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Abstract

Chum salmon eggs were immersed in thyroxine, in thiourea, in halide salts, and in adrenalin on the day of fertilization and were maintained in these solutions until several months after hatching. All treatments affected growth either favourably or adversely, but only thyroxine and chloride changed body proportions. The changes due to chloride were significantly smaller than those following thyroxine treatment, and it is postulated that they are not “thyroxine-like” in nature. Thiourea inhibited colloid function with the usual hypertrophy and hyperplasia of the gland. Chloride and bromide depressed the heart rate significantly, whilst the other treatments had no effect. Iodide and bromide dispersed melanin pigment but thyroxine concentrated it slightly and adrenalin maximally so that adrenalin treated live fish were very pale. Thyroxine increased markedly the deposition of guanine and must, therefore, accelerate the hydrolysis of nuclear purines. It is concluded that specific effects produced by thyroxine in developing chum salmon are not duplicated by the halides and adrenalin.