INFLUENCE OF ENVIRONMENT 127 



could no longer survive, and the possibility of finding other localities 

 and transporting themselves thither would not be open to them. 



The second conclusion is my own : it assumes that by the influence 

 of environment on habit, and thereafter by that of habit on the state of 

 the parts and even on organisation, the structure and organisation 

 of any animal may undergo modifications, possibly very great, and 

 capable of accounting for the actual condition in which all animals 

 are found. 



In order to show that this second conclusion is baseless, it must 

 first be proved that no point on the surface of the earth ever under- 

 goes variation as to its nature, exposure, high or low situation, climate, 

 etc., etc. ; it must then be proved that no part of animals undergoes 

 even after long periods of time any modification due to a change of 

 environment or to the necessity which forces them into a different 

 kind of life and activity from what has been customary to them. 



Now if a single case is sufficient to prove that an animal which has 

 long been in domestication differs from the wild species whence it 

 sprang, and if in any such domesticated species, great differences 

 of conformation are found between the individuals exposed to such a 

 habit and those which are forced into different habits, it will then be 

 certain that the first conclusion is not consistent with the laws of 

 nature, while the second, on the contrary, is entirely in accordance 

 with them. 



Everything then combines to prove my statement, namely : that 

 it is not the shape either of the body or its parts which gives rise to 

 the habits of animals and their mode of life ; but that it is, on the con- 

 trary, the habits, mode of life and all the other influences of the environ- 

 ment which have in course of time built up the shape of the body and 

 of the parts of animals. With new shapes, new faculties have been 

 acquired, and little by Httle nature has succeeded in fashioning animals 

 such as we actually see them. 



Can there be any more important conclusion in the range of natural 

 history, or any to which more attention should be paid than that 

 which I have just set forth ? 



Let us conclude this Part I. with the principles and exposition of 

 the natural order of animals. 



