species as to variation; etc. 101 



gous to it, from inorganic to organic Nature, and in 

 the latter to connect the present with the past in some 

 sort of material connection. The generalization may 

 indeed be expressed so as not to assert that the con- 

 nection is genetic, as in Mr. Wallace's formula : " Ev- 

 ery species has come into existence coincident both in 

 time and space with preexisting closely-allied species." 

 Edward Forbes, who may be called the originator of 

 this whole line of inquiry, long ago expressed a simi- 

 lar view. But the only material sequence we know, 

 or can clearly conceive, in plants and animals, is that 

 from parent to progeny ; and, as De Candolle implies, 

 the origin of species and that of races can hardly be 

 much unlike, nor governed by other than the same 

 laws, whatever these may be. 



The progress of opinion upon this subject in one 

 generation is not badly represented by that of De Can- 

 dolle himself, who is by no means prone to adopt new 

 views without much consideration. In an elementary 

 treatise published in the year 1835, he adopted and, if 

 we rightly remember, vigorously maintained, Schouw's 

 idea of the double or multiple origin of species, at 

 least of some species — a view which has been carried 

 out to its ultimate development only perhaps by Agas- 

 siz, in the denial of any necessary genetic connection 

 among the individuals of the same species, or of any 

 original localization more restricted than the area now 

 occupied by the species. But in 1855, in his u Geogra 

 phie Botanique," the multiple hypothesis, although in 

 principle not abandoned, loses its point, in view of the 

 probable high antiquity of existing species. The act- 

 ual vegetation of the world being now regarded as a 



