HYBEIDITY. FECUNDITY. 25 



parent stock. What, indeed, would be the signification of 

 specific differences in nature, and how objectless would be 

 their permanence, if their obliteration were rendered possible 

 by continued production of hybrids ! 



Morton, the predecessor of Vogt, in this respect has endea- 

 voured to show that hybrids of different species are the more 

 prolific between themselves, the greater their capacity to be- 

 come domesticated. His examples refer chiefly to the hprse, 

 the ass, the zebra, the wolf, dog, jackal, fox, the swine, fowls ; 

 and it cannot be denied that, according to his examples, the 

 phenomena of hybridity possess a greater extension than was 

 formerly admitted. He concludes therefrom that, as regards 

 man pre-eminently a domestic animal, the inference from 

 unlimited fecundity to unity of species is not applicable ; and 

 his successors, Nott and Gliddon, distinguished accordingly, 

 among the various species of animals, those which by intermix- 

 ture produce none, or unprolific, or prolific hybrids as remote, 

 allied, and proximate species. The so-called races of mankind 

 are said to stand in the latter relation, as the permanence of 

 their organic peculiarities, as well as those of the races of dogs, 

 is ascertainable from the ancient Egyptian monuments. As 

 this last assertion leads us to the notoriously erroneous pro- 

 position, that there is, properly speaking, no alteration of type, 

 the question of hybridity itself is placed upon very slippery 

 ground, since the majority of domestic animals have ever been 

 subjects of contention as regards unity or difference of species, 

 and are consequently least adapted to lead to a decisive solu- 

 tion. 



There certainly prevails in modern times an inclination to 

 assume a plurality of species, where formerly races only were 

 distinguished; and in proportion as this has been done, 

 fecundity alone as a decisive mark of unity of species has lost 

 its weight. We must not omit to state that this is especially the 

 case if unity of species is considered as identified with unity 

 of descent, in which case fecundity affords no absolute proof 

 for common origin, if stocks originally distinct prove themselves 

 productive between each other. The question would, however, 

 still remain, whether by distinguishing stock from species 



