PERPETUATION OF LIVING BEIXGS. 115 



make out that there are many species of it, and others 

 maintaining that they are but many varieties of one 

 species ; and they cannot settle to this day which is a 

 species and which is a variety ! 



So that there can be no douht whatsoever that any 

 plant and any animal may vary in nature ; that varie- 

 ties may arise in the way I have described, — as sponta- 

 neous varieties, — and that those varieties may be per- 

 petuated in the same way that I have shown you 

 spontaneous varieties are perpetuated ; I say, therefore, 

 that there can be no doubt as to the origin and per- 

 petuation of varieties in nature. 



But the question now is: — Does selection take place 

 in nature? is there anything like the operation of man 

 in exercising selective breeding, taking place in nature '{ 

 You will observe that, at present, I say nothing about 

 species; I wish to confine myself to the consideration 

 of the production of those natural races which every- 

 body admits to exist. The question is, whether in na- 

 ture there are causes competent to produce races, just 

 in the same way as man is able to produce, by selec- 

 tion, such races of animals as we have already noticed. 



When a variety has arisen, the Conditions of Exist- 

 ence are such as to exercise an influence which is 

 exactly comparable to that of artificial selection. By 

 Conditions of Existence I mean two things, — there are 

 conditions which are furnished by the physical, the in- 

 organic world, and there are conditions of existence 

 which are furnished by the organic world. There is, 

 in the first place, Climate ; under that head I in- 

 clude only temperature and the varied amount of 

 moisture of particular places. In the next place 

 there is what is technically called Station, which 



