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always a slow process." What I mean is, that everything is 

 modified by Natural Selection, but that Natural Selection can 

 modify nothing unless it be already modified, or in other and in 

 still plainer words, that unless animals or plants begin to change, 

 they never will be changed. A very recondite argument, is it 

 not ? I hope you don't mean to attempt to dispute it. 



I believe, I "suspect," that an "occasional intercross with a 

 distinct individual is a law of nature. I am well aware that there 

 are, on this view, many cases of difficulty, some of which I am 

 trying to investigate." Right or wrong, therefore, you must 

 take for granted that any difficulty either has been, or will be, 

 solved by me. That is a matter of course. 



I believe that if I only " suspect" a new law of nature, a new 

 law of nature there must be. Is is not six of one and half-a- 

 dozen of the other ? What can be fairer ? 



I believe, that is to say, that this new law brings about 

 occasional exceptions only occasionally. That I consider a 

 grand discovery, worthy of Aristotle, Pliny, Plato, or Solomon 

 himself. 



I believe that the several species of a genus " must have 

 proceeded from the same source, as they had descended from the 

 same "progenitor," although " undoubtedly there are many cases 

 of extreme difficulty in understanding how the same species could 

 possibly have migrated from some one point to the several distant 

 and isolated points where now found." For instance, " why do 

 we not find a single animal common to Europe and Australia and 

 South America?" the conditions of life are the same. The 

 answer, I believe, is that the animals have not been able to 

 migrate. I grant you that there are as many animals in each of 

 the same genus as formerly, and which must, therefore, have 

 " descended from the same progenitor." There they are ; they 

 can't have mii:Tutc-<l. They must have been, I say, separately 

 created. Yet, there they are ! I do not, either, believe that 

 continents " which are now quite separate have been continuously 

 or almost continuously, united with each other ; so that I do not 

 " for a moment pretend that any explanation could be afforded of 

 many such cases," but as they or my theory must give way, I 



