DEFINITION OF THE TERM ' INTERNAL SECRETION ' 5 



interchange between the cells of different organs, and this 

 functional interdependence he designated "cell-altruism." As 

 the founder of the doctrine of internal secretion, Brown-S^quard 

 has opened to physiology a new and fruitful field for experiment ; 

 he has paved the way for the right understanding of many 

 pathological derangements ; and he has pointed out a rational and, 

 in many cases, a remarkably successful method of treatment. 



DEFINITION AND LIMITATION OF THE TERM 

 -INTERNAL SECRETION/' 



Two agents are concerned in ordering and maintaining the 

 complex activity of the animal organism. In addition to the 

 nervous intercommunication, which is admittedly the agent in 

 effecting rapid adjustments, there is also a chemical correlation 

 of the different organs. In accordance with the latter, each 

 organ, each tissue, and even each cell, by means of its specific 

 secretory products, acting through the agency of the blood-stream, 

 is enabled to exert a definite influence upon other parts of the 

 body. In this manner the equilibrium of the various parts is 

 guaranteed. 



It must not be imagined, however, that chemical communi- 

 cation is effected by the agency of the blood-stream only. We 

 know, for instance, that the acid secretion which is elaborated 

 upon the superficial membrane of the stomach, causes the pyloric 

 sphincter to relax at regular intervals, and that movements of the 

 intestinal canal are provoked by the bowel-contents. Granting 

 that in these instances there is also a nervous reflex w r hich is 

 set in motion by the secretions of the gastric and intestinal mucosa, 

 yet the formation of secretin is clearly an instance of chemical 

 interaction taking place upon an internal surface. 



As soon as it enters the duodenum, the acid gastric secretion 

 (then called chyme) excites the cells of the intestinal mucosa 

 to form secretin, which, in its turn, acting through the blood- 

 stream, stimulates the liver to an increased production of bile, 

 excites the formation of pancreatic secretion, and promotes 

 secretion by the glands of the intestinal walls. Bayliss and 

 Starling, who have made a special study of these processes, 

 propose that the name " hormone ' should be given to those 

 physiological substances which act as chemical stimuli and serve 

 as intermediaries between different parts of the body. 

 " Hormone ' is derived from the Greek op/.idw, meaning to 

 awake or excite, and the term has been universally adopted. 



All organs which supply substances which are capable of 

 exciting or in any way of affecting the functions of other organs, 

 may be described as " hormone-producing." Schiefferdecker 

 proposes that they should be called " Beeinflussungsorgane ' 



