EXPERIMENTS WITH FEEDING THYMUS GLANDS 



TO FROG 



W. W. SWINGLE, 

 DEPT. ZOOLOGY, UNIVERSITY OF KANSAS. 



INTRODUCTION. 



In 1912, J. F. Gudernatsch published an account of his 

 investigation concerning the effects of feeding various glands of 

 internal secretion to frog larvae. Among other interesting results 

 observed, was the significant one, that fresh thymus gland, when 

 fed to tadpoles, stimulates the growth processes of these animals 

 and at the same time inhibits the onset of metamorphosis. 



In a later communication, January, 1914, this author repeated 

 his previous experiments with thymus feeding, and confirmed 

 his earlier results. For an understanding of the relation between 

 growth and the secretory products of the thymus gland, the 

 importance of the results obtained by this investigator warranted 

 a repetition of his work, which, so far as the writer is aware, has 

 never been questioned. It was with this end in view that the 

 following experiment was undertaken. 



LITERATURE. 



The experimental researches upon the thymus gland may 

 roughly be divided into two groups: those dealing with the 

 relation between the thymus and bodily growth, and those 

 concerned with the correlation in function of the thymus and 

 sex glands. The literature dealing with the former problem is 

 more extensive than that concerned with the latter. 



EFFECTS OF EXTIRPATION UPON GROWTH. 



One of the first investigators of this problem was Carbone; 

 this experimenter extirpated the thymus of rabbits, and one 

 dog, and found that the animals did not differ in their develop- 

 ment from control animals of the same litter. 



Another investigator, Ghika, removed the thymus from eight 



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