14 K. G. HOSKINS 



which our knowledge is most extensive, doubt is entertained by such 

 able physiologists as Gley and Carlson that epinephrin exercises a true 

 hormone function. The possibility remains open that this substance, 

 which may be demonstrated in the gland and which under artificial con- 

 ditions can be demonstrated in the efferent blood vessels, is merely an 

 intermediary product of metabolism that under normal conditions epi- 

 nephrin is not discharged as such at all, but is further elaborated into an 

 inert body before it reaches the blood stream. A clcse analogy to this 

 assumed condition exists in case of urea, which is a harmless end product 

 of potentially harmful nitrogenous metabolites, formed, in part at least, 

 in the liver and discharged via the blood stream through the kidneys. 



Methods by Which Endocrin Functions Are Mediated 



In the present state of our knowledge an adequate discussion of the 

 methods by which the emlocrin glands produce their effects is impossible. 

 Indeed, the very term endocrin, as applied to more than one gland, may be 

 entirely a misnomer. We are wont to assume that any organ which pro- 

 duces effects at a distance without the intervention of the nervous system 

 does so by contributing a specific substance to the circulating medium. 

 But in various instances, as previously stated, the effects may equally well 

 ho explained by an assumption that active substances are removed from the 

 blood and converted into inactive forms as, for example, ammonium salts 

 are converted to urea. Since the discovery of the potency of certain gland 

 extracts, this possibility has largely been ignored. It may well be that 

 future researches will show it to be deserving of more consideration. 

 For a long time the most probable function assigned to the "ductless 

 glands" was that of "detoxicating" the blood. The symptoms that arise 

 after the removal of the parathyroid glands suggest a failure of some 

 detoxicating mechanism. As able a physiologist as Luciani believed that 

 the effects of suprarenal extirpation are likewise due to the accumulation 

 of toxins that are normally removed and destroyed by these glands. As 

 against this hypothesis may be urged the fact that from the body of no 

 animal dying after suprarenal extirpation has a definite toxin been 

 isolated. The writer some years since studied at some length the influence 

 of the blood of dogs dying or recently dead of suprarenal failure on cardiac 

 or skeletal muscular function. Xo difference could be detected in the 

 activity of the isolated hearl beating in normal dog's blood from that of a 

 similar preparation in the blood of an animal from which the suprarenal 

 glands had been removed. Similarly it was found that the activity of a 

 stimulated gastrocneinius was equally extensive and prolonged in either 

 sort of blood. These test tissues were selected because of the fact that 

 cardiac and skeletal muscular weakness are the outstanding features 



