250 ESSAY ON CLASSIFICATION. 



sexual connexion, which so naturally brings together the 

 individuals of the same species in the function of repro- 

 duction. But I hold that this is a complete fallacy, or at 

 least a petitio principii, not admissible in a philosophical 

 discussion of what truly constitutes the characteristics of 

 species. I am even satisfied that some of the most per- 

 plexing problems involved in the consideration of the 

 natural limits of species would have been solved long ago 

 had it not been so generally urged that the ability and 

 natural disposition of individuals to connect themselves 

 in fertile sexual intercourse was of itself sufficient evidence 

 of their specific identity. Without alluding to the fact, 

 that every new case of hybridity 1 is an ever-returning 

 protest against such an assertion; and without entering 

 here into a discussion respecting the possibility or practi- 

 cability of setting aside this difficulty by introducing the 

 consideration of the limited fertility of the progeny of 

 individuals of different species, I will only remark, that, 

 as long as it is not proved that all the varieties of dogs, 

 and of any others of our domesticated animals and of our 

 cultivated plants, are respectively derived from one un- 

 mixed species; and as long as doubts may be entertained 

 respecting the common origin of all races of men from 

 one common stock, it is not logical to admit that sexual 

 connexion, resulting even in fertile offspring, is a trust- 

 worthy evidence of specific identity. 



To justify this assertion I would only ask, Where is the 



1 WIEGMAN, Gekronte Preisschrift Hybridity in Animals, and on some 



iiber die Bastarderzeugung im Pflan- collateral subjects ; Charleston Med. 



zenreich ; Braunschweig, 1828, 8vo. Journ., 1850. DE SELYS LONG- 



BRAUN (A.), Ueber die Erschein- CHAMPS, Recapitulation des hybrides 



uug der Verjiiugung in der Natur; observes dans la famille des Anati- 



Freiburg, 1849, 4to. MORTON (S. dees, Bull. Ac. Brux., 1845 ; and 



G.), Essay on Hybridity, Amer. Juuru., Additions, ibid., 185(5, 2cle part., page 



1847. Additional Observations on 6. 



