242 HYBRIDS AND MONGRELS COMPARED. [CHAP. IX. 



Verbascum ; and although unable to confirm Gartner's results on 

 the crossing of the distinct species, he finds that the dissimilarly 

 coloured varieties of the same species yield fewer seeds, in the 

 proportion of 86 to 100, than the similarly coloured varieties. 

 Yet these varieties differ in no respect except in the colour of 

 their flowers ; and one variety can sometimes be raised from the 

 seed of another. 



Kolreuter, whose accuracy has been confirmed by every sub- 

 sequent observer, has proved the remarkable fact, that one 

 particular variety of the common tobacco was more fertile than 

 the other varieties, when crossed with a widely distinct species. 

 He experimented on five forms which are commonly reputed to 

 be varieties, and which he tested by the severest trial, namely, by 

 reciprocal crosses, and he found their mongrel offspring perfectly 

 fertile. But one of these five varieties, when used either as the 

 father or mother, and crossed with the Nicotiana glutinosa, 

 always yielded hybrids not so sterile as those which were pro- 

 duced from the four other varieties when crossed with N. glutinosa. 

 Hence the reproductive system of this one variety must have 

 been in some manner and in some degree modified. 



From these facts it can no longer be maintained that varieties 

 when crossed are invariably quite fertile. From the great diffi- 

 culty of ascertaining the infertility of varieties in a state of nature, 

 for a supposed variety, if proved to be infertile in any degree, 

 would almost universally be ranked as a species; from man. 

 attending only to external characters in his domestic varieties, 

 and from such varieties not having been exposed for very long 

 periods to uniform conditions of life; from these several con- 

 siderations we may conclude that fertility does not constitute a 

 fundamental distinction between varieties and species when 

 crossed. The general sterility of crossed species may safely be 

 looked at, not as a special acquirement or endowment, but as 

 incidental on changes of an unknown nature in their sexual 

 elements 



Hybrids and Mongrels compared, independently of their fertility. 



Independently of the question of fertility, the offspring of species 

 and of varieties when crossed may be compared in several other 

 respects. Gartner, whose strong wish it was to draw a distinct 

 line between species and varieties, could find very few, and, as it 

 seems to me, quite unimportant differences between the so-called 

 hybrid offspring of species, and the so-called mongrel offspring of 

 varieties. And, on the other hand, they agree most closely in 

 many important respects. 



I shall here discuss this subject with extreme brevity. The 

 most important distinction is, that in the first generation mongrels 



