254 ESSAY ON CLASSIFICATION. 



intercourse with others. It is a fact known to every farmer, 

 that different breeds of the same species are less inclined to 

 mingle than individuals of the same breed. For my own 

 part, I cannot conceive how moral philosophers, who urge 

 the unity of origin of Man as one of the fundamental 

 principles of their religion, can at the same time justify 

 the necessity which it involves of a sexual intercourse 

 between the nearest blood relations of that assumed first 

 and unique human family, when such a connection is re- 

 volting even to the savage. Then again, there are innu- 

 merable species in which vast numbers of individuals are 

 never developed sexually, others in which sexual indivi- 

 duals appear only now and then at remote intervals, while 

 many intermediate generations are produced without any 

 sexual connection, and others still which multiply more 

 extensively by budding than by sexual generation. I 

 need not again allude here to the phenomena of alternate 

 generation, now so well known among Acalephs and 

 Worms, nor to the polymorphism of many other types. 

 Not to acknowledge the significance of such facts, would 

 amount to the absurd pretension, that we are to take 

 distinctions and definitions, introduced into our science 

 during its infancy, as standards for our appreciation of the 

 phenomena of nature, instead of framing and remodelling 

 our standards, according to the laws of nature, as our 

 knowledge extends. It is, for instance, a specific cha- 

 racter of the Horse and the Ass to be able to connect 

 sexually with each other, and thus to produce an offspring 

 different from that which they bring forth among them- 

 selves. It is characteristic of the Mare, as the representa- 

 tive of its species, to bring forth a Mule with the Jackass, 

 and of the Stallion to procreate Hinnies with the She-ass. 

 It is equally characteristic of them to produce again other 



