THYROID REMOVAL IN LARVAE OF RANA PIPIENS 



509 



TABLE 3 



Males 



DATE KILLED 



ESTIMATED 

 VOLUME 



Controls 



Thyroidless 



Starved Control 



MS 



February 22 



27 



66 



R.0.64 



L.0.57 



0.27 

 0.35 



0.23 

 0.26 



0.0419 

 0.0581 



very many sperm are present. It is thus clearly demonstrated 

 that spermatogenesis proceeds normally and sexual maturity is 

 attained in thyroidless tadpoles that have retained larval char- 

 acteristics long after the time for metamorphosis. This is in 

 sharp contrast to the fact that even in the completely meta- 

 morphosed frogs killed in July and August, there is no sign of 

 spermatogenesis. 



THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 24, NO. 3 



