6S PHYSICAL CHEMISTRY IN MEDICINE. 



far enough to show that it contains all those elements 

 which we discovered in the discussion of another subject. 

 The idea that antagonistic reactions must be possible 

 in even the smallest particles of protoplasm we meet in 

 HERING'S theory of the changes that go on in living matter. 

 In the discussion of assimilation and dissimilation, he 

 writes : 



" But in separating the mental conceptions of these 

 two processes we must not be misled into thinking of 

 them as two processes which, while they go on side by 

 side, are really separated, and into imagining living sul> 

 stance to be within itself a resting mass that on one side 

 only analyzes matter and on the other only synthesizes 

 it ; but rather as a copper wire dipping with both its ends 

 into copper sulphate, which when it is traversed by an 

 electric current suffers at one end a loss of copper by 

 going into solution, while at the other end it has copper 

 deposited upon it. We must rather imagine assimilation 

 and dissimilation as two closely interwoven processes which 

 constitute the still unknown metabolism of living matter, 

 and which take place simultaneously in even the smallest 

 particles of living matter, for living matter represents not 

 something fixed or resting, but something more or less 

 labile." . 



The investigations of HERING on the sensations of 

 light and color led him to the assumption of three kinds 

 of antagonistic processes in the visual substance, corre- 

 sponding with the three pairs of sensations, red-green, 

 yellow-blue, and black-white. The red-green and the 

 yellow-blue reactions each constitute a pair of antagonists 

 which mutually destroy each other, so that only the 

 simultaneous black-white reaction remains. Red and 



