316 MISCELLANEOUS OBJECTIONS TO THE [Chap. VIL 



are related in the closest manner to other species that 

 still exist, or have lately existed; and it will hardly be 

 maintained that such species have been developed in an 

 abrupt or sudden manner. Nor should it be forgotten, 

 when we look to the special parts of allied species, in- 

 stead of to distinct species, that numerous and wonder- 

 fully fine gradations can be traced, connecting together 

 widely different structures. 



Many large groups of facts are intelligible only on 

 the principle that species have been evolved by very 

 small steps. For instance, the fact that the species in- 

 cluded in the larger genera are more closely related to 

 each other, and present a greater number of varieties 

 than do the species in the smaller genera. The former 

 are also grouped in little clusters, like varieties round 

 species, and they present other analogies with varieties, 

 as was shown in our second chapter. On this same prin- 

 ciple we can understand how it is that specific characters 

 are more variable than generic characters; and how the 

 parts which are developed in an extraordinary degree or 

 manner are more variable than other parts of the same 

 species. Many analogous facts, all pointing in the same 

 direction, could be added. 



Although very many species have almost certainly 

 been produced by steps not greater than those separating 

 fine varieties; yet it may be maintained that some have 

 been developed in a different and abrupt manner. Such 

 an admission, however, ought not to be made without 

 strong evidence being assigned. The vague and in 

 some respects false analogies, as they have been shown 

 to be by Mr. Chauncey Wright, which have been advanced 

 in favour of this view, such as the sudden crystallisation 

 of inorganic substances, or the falling of a facetted 



