The Origin of Organic Forms. 193 



organic evolution is thereby made of none effect ; for, 

 within the ken of science, it is reduced to a merely 

 phenomenal succession of forms, without a causal 

 nexus binding them to one another. Instead of the 

 disclosure of a knowable cause, which may be brought 

 into relation with other known causes, the evolutionist 

 sees ignorance wrapped up in an incomprehensible 

 term, or hidden behind a sacred name. 



Mr. Spencer, on the other hand, undertakes to carryj 

 his hypothesis through without taking account of any 

 cause unknown to science. The active causes which 

 he finds operative in the course of organic evolution 

 are : (a) An innate tendency or polarity in the physi-' 

 ological units of which organized bodies are built up ; 

 and (b) the play of the incident forces of the environ- 

 ment. The entire process is explained by these two 

 sets of forces. In what proportions they co-operate 

 in producing all known varieties of living things, Mr. 

 Spencer has not indicated. He deals in a hesitating 

 and tentative way with the whole subject. The sum 

 of his teaching is that the environing forces are the 

 source of the power which effects the changes, the 

 polarity of the units directing it. The doctrine is not 

 by any means expounded with clearness and precision. 

 The following fairly represents it : The physiological 

 unit has its internal structure its equilibration of 

 forces within itself. All other units in the organism 

 form a part of its environment ; while to these groups 

 of units the entire organic structure stands in the 



