174 ESSAY ON CLASSIFICATION 



dividuals of the same species is the prevailing characteristic of the 

 animal kingdom, while the fact is that a large number even of ani- 

 mals, not to speak of Man, select their mate for life and rarely have 

 any 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 revolting even to the 

 savage. Then again, there are innumerable species in which vast 

 numbers of individuals are never developed sexually, others in which 

 sexual individuals 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 distinctions and definitions, introduced 

 in our science during its infancy, are to be taken as standards for 

 our appreciation of the phenomena in nature, instead of framing 

 and remodelling our standards according to the laws of nature as our 

 knowledge extends. It is, for instance, a specific character 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 themselves. It is characteristic of the Mare, as the rep- 

 resentative 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 still other kinds of halfbreeds with 

 the Zebra, the Dauw, etc. And yet in face of all these facts, which ren- 

 der sexual reproduction, or at least promiscuous intercourse among 

 the representatives of the same species, so questionable a criterion of 

 specific identity, there are still naturalists who would represent it as 

 an unfailing test, only that they may sustain one single position, that 

 all men are derived from one single pair. 



These facts, with other facts which go to show more extensively 



