XIL] THE ORIGIN OF SPECIES. 257 



ingenuity has not hitherto enabled us to pick holes of any great 

 importance ; and judging by what we hear and read, other 

 adventurers in the same field do not seem to have been much 

 more fortunate. It has been urged, for instance, that in his 

 chapters on the struggle for existence and on natural selection, 

 Mr. Darwin does not so much prove that natural selection does 

 occur, as that it must occur ; but, in fact, no other sort of demon 

 stration is attainable. A race does not attract our attention in 

 Nature until it has, in all probability, existed for a considerable 

 time, and then it is too late to inquire into the conditions of its 

 origin. Again, it is said that there is no real analogy between 

 the selection which takes place under domestication, by human 

 influence, and any operation which can be effected by Nature, 

 for man interferes intelligently. Reduced to its elements, this 

 argument implies that an effect produced with trouble by an 

 intelligent agent must, a fortiori, be more troublesome, if not 

 impossible, to an unintelligent agent. Even putting aside the 

 question whether Nature, acting as she does according to definite 

 and invariable laws, can be lightly called an unintelligent agent, 

 such a position as this is wholly untenable. Mix salt and sand, 

 and it shall puzzle the wisest of men, with his mere natural 

 appliances, to separate all the grains of sand from all the grains 

 of salt ; but a shower of rain will effect the same object in ten 

 minutes. And so, while man may find it tax all his intelligence 

 to separate any variety which arises, and to breed selectively 

 from it, the destructive agencies incessantly at work in Nature, 

 if they find one variety to be more soluble in circumstances than 

 the other, will inevitably, in the long run, eliminate it. 



A frequent and a just objection to the Lamarckian hypothesis 

 of the transmutation of species is based upon the absence of 

 transitional forms between many species. But against the 

 Darwinian hypothesis this argument has no force. Indeed, one 

 of the most valuable and suggestive parts of Mr. Darwin s work is 

 that in which he proves, that the frequent absence of transitions 

 is a necessary consequence of his doctrine, and that the stock 

 whence two or more species have sprung, need in no respect be 



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