FEEDING THYMUS TO FROG 



123 



TABLE IV. 



MAY 4. 



Length. 



larvae possessed hind limb buds; these were plainly visible 

 without the aid of a hand lens. The larvae of both groups of 

 animals had increased in size considerably but the average length 

 of the larvae of each group varied but little, and such variations 

 are negligible. This is clearly indicated in Table V. 



OBSERVATIONS OF MAY 13. 



When examined the larvae of both control and thymus-fed 

 groups had increased in length considerably. All of the tadpoles 

 of both groups had developed hind limb buds and most of the 

 limb buds of the thymus-fed larvae had differentiated into their 

 two primary divisions and had developed the toe points. The 

 controls seemed somewhat behind the thymus-fed larvae in 

 respect to the length of the limbs. The pigmentation of the 

 experimental animals was darker than the liver-fed controls. 



In other respects the larvae of the two groups appeared the 

 same. Table VI indicates that the larvae of all groups averaged 

 nearly the same length. The differences are negligible. 



