author's abstract of this paper issued by 

 the bibliographic service, november 24 



THE RESULTS OF THYROID REMOVAL IN THE 

 LARVAE OF RANA PIPIENS 



r 



. BENNET M. ALLEN 



Zoological Laboratory, University of Kansas 



EIGHT TEXT FIGURES AND ONE PLATE 



There have been many experiments upon the effects of removal 

 of the thyroid gland in the adults and young of mammals. 

 Much has been learned regarding its effect upon metabolism and 

 upon growth and we have multitudinous clinical data upon thy- 

 roid insufficiency; but up to the present time there have been no 

 accounts of the effects of the development of animals from which 

 the thyroid gland has been removed at the very beginning of its 

 development. It is obviously extremely difficult to accomplish 

 this operation in the early embryonic stages of reptiles and 

 birds, while in the mammals such an operation would appear to 

 be well nigh impossible. Because of these difficulties of tech- 

 nique we must turn to the amphibians for such experiments. 



The work of Gudernatsch ( r 12 and '14) many times verified by 

 others showed clearly that thyroid feeding (giving an excess of 

 thyroid secretion) greatly accelerates the differentiation — meta- 

 morphosis of tadpoles, causing that process to take place very 

 precociously thus producing absurdly small frogs with all four 

 limbs, with no tail, with the frog type of head and with an ali- 

 mentary tract greatly reduced in length as compared with con- 

 trols of the same age. 



The writer thought that the complete extirpation of the thy- 

 roid gland might give equally striking evidence of the influence 

 exerted by that gland upon development. This hypothesis was 

 most thoroughly vindicated by the results of these experiments. 

 This account will deal with the general effects upon the body as 

 a whole and in a more special way with the effects upon the 



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