Bibliographical Notices. 401 



used " to hide our ignorance." Under any circumstances, we come 

 back to a theory very analogous to that of Lamarck — that of varia- 

 bility, with gradually increasing perfection of organization, within 

 certain definite limits laid down by a higher ])ower ; and it appears 

 to us that Mr. Darwin's theory must be regarded in the same light 

 as those of his jiredecessors, namely as an attempt (perhaps a better 

 one than any that have gone before) to account for phenomena 

 which are not proved to occur. For, after all, before we can regard 

 any theory of evolution as deserving notice, we must look for some 

 little evidence that such a thing as the production of one species from 

 another pre-existing one has taken place. 



In seeking this evidence, it is clear that we must not expect to find 

 it unequivocally expressed among existing plants and animals. Never- 

 theless, if species be, as Mr. Darwin's theory would make them, 

 nothing else than more strongly-marked varieties, or, at least, forms 

 in which the divergences from the last specific type have been accu- 

 mulated to such an extent as to give rise to what we regard as distinct 

 species, it would appear that we ought to be able to find some traces 

 of such changes taking place within historical periods. But when 

 we come to investigate the facts of the case, we find that the balance 

 of probabihty is in favour of species being liable to definite degrees of 

 variation dependent on the external conditions of life* ; and although 

 some varieties of the same species may differ sufficiently from each 

 other, or even from the specific type, to have induced naturalists to 

 describe them as distinct species, such errors have generally been 

 due either to imperfect information, or to the augmentation of the 

 importance of differences into which the close study of a limited 

 group of objects is liable to lead the student, especially of a local 

 fauna or flora. That there may be differences of opinion among 

 good naturalists as to the limits of a species, every one will admit ; 

 but whether this fact is to be used, as has been done by Darwin, as 

 an argument in the discussion of a theory in natural history is quite 

 another question. 



It is, however, to geology that we must turn to seek anything like 

 reliable evidence of the evolution of species. In the successive strata 

 of the earth's crust, if anywhere, we must find the traces of that 

 "interminable number of intermediate forms" necessary to conduct 

 us step by step from the primordial germ of the evolutionists to the 

 most liighly organized members of the animal and vegetable king- 

 doms. Bnt Mr. Darwin himself admits that we do not find them— 

 that " we meet with no such evidence" of " the gradation and muta- 

 tion of the forms of Hfe ;" and he can only get over this difficulty by 

 assuming " that the geological record is far more imperfect than most 



* It appears to ns that even the celebrated ])igeon-experiments of Mr. 

 Darwin are confirmatory of tins view : hardly any evidence of the perma- 

 nence of species can be stronger than that a bird, after many ages of varia- 

 tion under domestication and the jiroduction of varieties so widely different 

 as those of pigeons, should still retain tlie impress of the original type so 

 strongly as to revert to it by the simple intermixture of two extreme 

 forms. 



