276 CRILE— THE KINETIC SYSTEM. [April 22. 



histological changes characteristic of exhaustion. Alkalies cause 

 suprarenal changes, but acids do not. 



We have shown that brain and suprarenal activity go hand in 

 hand^that is, that the suprarenal secretion activates the brain, and 

 that the brain activates the suprarenals. The fundamental question 

 which now arises is this : Are the brain and the suprarenals inter- 

 dependent? A positive answer may be given to this question, for 

 the evidence of the dependence of the brain upon the suprarenals is 

 as clear as is the evidence of the dependence of the suprarenals upon 

 the brain, (i) After excision of the suprarenals, the brain-cells 

 undergo continuous histological and functional deterioration until 

 death. During this time the brain progressively loses its power to 

 respond to stimuli and there is also a progressive loss of muscular 

 power and a diminution of body temperature. (2) In our crossed 

 circulation experiments we found that adrenalin alone could cause 

 increased brain activity, while histologically we know that adrenalin 

 alone causes an increase of the Nissl substance. An animal both of 

 whose suprarenals had been excised showed no hyperchromatism in 

 the brain-cells after the injection of strychnin, of toxins, of foreign 

 proteins, etc. (3) When the suprarenal nerve supply was divided 

 (Cannon-Elliott), then there was no increased suprarenal activity in 

 response to adequate stimuli. 



From these studies we are forced to conclude not only that the 

 brain and suprarenals are interdependent, but that the brain is ac- 

 tually more dependent upon the suprarenals than the suprarenals 

 upon the brain, since the brain deteriorates progressively to death 

 without the suprarenals, while the suprarenals whose connection with 

 the brain has been broken by the division of their nerve supply will 

 still produce sufficient adrenalin to support life. 



From the strong affinity of the brain-cells for adrenalin which 

 was manifested in our experiments, we may strongly suspect that 

 the Nissl substance is a volatile, extremely unstable combination of 

 certain elements of the brain-cells and adrenalin because the supra- 

 renal glands alone do not take the Nissl stain and the brain deprived 

 of adrenalin does not take Nissl stain. The consumption of the Nissl 

 substance in the brain-cells is lessened or prevented by morphin as is 

 the output of adrenalin ; and the consumption of the Nissl substance 



