126 



W. W. SWINGLE. 



grown so large that it was considered best to avoid handling 

 them, as much as possible. During the eighteen-day interval 

 only four tadpoles died. One was a control and the other 

 three were thymus-fed animals. The four larvae became bubbly, 

 i. e., air vacuoles appeared in the region of the lungs under the 

 skin. The larvae came to the surface and floated on their backs; 

 death usually resulted within a few days. The following table 

 indicates the measurements of the larvae. 



TABLE VIII. 



OBSERVATIONS JUNE 8. 



Measurements of the Larva. 



OBSERVATIONS OF JUNE 8. 



The larvae of both control and thymus-fed cultures had grown 

 considerably in the eighteen-day interval between the observa- 

 tions of May 20 and June 8. All of the tadpoles of both groups 

 possessed well-developed limbs, some measuring n mm. in 

 length. The limbs of the thymus-fed animals averaged in length 

 about the same as the controls; this was true also of body length, 

 as a glance at Table VIII. w r ill show. 



In regard to pigmentation, activity and mortality among the 



