306 Kojima 



feeding with posterior lobe causes a greatly increased quantity to be 

 secreted. The results were much less marked with the posterior lobes of 

 glands which had been preserved for a long time in chloroform. 



Experiments on Thyroid Feeding of Animals other than Rats. 



Several previous workers have investigated the effects produced by 

 thyroid feeding on animals other than rats. The following is a brief 

 summary of their observations : — 



Berkeley (2), administering .5'15 grm. of fresh sheep's thyroid 

 to mice, found that they died in from three to ten days, with emacia- 

 tion, rapid respiration, and tremors. The appetite decreased after 

 two days' feeding, and they lost body-weight. Carlson, Rooks, and 

 M'Kie (3) found that thyroid feeding produced in cats a gradual loss 

 of weight, diminished appetite, and a tendency to diarrhoea and 

 roughening of the fur. The loss in weight was rapidly regained on 

 the cessation of thyroid feeding^. Dogs either maintained their weight 

 or increased it, but as young dogs appear to have been used, the gain 

 in weight may have been due to normal growth. Most of the dogs 

 remained healthy. Rabbits and guinea-pigs fed on thyroid lost 

 weight rapidly. Diarrhoea was an almost constant symptom in the 

 rabbit, less constant in the guinea-pig. These observers also fed 

 chickens with 5 grm. to 6*5 grm. of thyroid for a long period (sixteen 

 to ninety-two days). The general result was that these large doses 

 caused loss of body-weight, and in all, or nearly all, toxic symptoms. 

 They found carnivorous animals much more resistant than others, 

 and correlate this with the higher percentage of protein in the 

 food, sugcresting: that omnivorous and herbivorous animals which are 

 accustomed to take less protein may be adversely affected by the 

 addition of the amount of protein contained in the thyroid substance 

 administered. The experiments of Caldwell (4) furnish evidence 

 of the high resistance of dogs and cats to the specific autacoid of the 

 thyroid. He suggests that the fatal results in rabbits might be due 

 to susceptibility to foreign protein ; but this seems improbable from 

 the observ^ations of French (5), that although ox-thyroid is poisonous 

 to rabbits and guinea-pigs, a similar amount of material from the 

 other organs of the ox produces no toxic symptoms. It is certain 

 that the effects which have been produced in my experiments, 

 especially the karj'okinetic changes in the pancreas of the rat and 

 the striking diminution of zymogen granules in all animals, cannot 

 be due merely to excess of protein, for some of the controls received 

 a large proportion of lean meat, and in these the pancreas remained 

 perfectly normal. 



The following are the results of my own observations : — 



Effects of Thyroid Feeding on Mice. 



Two full-grown male mice (Xos. 1 and 2), weighing 25 grm. and 

 22 grm. respectively, were fed with 0'2 grm. of dry ox-thj^roid per mouse 

 per diem added to the ordinary rusk paste. The feeding was continued 



