THE SYMPATHETIC SYSTEM 13 



trition. These substances of glandular origin, having 

 a specific stimulating action have been called functional 

 stimulants and were termed hormones by Starling in 1905. 

 It is by the intermediary of these hormones that the 

 functional corollation of chemical origin which was sus- 

 pected by Claude Bernard, is accomplished, as dif- 

 ferentiated from corollation of nervous origin, which has 

 been known for a long time. But simply to know of the 

 existence of hormones does not mean that we understand 

 them well. The duodenal secretin stimulating the pan- 

 creas is a certain type of hormone, the suprarenalin, a 

 product of the chromaffin cells of the suprarenals and 

 other cells, has a stimulating act on the cardio vascular 

 system and represent another type of hormone. It is also 

 possible that iodothyrin really exists, although not isolated 

 definitely and that it may have a stimulating metabolic 

 effect on connective tissue. It is possible that there are 

 other hormones of endocrin origin, but so far we know 

 very little about them. 



Next to hormones, the endocrine glands secrete sub- 

 stances which are not cellular stimulants but materials 

 which they utilize. Glycogen of hepatic origin, the fats, 

 are examples of nutritive substances utilized in the forma- 

 tion of energy. Other substances must be used in the 

 repair of the blood (specific proteins of the blood). 

 Outside of these, those which are of most interest to the 

 physician are those which help in the building up of 

 tissues during the course of development of the organism; 

 these are the morphogenetic substances. Physiology, anat- 

 omy and clinical experience have shown the evidence of 

 glands having a morphogenic action, such as, the inter- 

 stitial gland of the testicle, the corpus luteum, the thy- 

 roid, the pituitary. The substances secreted by these 

 glands have a chemical morphological action, the study 



