THE HUMAN SPECIES. 115 



from the lowest up to the most complicated ; and there- 

 fore, when applied to mankind, it is of little weight, 

 since even the exceptional law, assumed by the writer 

 who regards the human races as necessarily of one 

 species only, is more likely to operate in the usual 

 generical form of animated beings, than by acting in- 

 versely, granting to one specified type, the attributes 

 that belong, in all other instances, to a genus ; and so 

 far supporting his own doctrine of a progressive crea- 

 tion. In physics, dogmas are admissible only so long 

 as they are not disproved. Since the fissiparous pro- 

 pagation of some animals is established, " Omne animal 

 ex ovo" is no longer asserted to be an universal maxim, 

 nor that all parturition of mammalia is derived wholly 

 from uterine gestation ; for, without referring to classes 

 of a lower organization, fertile offspring is obtained 

 among several genera of brute mammals, from the 

 union of two or more so called distinct species ; or the 

 definition of that word is several ways incorrect. 

 Frederic Cuvier, sensible of the fallacy embodied in 

 the maxim above quoted, endeavoured to prop it up by 

 an argument drawn from the asserted gradual decrease 

 of prolific power, in a breed of hybrids, obtained from 

 the union of a wolf and dog, reared by Buffon, an 

 experiment often referred to, but not carried out with 

 the care and perseverance required to render it of 

 substantial weight. 



We have, for example, among carnassiers, the wolf, 

 dhole, chakal, and dog ; that is, all the diurnal canidse, 

 if the dogma were true, would form only one species 



I. 



