RELATION OF GLANDS TO IODINE AND METAMORPHOSIS. 409 



the base line. Dots are used to designate control, normal tad- 

 poles; crosses designate the pituitaryless tadpoles just before 

 the administration of iodine while crosses within circles indicate 

 the pituitaryless tadpoles at the end of the period of iodine 

 feeding. It appears that the pituitaryless tadpoles at the be- 

 ginning of the experiment are at this stage already commencing 

 to undergo a retardation in hind leg growth as compared with 

 the normal controls. In the iodine fed, pituitaryless tadpoles 

 the reduction in body length together with an actual and relative 

 increase in leg length are clearly evident. 



The next series of experiments involved feeding iodine in the 

 same manner to tadpoles from which both the pituitary and thy- 

 roid glands had been removed. In this case, tadpoles were kept 

 separated in different dishes so that it was possible to follow the 

 growth of each individual tadpole. Unfortunately, all died 

 within ten days. This may have been partly due to the exces- 

 sively warm weather at the time. Because of the short period 



TABLE II. 



of the experiment, the results are not so striking as one might 

 desire but they point in the same direction as the other experi- 

 ments and are quite significant. Table III. gives the results and 

 needs no further explanation. Table IV. gives the dimensions 

 of Bufo tadpoles deprived of both thyroid and pituitary glands 

 but maintained under normal food conditions. A comparison 

 of the tables shows that these do not have hind legs of length at 

 all comparable with those that were fed iodine, even though the 



