A SUGGESTION AS TO THE EFFECT OF THYROID 



GLAND SUBSTANCES ON PROTOPLASM 



IN GENERAL. 1 



ROBERT A. BUDIXGTOX. 



11 thi numerous angles from which the physiology of the 

 thyroid -land has been approached, that of its influence during 



bryological development has been frequently studied. It i> 

 quite unnecessary for the purposes of the present paper to review 

 the large literature of the subject; bibliographies are abundant. 

 lirielly, one may recall that the effect of administering thyroid 

 material to children is well known; Gudernatsch ('12), followed 

 by many others, showed the precocious differentiation \\hitli 

 follows the feeding of thyroid gland to tadpoles of Amphibia; 

 Knnkel ('18) noted the response of flesh-fly larva- to th\roid 

 ling; its influence on other phyla of animals has been iiuesti- 

 gated, even the Protozoa having been shown to react with an 

 accelerated rate of metabolism, many structural modifications, 

 a taster rate of reproduction, etc., to a thyroid diet. 



In all instances of experimental research the reacting substance 

 i>, of course, protoplasm. Its condition, highly organized into 

 the \aiioas specialized tissues, studied, experimented upon, and 

 interpreted en masse these facts, and our habits of thought, too 

 'hen K-ad us into temporary forgetfulness of protoplasm as the 

 fundamental and only vital substance in the material bein;^ 

 studied. 



A> intimated above, it would seem that so many animals from 

 Mn h distinct levels of organization have shown clear responses to 

 absorbed thyroid materials that we may easily conclude that 

 something in thyroid composition affects and modifies animal 

 protoplasm perhaps whenever and wherever it occurs. Corre- 

 lated with this semihypothetical conclusion, one reflects that 



1 l-ioin tli,- 1 ), paitincnt of Zoology. Oberlin College. The writer wishes to 

 r\l'i,--~ .ippir, i.iii'in "i I, i! '"i atory accommodations and numerous courtesies shown 

 by the Depart iiu -in < :y at Columbia University during tin- latter part of this 



im <n. 



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