512 BENNET M. ALLEN 



starvation tadpole which was just as old and was killed 15 days 

 later. Text figures 4, 5, and 6 serve to show the relative degree 

 of development of the testes in a well fed thyroidless specimen, 

 in a normal young frog killed slightly later, and in an otherwise 

 normal tadpole that had been subjected to extreme inanition, 

 respectively. This comparison is quite instructive. It has been 

 shown by Swingle, whose paper appears in this journal, that the 

 germ glands are greatly retarded in their development by poor 

 feeding. If the failure of the thyroidless tadpoles to metamor- 

 phose might by some be attributed to inanition, it is possible to 

 refute such an explanation by pointing to the full development 

 of the gonads in the thyroidless specimens, and to the remarkably 

 low development of the testes in this starved specimen which, 

 by the way, had limbs reaching the maximum length of those 

 of the thyroidless tadpoles. When we take into consideration 

 the transformation of the controls kept and fed under identical 

 conditions, the case is seen to be definitely established. 



The development of the ovaries and oocytes in the thyroidless 

 tadpoles is equally marked as shown in table 4 : 



The ovaries show similar conditions, in that they develop in 

 an altogether normal fashion and at a normal rate. 



Tadpole FT2 had been fed a thyroid preparation for four days 

 prior to being killed. This has not appreciably modified the 

 gonads, hence it is classed along with the other thyroidless tad- 

 poles. Rough estimates of the dimensions and volume of the 

 ovaries were made. These were by no means so accurate as 

 those made in the case of the testes. It is easy to see why the 

 evident irregularity of the ovaries (text figures 7 and 8) should 

 make this nothing but a crude approximation. Nevertheless, 

 these estimates serve as a very good basis of comparison. In the 

 cases of FC1, FC2, FC3, FC4, FT1, FT2 and FT3 : all three di- 

 mensions were secured. The length was calculated by counting 

 the number of sections of known (10 mm.) thickness. Width 

 and thickness were measured by taking an average of eye piece 

 micrometer measurements made upon every tenth section in the 

 series. 



