406 



W. W. SWINGLE 



TABLE 5 

 Mmj 18 



remained near the surface of the containers. The hind limbs 

 were small, and as yet they had not differentiated into their two 

 primary divisions with toe points. 



These animals revealed clearly all of the symptoms of hyper- 

 thyroidism, the reaction to which is characteristic in this 

 species. Examination of the controls showed none of these 

 changes. None of the animals had limb buds. 



April 17. On this date the differences between iodin-fed and 

 control larvae were marked. All of the body changes noted on 

 April 11th were now much more obvious. The tails of the iodin- 

 fed animals were undergoing atrophy; the hind limbs were plainly 

 visible and had differentiated toes. The total length of the ani- 

 mals had decreased owing to tail resorption (table 7). There was 

 great mortality among the larvae of the iodin culture. Out of 



