SPECIES AS TO VARIATION, ETC. 201 



These peculiar views, if sustained, will effectually 

 dispose of every form of derivative hypothesis. 



Returning for a moment to De Candolle's article, 

 we are disposed to notice his criticism of Linnaeus' s 

 u definition " of the term species (Philosophia Botani- 

 ca, No. 157) : " Species tot numeramus quot diversce 

 formce in principio sunt creates" — which he declares 

 illogical, inapplicable, and the worst that has been pro- 

 pounded. " So, to determine if a form is specific, it 

 is necessary to go back to its origin, which is impos- 

 sible. A definition by a character which can never 

 be verified is no definition at all." 



Now, as Linnaeus practically applied the idea of 

 species with a sagacity which has never been surpassed, 

 and rarely equaled, and indeed may be said to have 

 fixed its received meaning in natural history, it may 

 well be inferred that in the phrase above cited he did 

 not so much undertake to frame a logical definition, 

 as to set forth the idea which, in his opinion, lay at 

 the foundation of species ; on which basis A. L. 

 Jussieu did construct a logical definition — " Nunc 

 rectius definitur perennis individuorum similium suc- 

 cessio continuata generatione renascentiun." The fun- 

 damental idea of species, we would still maintain, is 

 that of a chain of which genetically-connected individ- 

 uals are the links. That, in the practical recognition 

 of species, the essential characteristic has to be inferred, 

 is no great objection — the general fact that like engen- 

 ders like being an induction from a vast number of 

 instances, and the only assumption being that of the 

 uniformity of Nature. The idea of gravitation, that 

 of the atomic constitution of matter, and the like, 



