600 JAMES B. ROGERS 



COMPARISONS OF THE ANTERIOR LOBE OF THE PITUITARY GLAND 

 AND OF THE THYMUS GLANDS IN YOUNG SEXUALLY MATURE 

 FROGS AND THYROIDLESS TADPOLES KILLED BETWEEN DE- 

 CEMBER 15, 1915 AND MARCH 3, 1917 



The thyroidless tadpole 7, table 2, killed December 15, 1916 

 had a body length of 33 mm. The pituitary gland was repre- 

 sented by 950 and the thymus gland by 575. 



The thyroidless tadpole 8, table 2, killed February 7, 1917, had 

 a body length of 43 mm. and was the largest of the thyroidless 

 specimens. The pituitary gland was represented by 935 and 

 the thymus gland by 1219 on the relative standard. The 

 thyroidless tadpole 9, killed February 22, 1917, had a body 

 length of 34 mm. The pituitary gland was represented by 520 

 and the thymus gland by 940, table 2. The thyroidless tadpole 

 10, table 2, killed March 3, 1917, had a body length of 40 mm. 

 The pituitary gland was represented by 911 and the thymus 

 gland b} r 475. The pituitary gland of this specimen was larger 

 than that of the February 22, table 2, no. 9, specimen but smaller 

 than of the February 7, table 2, no. 8, thyroidless tadpole. The 

 thymus glands of this specimen were smaller than those of the 

 other two thyroidless specimens killed a little earlier. There are 

 not sufficient grounds however to say that the thymus glands 

 are degenerating. 



The controls for these older thyroidless tadpoles were a num- 

 ber of young sexually mature frogs that metamorphosed the 

 preceding summer and were killed. February 18 to March 

 4. The average volume of the pituitary gland for this class of 

 controls was 416, table 2. The pituitary gland in each of the 

 four oldest thyroidless specimens was larger than in the controls. 



The pituitary glands of the four oldest thyroidless tadpoles 

 are represented by 950, 935, 520 and 911 respectively, table 2. 

 It is apparent here that the pituitary gland in the thyroidless 

 tadpoles grew larger than did the pituitary in young sexually 

 mature frogs. This was especially noticeable when corrections 

 were made for relative body length. It is remarkable, for the 

 thyroidless specimens were still in the tadpole stage while the 

 frogs had metamorphosed the preceding summer. 



