74 EVOLUTION 



mentary canal into the blood-vessels, can be 

 completely described in terms of physical 

 formulse. The fact is that when we add up 

 the components revealed by chemical and 

 physical analysis, they do not amount to 

 the whole resultant which we see in a vital 

 action, even of a simple sort. 



It is indeed profitable to compare a living 

 creature to a machine, and a fertile method 

 of discovery to press this comparison to its 

 hardest. Yet the living organism differs 

 from any machine in its greater efficiency; 

 and especially in this, that the transfer of 

 energy into it is attended with effects con- 

 ducive to further transfer and retardative 

 of dissipation. Again in this, that it is a 

 self-stoking, self-repairing, self-preservative, 

 self-adjusting, self-increasing, self-repro- 

 ducing engine! And this also must be re- 

 membered in comparing a living creature 

 and a machine, that the latter is no ordinary 

 sample of the inorganic world. It is an 

 elaborated tool, an extended hand, and has 

 inside of it a human thought. It is because 

 of these qualities that highly complex ma- 

 chines come to be so like organisms. But 

 no machine profits by experience, nor trades 

 with time as organisms do. Therefore it is 

 that the formulae that serve to describe the 

 activity of a machine will not suffice for 



