THE ADRENAL GLANDS 787 



adrenal glands, or in a female cat, which is usually indifferent to such a 

 method of frightening. Cannon also thinks that many of the other adap- 

 tations which take place in an animal in this condition are associated with 

 the presence of an excess of epinephrine in the blood. The three most im- 

 portant of these are: (1) increased discharge of sugar from the liver 

 into the blood; (2) increased efficiency of muscular contraction; (3) di- 

 minished clotting time of the blood -all of which are adaptations ena- 

 bling the animal either to conquer the source of the fear or to be in a 

 better position to recover from any bodily injury, which he might suffer, 

 involving a loss of blood. 



It has been pointed out by Stewart and Rogoff, 27 however, that there 

 are several serious sources of error in the methods adopted by Cannon 

 in the earlier investigations, particularly the uncertainty as to the ex- 

 act source of the blood collected through the catheter, the chances for 

 pressor substances developing in the shed blood, the unreliability of using 

 only one test object for the detection of epinephrine in blood, (page 

 784) and the unknown rate of blood flow through the adrenal glands 

 during the removal of the blood. These authors, as a matter of fact have 

 not been able to secure any results which would confirm Cannon's con- 

 clusions, either by repetition of the catheter method employed by this 

 worker, or in other observations in which blood was collected from a 

 pocket of vena'cava (page 784) or in which the pupillary reaction was 

 employed. Neither could Stewart 28 and Rogoff obtain any evidence that 

 an increased secretion of epinephrine bears any relationship to the hyper- 

 glycemia that is induced by ether or by asphyxia. They did not find that 

 animals in which the adrenal had been excised on one side and the nerve 

 supply of the remaining gland cut, responded to emotional conditions in 

 any way differing from normal animals. 



These criticisms have prompted Cannon 29 to repeat his earlier observa- 

 tions by the use of a method which would not entail the removal of blood, 

 that is, by an autoinjection method. He chose as the test object for ex- 

 cess of epinephrine in the blood, a denervated heart which Levy, 30 Gas- 

 ser 31 and Meek had shown to respond by a quickened beat to extremely 

 small concentrations (for example 0.007 mgm. per kg. of "adrenalin" in- 

 jected intravenously per minute increases the heart rate by as much as 28 

 beats per minute). The denervation of the heart was effected by section 

 of the vagi and removal of the stellate ganglia, and in such animals it was 

 found that stimulation of the sciatic nerve, asphyxia and emotional states 

 caused decided acceleration. It would be rash to venture a final verdict 

 at the present stage of this most interesting controversy, but it appears 

 to the author that Cannon's evidence is very strong, provided it can 

 be proved that the heart is really thoroughly denervated and that sub- 



