THE NERVOUS SYSTEM 165 



Professor Cannon's theory is correct there ought 

 to be more adrenaline in the blood after stimula- 

 tion in the above experiment the stimulation was 

 sensory than before stimulation. His experiment 

 tends to show that such is actually the case. 



In a similar manner Cannon has shown that 

 asphyxia "causes a change in the blood producing 

 the same effect as adrenaline on the beating in- 

 testinal strip, namely, inhibition" ; and that emo- 

 tional excitement gives rise to a similar phenome- 

 non. Hence the conclusion that stimulation of the 

 type described whether sensory,! as in pain, 

 whether of the nature of emotional excitement, or 

 of the nature of asphyxia increases the secretion 

 of adrenaline. 



Stewart and Rogoff's criticism. As we shall 

 again refer to Professor Stewart's work, we need 

 only mention here one or two points that bear 

 directly on the technique employed. In a critical 

 review of Cannon's catheter method, Stewart and 

 Kogoff point out that the results obtained by it are 

 only valid if the blood flow is assumed to be con- 

 stant during the whole experimental period, and 

 the method does not permit any judgment on that 

 point. If in the course of an experiment the rate 

 of blood flow over a particular region varies, then 

 the samples taken at various intervals are not 

 strictly comparable. They maintain that the secre- 

 tion of adrenaline is not influenced by reflex stimu- 



