58 FIELDING H. GARRISON 



Beyond this general theory, which is identical with Bordeu's, no special 

 function could be assigned to the different ductless glands. Even Henle 

 asserted that these glands have no influence whatever upon animal life, 

 that they can be extirpated or undergo pathological degeneration without 

 affecting either the sensory or motor functions of the body. The path 

 breaking importance of Addison's great monograph on the effect of disease 

 of the suprarenal capsules may be thrown into relief by citing Hyrtl's 

 witticism about the suprarenal that the unknown nature of its functions 

 insures it from bothersome investigation at the hands of medical men 

 ("Die unbekannte Function der Nelenniere sichert dieses Organ von 

 lastigen Nachfragen in der Heilwissenschafl"). 



If we regard the lungs or the individual cells of the body tissues pro- 

 visionally as ductless glands, then it will be perceived that .the truth of the 

 equation formulated by Legallois had already been demonstrated quanti- 

 tatively when Lavoisier proved that inspired air is converted into carbon 

 dioxid and water, and when Lagrange, through his pupil Hassenfratz, 

 proved that the oxygen in inspired air, being dissolved in the blood, takes 

 up carbon and hydrogen from the body tissues as the blood courses through 

 them (1791). AVe now know that the respiratory center in the medulla is 

 stimulated by the C(X in the venous blood, which Lavoisier and Lagrange 

 had shown to be, in effect, a true metabolite, or waste product of tissue 

 oxidation. Their work was, in fact, the starting point of the chemical 

 study of metabolism, which received its next great advancement in Claude 

 Bernard's study of glycogen ; for, although the latter may not be, in the 

 strict sense, a true internal secretion, discharged from a gland into the 

 blood, yet its investigation led Bernard (d) to the classical statement of the 

 doctrine of internal secretions as such : 



"In animals the glycogenic secretion is an internal secretion because it is dis- 

 charged directly into the blood. I have considered the liver, as found in the higher 

 vertebrates, as an organ with a double secretory function. It seems to reunite, in 

 effect, two distinct secretory elements, and it represents two secretions, one external, 

 the biliary secretion, the other internal, the glycogenic secretion, which is discharged 

 into the blood." 



In the year 1843 Claude Bernard, in his graduating thesis, made the 

 discovery that cane sugar is acted upon by the gastric juice, being converted 

 by it into dextrose. This experimental fact led to a train of reasoning, 

 which was to revolutionize the physiology of nutrition and metabolism and 

 at the same time to introduce the new concept of internal secretions, and to 

 be the startinc; point of the experimental production of disease by the arti- 

 ficial uso of chemical and physical agencies. All carbohydrates, Bernard 

 reasoned, must get into the blood in the form of dextrose. "What becomes 

 of this dextrose?" he next inquired. Somewhere between the alimentary 

 canal (vi<i the portal vein) and the liver, between the liver (via the right 

 heart ) and the lungs, between the lungs (via the left heart) and the various 

 body tissues, this dextrose is either destroyed and disappears or is trans- 



