Darwin s Theories. 173 



This leads us to a review of Darwin's theories, 

 which were, as we have seen, the result of years of 

 thought and research, and which have conquered or 

 won nearly the entire scientific world of thought. 

 We have seen that his observations in South Amer- 

 ica and elsewhere created the germ which itself, by 

 a series of evolutions, assumed the well-defined 

 and philosophical form of the theory of Darwin of 

 to-day. 



The evolutionists taught that the various species 

 were the simple result of an unfolding, a develop- 

 ment, a growth with constant occurring change ; 

 but they did not tell us how the change was created. 

 Darwin did, and this is how he accomplished it . 

 Probably every reader of this work has, at some time 

 in his life, been the owner of pets rabbits, dogs, or 

 cats, and has from experience obtained certain well- 

 defined ideas of the results which can be produced 

 by careful breeding and intelligent selection. It is 

 known that the race-horse is one result of carefully 

 selecting horses generation after generation which 

 have shown similar characteristics. Trotters with a 

 record are mated ; so with running horses, those 

 adapted for the carriage, or the plough, and the 

 result is existing varieties of the domestic horse. 

 Man began with the original blue-rock pigeon, 

 and has produced all the famous varieties the 

 tumblers, pouters, carriers, and others, this being 

 accomplished by careful and intelligent selection. 

 In dogs, the original companion of early man was 

 a wild animal allied to the wolf. To produce the 

 many varieties (which some naturalists call species), 



