DARWIN AND EIS REVIEWERS. 165 



npou different patterns of form, and embrace representatives 

 equally independent in their origin ; that genera are founded 

 upon altimate peculiarities of structure, embracing representa- 

 tives which, from the very nature of their peculiarities, could 

 have no community of origin; and that, finally, species are 

 based upon relations and proportions that exclude, as much as 

 all the preceding distinctions, the idea of a common descent. 



" As the community of characters among the beings belong- 

 ing to these different categories arises from the intellectual con- 

 nection which shows them to be categories of thought, they 

 cannot be the result of a gradual material differentiation of the 

 objects themselves. The argument on which these views are 

 founded may be summed up in the following few words: 

 Species, genera, families, etc., exist as thoughts, individuals as 

 facts." » 



An ingenious dilemma caps the argument : 



" It seems to me that there is much confusion of ideas in 

 the general statement of the variability of species so often re- 

 peated lately. If species do not exist at all, as the supporters 

 of the transmutation theory maintain, how can they vary ? and 

 if individuals alone exist, how can the differences which may be 

 observed among them prove the variability of species ? " 



Now, we imagine that Mr. Darwin need r.ot be 

 dangerously gored by either horn of this curious di- 

 lemma. Although we ourselves cherish old-fashioned 

 prejudices in favor of the probable permanence, and 

 therefore of a more stable objective ground of species, 

 yet we agree — and Mr. Darwin will agree fully with 

 Mr. Agassiz — that species, and he will add varieties, 

 " exist as categories of thought," that is ; as cognizable 

 distinctions — which is all that we can make of the 

 phrase here, whatever it may mean in the Aristotelian 

 metaphysics. Admitting that species are only cate- 



1 la American Journal of Science, July, 1860, p. 143. 

 8 



