172 THE ORIGIN OF SPECIES 



for in the large and well-illustrated work which he is said to 

 be preparing for publication. 



The Darwinian hypothesis has the merit of being eminently 

 simple and comprehensible in principle, and its essential 

 positions may be stated in a very few words : all species 

 have been produced by the development of varieties from 

 common stocks by the conversion of these first into per- 

 manent races and then into new species, by the process of 

 natural selection, which process is essentially identical with 

 that artificial selection by which man has originated the 

 races of domestic animals the struggle for existence taking 

 the place of man, and exerting, in the case of natural 

 selection, that selective action which he performs in artificial 

 selection. 



The evidence brought forward by Mr. Darwin in support 

 of his hypothesis is of three kinds. First, he endeavours to 

 prove that species may be originated by selection ; secondly, 

 he attempts to show that natural causes are competent to 

 exert selection ; and thirdly, he tries to prove that the most 

 remarkable and apparently anomalous phenomena exhibited 

 by the distribution, development, and mutual relations of 

 species, can be shown to be deducible from the general 

 doctrine of their origin, which he propounds, combined with 

 the known facts of geological change ; and that, even if all 

 these phenomena are not at present explicable by it, none 

 are necessarily inconsistent with it. 



There cannot be a doubt that the method of inquiry which 

 Mr. Darwin has adopted is not only rigorously in accordance 

 with the canons of scientific logic, but that it is the only ade- 

 quate method. Critics exclusively trained in classics or in 

 in ;it hem {i tics, who have never determined a scientific fact 

 in their lives by induction from experiment or observation, 

 prate learnedly about Mr. Darwin's method, which is not 

 inductive enough, not Baconian enough, forsooth, for them. 

 But even if practical acquaintance with the process of 

 scientific investigation is denied them, they may learn, by 

 the perusal of Mr. Mill's admirable chapter " On the Deduc- 

 tive Method," that there are multitudes of scientific inquiries, 

 in which the method of pure induction helps the investigator 

 hut a very little way. 



" The mode of investigation," says Mr. Mill, "which, from the 

 proved inapplicability of direct methods of observation and experi- 

 ment, remains to us as the main source of the knowledge we possess, 



