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weight during 10 (lays following hypopliysectoniy in the pigeon, and also cytological evidence of stimulation in their cortical cells, are found to agree satisfactorily with Moon's method of assay of adrenocorticotropin in 21-day rats. As tested by these 3 methods the ability of pituitary extracts to stimulate cortical tissue is independent of their prolactin. FSH and thyrotropin potencies. Gamone stimulates both cortical and medullary tissue in both normal and hypophysectomized pigeons. Estrone stimulates cortical tissue a t least in intact birds. Thyroxine, plus vitamin supplements, gave evidence of ability to stimulate cortical tissue in hypophysectomized pigeons.\\-e observed that rats fed our standard adequate. varied diet, supplemented with 100 gamma of vitamin B, daily, either in the form of yeast, or as synthetic vitamin B, (parenterally administered). demonstrated after one generation interference with lactation. loss of the maternal instinct. cannibalism and progressive loss of fertilit!.' \Vith reduction in the amount of vitamin B, to 40 ganima or the elimination of the supplements of vitamin B, for short periods. normal lactation and normal interest in the young was restored. \Vhen the vitaniin B, content was again increased the same toxic effects were o1)served.t Further study completely confirmed our earlier findings. \\'it11 daily supplements of 60 ganinia of vitamin B,, progressive decrease in fertility also occurred, with a moderate incidence of loss of litters due to cannibalism. After four generations breeding decreased. -* A preliminary note of this work appeared in t Interference witli lactation and rcprodurtion rould not liavr been due to the abseiice of vitamins L1 and L, recently postul:rted by Sakaliara Inukai and Ugilni (Scic/rce. lW3, 87. 372) siiwe ,w:lut i3 :I rich soiiri-e of tl~ese factors.

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