342 MAN --AN ADAPTIVE MECHANISM 



Einthoven string galvanometer. If we postulate that 

 a nerve current can pass from the brain to the muscles 

 and glands only if there be a certain difference in 

 potential between these parts, the absence of a nerve 

 current in anesthetized animals may be explained 

 on the basis that any change in the normal alkalinity 

 of the body would diminish the difference in potential ; 

 and hence the acidity produced by inhalation anes- 

 thetics would so far decrease the difference in potential 

 as to inhibit the passage of the nerve impulse. 



According to this hypothesis, as long as life exists, a 

 string galvanometer of sufficient delicacy should detect 

 a nerve current between the brain and the muscles and 

 glands, that is, until the acidity is sufficiently increased 

 to reduce the difference in potential to zero or the 

 death point. During sleep one would expect a dimin- 

 ished flow of action currents. Blood taken from a 

 sleeping man showed normal H-ion concentration. 

 The histologic changes in the brain, the adrenals and 

 the liver, produced by acid sodium phosphate appar- 

 ently, are not repaired during rest without sleep, but 

 are repaired during sleep. 



Acidosis, therefore, may be caused by an intake of 

 a smaller amount of alkalies and bases than are re- 

 quired to maintain an alkaline or neutral state ; by an 

 excessive rate of acid production; or by interference 

 with one or more of the organs of acid elimination. 



This conception of the relation of acidity to anes- 

 thesia and unconsciousness harmonizes many facts. 

 It explains, for instance, how asphyxia, overwhelming 

 emotion or excessive muscular activity, by causing 

 acidity, may produce unconsciousness. It explains 



