Thyroidectomy and Thyroid Feeding in Rabbits. 67 



10 per cent. The whole series of females composed of ten spayed 

 and eleven controls gave an average for the operated animals of 

 16.35 m S- an d for the controls 13.71 mg. or a gain of 18 per cent. 

 The curves of growth from this grouping are essentially the same 

 as by the grouping just mentioned. 



From these results it would seem that the apparent increase 

 in weight of the pituitary after castration in case of the male rab- 

 bits should be entirely neglected, since it is no more than would be 

 readily shown by two groups of normal animals. In case of the 

 females of the second series the increase in weight of the pituitary 

 of the spayed rabbits, although not marked, is quite distinct, and 

 is accompanied by no response in overgrowth of body weight as 

 is shown in case of the males. 



40 (857) 



Effect of thyroidectomy followed by thyroid feeding on weight of 

 pituitary in rabbits. 



By A. E. Livingston. 



[From the Physiological Laboratory, Medical College, Cornell 

 University, Ithaca, N. Y.] 



The object of this experiment was to determine the effect 

 upon the weight of pituitary in the rabbit following the adminis- 

 tration of sheep's thyroid. Both males and females were used. 

 The male rabbits were divided into two groups. The animals of 

 one were thyroidectomized and those of the other used as controls. 

 To one half of the thyroidectomized animals and one half of the 

 control group a capsule containing one tenth of a gram of Armour 

 and Company's desiccated sheep's thyroid was administered on 

 alternate days. The females were treated in precisely the same 

 manner and thus each sex was composed of animals under four 

 conditions: first those which were entirely normal, second those 

 normal and fed thyroid, third those thyroidectomized and not fed 

 thyroid, and fourth thyroidectomized and fed thyroid. 



The males and females were kept separate but under the same 

 conditions and each animal was weighed once a week. All the 

 animals were killed at the end of about six months after operation 



