Studies on the Endocrine (IIjuhIs 358 



feedini; (21 per cent, and 84 per cent, of the initial weijjlit). Stoland (25) 

 thouglit that the loss of weii^ht which rats underijo within the first few 

 days is partly due to accidental causes, such as handling;, etc. Hewitt (26) 

 also obtained lo.ss of weiijht in rats as the result of tlu'roid feeding. 

 Schiifer (27) administered a small amount of thyroid (075-lo grm. of 

 fresh sheep-thyroid) to growing rats, and f(jund it to cause both an increased 

 con3um])tion of food and acceleration of growth. Fhe experiments extended 

 over three month.s. In a second paper Hewitt (20) also found that the 

 administration of a small amount (0-25 grm.) of fresh thyroid (ox) caused 

 an increa.se of weight in rats, accompanied by increase of appetite and food 

 consumption. But when 05 grm. of fresh ox-thyroid was administered to 

 adult white rats it produced lo.ss of weight, the loss becoming greater as 

 the amount of thyroid was increased, and being accompanied and possibly 

 caused by diminution of appetite and lessened consumption of food. 



The above results appear to show that the effects of thyroid feeding 

 upon metabolism depend partly upon the amount of thyroid administered 

 and partly upon the duration of the feeding ; perhaps also upon the 

 amount of active substance contained in the thyroid employed. 



Castration. — Loewy and Riciiter (28) found in dogs that after 

 castration there was a decrease in the amount of oxygen absorbed, this 

 being more marked in females than in males. It was followed by laying 

 on of fat. The result was confirmed by Pachtner (29), but according to 

 Liithje (30) and Zuntz (31) there are occasionally found cases in which 

 fat is not laid on. The experiments of Rovinsky and Schneider relat- 

 ing to the efiects of castration after thyroidectomy have already been 

 mentioned. Shebuneff (32) obtained after castration in males (dogs and 

 rabbits) an increase in body-weight and a diminution in the amount of 

 nitrogen in the urine (decrease of protein oxidation). In most cases he 

 noticed a decrease of COg output and of Og intake. Cramer and M'Call 

 (33) studied the gaseous exchanges during five days of thyroid feeding. 

 During the first two or three days the changes were slight, but after that 

 time there was a considerable increase in CO.2 excretion and oxygen 

 absorption. When thyroid feeding was discontinued the gaseous meta- 

 bolism returned gradually to the normal condition. The diet which they 

 employed was one rich in carbohydrates (bread and milk). The amount 

 of thyroid given was about 1 grm. of dried thyroid per diem, 



I may now proceed to give in detail the results obtained in the course 

 of my own experiments upon rats. 



Present Observations. 



Nitrogen and Calcium Metabolism. 



The animals employed in these experiments were adult white rats : three 

 were females, all the rest males. They were kept in the special metabolism 



