CHAPTER XV 



THE BACKGROUND OF DARWINISM— Continued 



THE WEB OF LIFE^ 



J. ARTHUR THOMSON 



Naturalists, in the true sense, who study the life of living creatures 

 in nature, have always been distinguished by a keen perception of the 

 interrelations of things. Whether we take Gilbert White as repre- 

 senting the old school, or W. H. Hudson as representing the new, we 

 get from their observations the same impression of nature as a vibrat- 

 ing system, most surely and subtly interconnected. But it seems 

 just to say that no naturalist, before or since, has come near Darwin 

 in his realisation of the web of life, in his clear vision and picture of the 

 vast system of linkages that penetrates throughout the animated 

 world. 



Correlation of organisms as well as correlation of organs. — In 

 thinking of a living body we are accustomed to the idea of the cor- 

 relation of 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 myste- 

 rious. The state of our liver may give colour to our whole intellectual 

 firmament, and a slight ocular derangement 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 depends 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 — 



^ From J. A. Thomson, Darwinism and Human Life (copyright 1909). Used 

 by special permission of the publishers, Henry Holt & Company. 



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