o(;,j HYBRIDS AND MONGRELS COMPARED. Chap. VIII. 



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

 namel}', by reciprocal crosses, and he found their mongrel ofl- 

 sprinf^ perfectly fertile. But one of these five varieties, when 

 used either as the father or mother, and crossed with the Nico- 

 tiana glutinosa, always yielded hybrids not so sterile as those 

 which were produced from the four other varieties when crossed 

 with Nicotiana glutinosa. Hence the reproductive system of 

 this one variety must have been in some manner and in some 

 degree modified. 



From these facts it cannot be maintained that varieties 

 when crossed are invariably (luitc fertile : from the great diffi- 

 culty of ascei'taining 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 liis domestic va- 

 rieties, and from such varieties not having been exposed for a 

 very long period to uniform conditions of life. From these sev- 

 eral considerations we may conclude that fertility does not con- 

 stitute 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 vmknown nature in their 

 sexual elements. 



Hybrids and 3fonr/rels compared^ independently of their 

 Fertility. 



Independently of the quest i(m of fertility, the offspring of 

 species when crossed, and of varieties when crossed, may be 

 compared in several other respects. Giirtuer, whose strong 

 wish it was to draw a distinct line between species and varie- 

 ties, could find very few, and, as it seems to me, quite unim- 

 portant 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 im2:)ortant 

 respects. 



I shall here discuss this subject with extreme brevity. The 

 most important chstinction is, that in the first generation mon- 

 grels are more variable than hybrids ; but Gartner admits that 

 hybrids from species which have long been cultivated are often 

 variable in the first generation; and 1 have myself seen striking 

 instances of this fact. Gartner further admits that liybrida 

 between very closely-allied species are more variable than 



