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DARWIN AND THE ORIGIN OF SPECIES. 1 



THE theory proposed by Mr. Darwin as sufficient to account 

 for the origin of species has been received as probable, and 

 even as certainly true, by many who from their knowledge of 

 physiology, natural history, and geology, are competent to form 

 an intelligent opinion. The facts, they think, are consistent 

 with the theory. Small differences are observed between 

 animals and their offspring. Greater differences are observed 

 between varieties known to be sprung from a common stock. 

 The differences between what have been termed species are 

 sometimes hardly greater in appearance than those between 

 varieties owning a common origin. Even when species differ 

 more widely, the difference, they say, is one of degree only, 

 not of kind. They can see no clear, definite distinction by 

 which to decide in all cases whether two animals have sprung 

 from a common ancestor or not. They feel warranted in con- 

 cluding, that for aught the structure of animals shows to the 

 contrary, they may be descended from a few ancestors only- 

 nay, even from a single pair. 



The most marked differences between varieties known to 

 have sprung from one source have been obtained by artificial 

 breeding. Men have selected, during many generations, those 

 individuals possessing the desired attributes in the highest 

 degree. They have thus been able to add, as it were, small 

 successive differences, till they have at last produced marked 

 varieties. Darwin shows that by a process, which he calls 

 natural selection, animals more favourably constituted than 

 their fellows will survive in the struggle for life, will produce 

 descendants resembling themselves, of which the strong will 



1 Eeview of Darwin's Origin of Species : from the North British Review, 

 June 1867. 



