106 MEDULLA 



be increased by thyroid feeding but Kuriyama 369 was unable to 

 confirm this. Gley 223 found that thyroidectomy or pan- 

 createctomy did not affect the epinephrine store of the adrenals. 



THE FUNCTION OF EPINEPHRINE 



Despite the extensive studies which have been carried out on 

 epinephrine, we are still in ignorance of its function in the 

 organism. Many theories have been advanced to explain 

 the functional significance of the adrenal medulla and its 

 secretion, but the validity of most of these theories is easily 

 disproven and none of them will satisfactorily explain all our 

 chemical, physiological, and anatomical knowledge concern- 

 ing the medulla. 



That epinephrine serves an important function in the organ- 

 ism is an assumption which can scarcely be denied when one 

 considers the facts presented in the preceding sections. It 

 would seem most reasonable, therefore, to adopt the view that 

 we are ignorant of the function of epinephrine rather than 

 omnisciently to disclaim any importance for this substance, 

 and consider it as a waste product of the animal economy, as 

 some have done. 



One conclusion is inescapable: viz., that the deprivation in 

 the mammal of the epinephrine store (by adrenalectomy) 

 does not result in any perceptible deficiency. Nor can it be 

 satisfactorily argued that the loss of epinephrine is compensated 

 for by the relatively small stores of epinephrine present in the 

 extra-medullary chromaphil bodies. In the rat, such extra 

 tissue has not been demonstrated and this animal can grow 

 and flourish after adrenalectomy when furnished with an 

 adequate supply of the cortical hormone. That the extra- 

 medullary chromaphil tissue does not replace the normal secre- 

 tion of the medulla is also demonstrated by its failure to hyper- 

 trophy after adrenalectomy. We can thus safely say that the 

 function of epinephrine is dispensable to the organism. 



One of the early theories of the function of epinephrine was 



