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Rev. George Henslow on Natural Selection. 



IN Natural Science of July Mr. Henslow makes some statements 

 with regard to variation and Natural Selection which call fo^ 

 critical remark. He says that, though cultivated plants vary indefinitely, 

 and therefore require selection to produce definite modifications, this is 

 not the case in Nature — " Variation in Nature is always in strict adap- 

 tation to the direct action of the environment ; in other words, natural 

 variation is always definite." This statement seems to me so extraordinary, 

 and so opposed to well-known facts, that I can only impute it to the use 

 of the terms "vary" and "variation" in two very distinct senses ; first, 

 as meaning those individual variations which occur abundantly both 

 in nature and under cultivation ; and, secondly, as meaning those 

 particular variations which alone survive under nature and produce a 

 "variety" or a "species." In this latter sense, of course, " natural 

 variation " is definite ; but so, in the same sense, are the variations 

 of cultivated plants. From unstable and indefinite " variations " man 

 and nature alike produce definite " varieties." As one out of the 

 innumerable examples of indefinite variation which might be named 

 are the fifteen different modes of variation observed by Alph. de 

 Candolle on a single oak tree, while in a great number of common 

 species an equal amount of variability may be observed both in wild 

 and cultivated individuals ; and all these variations are indefinite, in 

 the sense that they do not usually occur in one direction only, from the 

 typical form. A few examples of such variations have been given in 

 my "Darwinism," pp. 76-80. I cannot, therefore, understand either 

 the meaning or the value of the statement — " natural variation is always 

 definite.''' 



It is not quite clear whether Mr. Henslow admits the agency of 

 Natural Selection at all. He says : "I would ask what facts are 

 producible to prove that Natural Selection acts at all on the main- 

 tenance, if not the origin, of any floral and, indeed, other structures ? " 

 It is, of course, admitted that direct proof of the action of Natural Selec- 

 tion is at present wanting ; but the indirect proofs have been so 

 cogent as to overcome the most violent prejudice and opposition, and 

 to convert a large majority of naturalists to a belief in its agency. It 

 is, therefore, rather late in the day to deny its existence without 



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