140 LIFE IN NATURE. 



the entire advance of physiological knowledge since 

 his day. 



His idea (derived, it is said, originally from 

 Schelling) is, that physical life is a process, or a 

 mode of operation, of the same powers which we 

 recognize under other names, as magnetism, elec- 

 tricity, or chemical affinity. These, by their own 

 properties, effect all the results observed in life, 

 but they are grouped in a special way, the various 

 forms of action being so united as to constitute, out 

 of many parts, a mutually dependent whole. The 

 distinctive character of living things is the exhibition 

 in them of a "principle of individuation," which con- 

 stitutes them units, separated from, while yet par- 

 takers in, that which is around them. "Life," he 

 says, " supposes an universal principle in nature 

 with a limiting power in every particular animal, 

 constantly acting to individualize, and, as it were, 

 figure the former. Thus, life is not a thing, but an 

 act and process." And tracing the chain of organic 

 being upward through its various grades, he points 

 out how the great characteristic of advancing eleva- 

 tion in the scale of life, consists in the ever more 



