92 MEDULLA 



this blood must contain a substance which inhibits the normal 

 epinephrine effect on the denervated pupil. 



Kojima and Saito 360 also found that the intestinal segment 

 method gave results which were higher for epinephrine than the 

 colorimetric method of Folin, Cannon, and Denis. 



9. Denervated heart method. In their earlier experiments 

 Cannon and Hoskins 105 obtained blood from the adrenal vein 

 by means of a catheter passed through the femoral artery and 

 pushed forward until it reached a point near the entrance of the 

 adrenal vein into the vena cava. The blood obtained was 

 assayed by the intestinal segment method. This method of 

 Cannon and Hoskins although applicable to the unanesthetized 

 animal suffers from the fact that it cannot give quantitative 

 results and was therefore discarded for an auto-assay method 

 depending on the use of the denervated heart. 



Cannon and his collaborators 102 have utilized the denervated 

 heart as a sensitive test object for the assay of epinephrine. 

 This preparation is prepared by severing all the nervous con- 

 nections of the heart. After recovery from the operation, the 

 heart rate is considered by Cannon to be under hormonal con- 

 trol and to react only to changes in the blood concentration 

 of epinephrine or related substances. 



Stewart and Rogoff 587 criticized the method of Cannon on the 

 basis of their experiments in which they showed that an increase 

 in the rate of the denervated heart may be elicited even after 

 extirpation of the adrenals. 



Cannon and Rapport, 102 using the denervated heart as an 

 indicator, found that stimulation of the splanchnics caused an 

 increase of 29 beats in the pulse rate. After removal of the 

 adrenals the increase was only 6 beats and they concluded, 

 therefore, that the difference was caused by secretion of epi- 

 nephrine in response to splanchnic stimulation. The increase 

 noted after adrenalectomy was attributed to the liver, for 

 section of the hepatic nerves abolished this increase. Since 

 removal of the adrenals caused a slowing of the pulse rate 



