n e " and d i a k i n e s i s . F i g . 12. D i a k i n e s i s . The chromosomes a r e "doub-l e d " due t o a l o n g i t u d i n a l s p l i t t i n g . The u n i v a l e n t h a l v e s r e p u l s e e a c h o t h e r w i d e l y and show marked i n d i v i d u a l i t y . F i g . 17. S i d e v i e w o f metaphase 1 a t t h e time o f d i s j u n c t i o n . The chromosomes a r e s e p a r a t e d i n the draw-i n g i n o r d e r t o b r i n g out t h e i r i n d i v i d u a l i t y , - F i g . 21. I n t e r k i n e s i s . Note t h a t c e r t a i n i n -d i v i d u a l chrome somes c a n be p i c k e d out a t t h i s s t a g e , d i a k i n e s i s , and metaphase.-F i g . 13. L a t e d i a k i n e s i s . The u n i v a l e n t h a l v e s of t h e d i a d s a r e - d r a w i n g c l o s e r t o g e t h e r and t h e n u c l e o l u s has d i s a p p e a r e d "accompanied by t h e breakdown of the n u c l e a r membrane. F i g . 15. E a r l y anaphase 1, d a u g h t e r u n i v a l e n t s p a s s i n g r e g u l a r l y t o p o l e s . F i g . 16. E x c e p t i o n a l c a s e where a r e g u l a r e q u a t o r i a l p l a t e i s n o t formed. F i g . 18, La'te anaphase, 12 chromosomes p a s s i n g t o e a c h p o l e . F i g . 14. Metaphase p l a t e of f i r s t d i v i s i o n w i t h c o n t r a c t e d s p h e r i c a l chromosomes. - • -25- -F i g . 19. T e l o p h a s e 1. -- - F i g . 20. E a r l y - i n t e r k i n e s i sy t h e -chromosomes have n o t y e t a c q u i r e d t h e i r - c h a r a c t e r i s t i c shapes. F i g . 22. Metaphase-11. F i g . - 23. E a r l y anaphase 11, t h e chromosomes i n d i c a t e t h a t a r e g u l a r d i v i s i o n h a s t a k e n p l a c e . F i g . 24. L a t e anaphase 11, 12 chromosomes ^ p a s s i n g t o e a c h of t h e f o u r p o l e s . F i g . 25. F o u r n u c l e i r e s u l t f r o m the s e c o n d d i v i s i o n . F i g . 26. T e t r a d o f p o l l e n g r a i n s . -26-11ate 1. 17 12 -27-P l a t e 1 1 . 

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
https://iiif.library.ubc.ca/presentation/dsp.831.1-0105530/manifest

Comment

Related Items