HOOKER AND THOMSON'S INDIAN FLORA. 65 



pregnating parent ; but would they return exactly to that 

 type, inheriting as they do a portion of the blood of a cognate 

 species ? And where — as not unf requently occurs — two or 

 more generally well-marked forms in nature are connected by 

 certain occasional individuals of intermediate character, is it 

 not very supposable that two species may have partially blended 

 in this way ? At any rate there is a vera causa, or what passes 

 as such, which requires to be taken into account, as has not 

 yet been done, so far as we know. This doubtless has oper- 

 ated in the case of cultivated plants, and contributed, along 

 with other causes, to the inextricable blending of certain 

 species. But we are not disposed to exaggerate its influence 

 in nature ; since we suppose, with Dr. Hooker, that wild 

 plants rarely hybridize. Yet the possibility and even the 

 probability of the occuiTence must not be overlooked in a 

 thorough discussion of the general question of the limitation 

 and permanence of species. 



However it may be as a blending influence, hybridization is 

 far from being a considerable, or the most potent cause of 

 the variation of species, since " the offspring of a hybrid has 

 never yet been known to possess a character foreign to those 

 of its parents." And we equally agree with our authors that 

 the known facts of the case " especially warn us not to con- 

 sider the influence of climate as paramount in determining 

 the distribution of species or the prevalence of forms," or 

 even as the most efficient cause of variation. What the cause 

 is that the legitimate offspring does occasionally possess a 

 character foreign to those of its parents we are wholly unable 

 to say ; but the fact is undoubted, and perhaps of more fre- 

 quent occurrence than is generally supposed. It is usual to 

 say that the abnormal forms originate only in cultivated or 

 domesticated individuals : it were perhaps better to say that 

 they were perpetuated, or are favorably situated for continua- 

 tion and full development, only under these circumstances, on 

 account of the greater segregation ; for of the very various 

 species of plants which are cultivated none are free from the 

 tendency to " sport " into races, whether of ancient or of 

 recent introduction. "Why their existence is so transitory in 



