184 W. B. CANNON 



as has been repeatedly noted (Lewandowsky(c), Camus and Langlois, Hos- 

 kins and Wheelon), removal of both suprarenals does not for some time 

 cause the fall of arterial pressure which naturally would be expected if 

 continued secretion of epinephrin were needed to keep the pressure up; 

 and also stimulation of the splanchnic nerves induces the same rise of pres- 

 sure after suprarenal excision as before (Gley and Quinquaud(e), 1918). 

 From these results the conclusion has been drawn by Hoskins and McClure 

 and by Gley and Quinquaud that the tonus theory is without adequate 

 experimental support. 



The emergency theory was presented by Cannon (a) (1914) on the basis 

 of studies of suprarenal secretion following stimulation of afferent nerves, 

 asphyxia and emotional excitement. In the papers bearing upon this 

 theory emphasis was repeatedly laid upon the association between supra- 

 renal activity and the activity of the sympathetic division of the autonomic 

 system in such emergencies. Nowhere has the statement been made that 

 secreted epinephrin has a function separate from that of the nerve impulses, 

 except to increase the irritability of fatigued muscles (Cannon and Nice; 

 Gruber(d)) and to speed the coagulation of the blood (Cannon and Men- 

 denhall). The idea originally suggesting these studies on suprarenal secre- 

 tion was that changes in the viscera originally induced by nervous impulses 

 might be continued by circulating epinephrin (Cannon(&), 1915). No 

 claim has ever been made that there is at any stage a primacy of epinephrin 

 in the production of physiological or psychological changes seen during 

 strong emotion. 



Thus far no reliable evidence has been brought out by any investigator 

 that there is any secretion of the suprarenal glands under quiet, peace- 

 ful conditions. Stewart and Rogoff have shown that the cat and the dog 

 Avill live normally for weeks with one adrenal excised and the other de- 

 nervated, an operation which may result in no demonstrable flow of 

 epinephrin from the suprarenal vein (19lT(e) ). These observations prove 

 that suprarenal secretion is not a necessity, at least in times of serene 

 existence. There is evidence, however, that epinephrin is secreted in 

 times of great emotional stress and under circumstances which cause pain 

 or asphyxia. The function of the suprarenal medulla is to be looked for 

 under conditions which rouse it to action. Excitement, pain and asphyxia 

 are, in natural existence, commonly associated with violent struggle for 

 self-preservation. Under such circumstances, as has been emphasized in 

 the presentation of the emergency theory, the operation of the sympathetic 

 division of the autonomic system together with the aid which epinephrin 

 affords will muster the resources of the organism in such a way as to be of 

 greatest service to such organs as are absolutely essential for combat, 

 night or pursuit. The cessation of activities of the alimentary canal; the 

 shifting of the blood from the less insistent abdominal viscera to the 

 organs immediately essential to life itself, such as the lungs, the heart, 



