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THE AMERICAN NATURALIST [Vol. XLII1 



influence in moulding opinion, while Ms later views 

 are more in accord with scientific knowledge. Further- 

 more, it must be borne in mind that Darwin was the great 

 apostle of origin by descent. It was his unique mission 

 to bring the scientific world to accept this doctrine, a task 

 of such magnitude that methods of origin, for the time 

 at least, were relatively unimportant. In attempting to 

 determine Darwin's actual contribution, one is confronted 

 by the task of deciding how much credit is to be given to 

 the discoverer of a new idea or principle, and how much 

 to him who applies it and establishes it. It is fairly well 

 known that Darwin was not the first to formulate the prin- 

 ciple of evolution. Even in regard to natural selection, 

 often accepted as distinctly Darwinian, Darwin himself 

 has shown that he was anticipated by three other writers. 

 Yet the fact remains that Darwin has contributed more 

 to the foundations of biology than all of his forerunners. 



A careful rereading of the " Origin of Species" and the 

 "Variation of Animals and Plants under Domestication" 

 has been found necessary to make Darwin's views emerge 

 clearly from the mists of tradition and of recollection. It 

 has seemed desirable also that he should himself speak 

 in his own words, without the handicap of paraphrase 

 and of the personal equation. Together with the mani- 

 fest difficulty of making accurate and definite statements 

 of the consensus of botanical opinion on mooted ques- 

 tions, this necessarily results in a more or less frag- 

 mentary and detached account of such a vast field. 1 Its 

 value lies wholly in recalling to us Darwin's actual views 

 without interpretation or emendation, so that each may 

 determine for himself what part Darwin's work plays in 

 his own views, and in botanical opinion as he sees it. 



Distribution 



Darwin formulated three laws of distribution: (1) 

 Neither the similarity nor the dissimilarity of the in- 



(l^VflrZ 3 ^ 11 aftCT the Vari0US excer P ts ™ to the sixth edition 



- ^i th e f An^r Lt;tnt'; an ? to . he second edition (i875) ° f the 



"nuns ana riants under Domestication. ' » 



