FEEDING THYMUS TO FROG LARV.E. 



119 



A second series of larvae, one hundred in number and averaging 

 10 mm. in length, were selected and treated the same as the series 

 above. Fifty larvae were for thymus feeding and fifty for control 

 purposes. These larvae were from a batch of eggs gathered a few 

 days later than the larvae of the first series. Hence, throughout 

 the following experiment, the series averaging nearly 13 mm. in 

 length when started upon the thymus feeding I shall designate 

 as Thymus No. I, the series averaging 10 mm., at the beginning 

 of the work, as Thymus No. 2. 



TABLE I. 



APRIL 12. 

 Length. 



The experimental larvae of both series were each day fed 

 finely shredded bits of the fresh thymus glands of calves 3-12 

 months of age. Only the glands of young animals were used. 

 The glands were obtained from a nearby slaughter-house, and 

 extirpated by myself. 



The control animals were fed fresh beef liver each day. Care 

 was taken to give as nearly as possible the same amount of 

 protein material to the animals in each container and of each 



