CHAPTER VIL 



OF THE INFLUENCE OF THE ENVIRONMENT ON THE ACTIVITIES 

 AND HABITS OF ANIMALS, AND THE INFLUENCE OF THE 

 ACTIVITIES AND HABITS OF THESE LIVING BODIES IN MODI- 

 FYING THEIR ORGANISATION AND STRUCTURE. 



We are not here concerned with an argument, but with the examina- 

 tion of a positive fact — a fact which is of more general application than 

 is supposed, and which has not received the attention that it deserves, 

 no doubt because it is usually very difficult to recognise. This fact 

 consists in the influence that is exerted by the environment on the 

 various living bodies exposed to it. 



It is indeed long since the influence of the various states of our 

 organisation on our character, inclinations, activities and even ideas 

 has been recognised ; but I do not think that anyone has yet drawn 

 attention to the influence of our activities and habits even on our 

 organisation. Now since these activities and habits depend entirely 

 on the environment in which we are habitually placed, I shall endeavour 

 to show how great is the influence exerted by that environment on the 

 general shape, state of the parts and even organisation of living bodies. 

 It is, then, with this very positive fact that we have to do in the 

 present chapter. 



If we had not had many opportunities of clearly recognising the 

 result of this influence on certain living bodies that we have trans- 

 ported into an environment altogether new and very different from 

 that in which they were previously placed, and if we had not seen 

 the resulting effects and alterations take place almost under our very 

 eyes, the important fact in question would have remained for ever 

 unknown to us. 



The influence of the environment as a matter of fact is in all 

 times and places operative on living bodies ; but what makes this 

 influence difficult to perceive is that its effects only become percep- 

 tible or recognisable (especially in animals) after a long period of time. 



