CHAPTER VII* 



LIFE 



ALL forces are known by the phenomena which they 

 cause. So long as the animal and plant were supposed 

 to exist in opposition to ordinary physical forces or inde- 

 pendently of them, a vital force or principle was postu- 

 lated by which the work of the body was performed. 

 It is now known that most, if not all, of the phenomena 

 manifested by a living body are due to one or more of 

 the ordinary physical forces, heat, chemical affinity, 

 electricity, etc. There is no work done which demands 

 a vital force. 



The common modern view is that vitality is simply a 

 collective name for the sum of the phenomena displayed 

 by living beings. It is neither a force nor a thing at 

 all, but is an abstraction, like goodness or sweetness ; 

 or, to use Huxley's expression, to speak of vitality is as 

 if one should speak of the horologity of a clock, mean- 

 ing its time-keeping properties. 



A third theory is still possible. The combination of 

 elements into organic cells, the arrangement of these 

 cells into tissues, the grouping of these tissues into 

 organs, and the marshaling of these organs into plans 

 of structure, call for some further shaping, controlling 

 power to effect such wonderful coordination. More- 

 over, the manifestation of feeling and consciousness is a 

 mystery which no physical hypothesis has cleared up. 

 The simplest vital phenomenon has in it something over 



* See Appendix. 

 DODGE'S GEN. ZOOL. 15 225 



