40 HYBRIDS AND MONGRELS COMPARED. [Chap. IX. 



to ine, 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 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 I have myself seen striking 

 instances of this fact. Gartner further admits that 

 hybrids between very closely allied species are more 

 variable than those from very distinct species; and 

 this shows that the difference in the degree of variabil- 

 ity graduates away. When mongrels and the more 

 fertile hybrids are propagated for several generations, 

 an extreme amount of variability in the offspring in 

 both cases is notorious; but some few instances of both 

 hybrids and mongrels long retaining a uniform charac- 

 ter could be given. The variability, however, in the 

 successive generations of mongrels is, perhaps, greater 

 than in hybrids. 



This greater variability in mongrels than in hybrids 

 does not seem at all surprising. For the parents of 

 mongrels are varieties, and mostly domestic varieties 

 (very few experiments having been tried on natural 

 varieties), and this implies that there has been recent 

 variability, which would often continue and would 

 augment that arising from the act of crossing. The 

 slight variability of hybrids in the first generation, in 

 contrast with that in the succeeding generations, is a 

 curious fact and deserves attention. For it bears on 

 the view which I have taken of one of the causes of 



