46 DARWINISM AND HUMAN LIFE 



organs. It is of the very nature of an organism that 

 there should be mutual dependence among its parts. 

 The organs are all partners in the business of life, 

 and if one member changes others also are affected. 

 This is especially true of certain organs that have 

 developed and evolved together, and are knit by 

 close physiological bonds. We know in health 

 how nerve and muscle, brain and sense-organs, 

 heart and lungs, are closely bound together in the 

 bundle of life. We know in disease that a change 

 in one organ often affects another, and the fact 

 remains, though the nexus is sometimes mysterious. 

 The state of our liver may give colour to our whole 

 intellectual firmament, and a slight ocular de- 

 rangement may warp a wise man's philosophy. 

 The far-reaching importance of a little organ like 

 the thyroid gland beside the larynx is well known ; 

 our intellectual as well as our bodily health de- 

 pends on its soundness. Now, just as there is 

 a correlation of organs within the body, so there 

 is a correlation of organisms in that system of 

 things which we call Nature. In both cases we 

 are here using the word " correlation " in its deeper 

 sense that the various parts are more than 

 mutually dependent, that they are in some measure 

 co-ordinated, making larger systems workable. 



WHAT THE METAPHOR OP " THE WEB OF LIFE " 

 SUGGESTS. We may use the metaphor " web of 

 life " in two ways. On the one hand, Nature has a 

 woven pattern which science seeks to read, each 

 science following the threads of a particular colour. 

 There is a warp and woof in this web, which to the 

 zoologist usually appear as " hunger " and " love/' 

 There is a changing pattern in the web, becoming 

 more complex as the ages pass ; and this is evo- 



