LIVING THINGS AND MACHINES 197 



by their construction, so that they cannot 

 alter independently of one another, the living 

 organism can alter its structure and at the 

 same time set aside bye-products without in 

 any way interfering with its own existence or 

 work. In the free play of powers to be met 

 within the living organism lies a profound 

 difference between it and the limited capa- 

 bilities of the machine. Such, in paraphrase, 

 are the views of the distinguished German bio- 

 logist, and the differences on which he insists, 

 one would have thought, would have been such 

 as would have appealed to most observers. 

 Such, however, is not the case, as we may 

 easily see by referring to the books of those Mechanical 



who uphold the mechanical theory and how ex P lana- 



tions 



difficult it is to justify that theory may per- 

 haps be best seen by studying the explanations 

 of their views which have been given by some 

 of the most distinguished amongst them. 



Let us examine a few instances. Herbert 

 g^encer * declines to admit the existence of 

 a nisus formativus or vital force or principle, 

 and is confronted with the necessity of account- 

 ing for the phenomena which he sees before 

 him. How does he do it? He tells us that 

 " the polarities of the molecules determine the 

 direction in which the power (of environing 



* See Principles of Biology, vol. i., App. D., p. 705. 



