5486 Zoology : its present Phasis 



at any period of their growth ? Must we, to explain these pheno- 

 mena, go back to the oldjeax de la Nature, to accident and chance, 

 to providence and the will of God ? What is the meaning of forms, 

 clearly arising from arrested developments, and of others as distinctly 

 traceable to retrogressive developments, but this, that adult species 

 may, after all, be only the individualized expression of certain forms 

 of life alone compatible with the existing order of things, as formed by 

 and out of this order itself; the basis, in the mean time, out of which 

 the living species springs — the trame, if we may so sa} r , being but 

 one with the extinct. In no other way can we readily connect the 

 past with the present, the present with that future which is sure to 

 come. The future, it is true, may be a world lifeless, cheerless, 

 rolling through space for millions of years, such as palaeontologists 

 supposed it to be at the commencement: we have no faith in either 

 conjecture. 



The modern theory, then, is that a continuous fecundity implies 

 species, a limited fecundity genus. All sheep and all cattle are con- 

 veniently assumed to possess (although this has never been proved) a 

 continuous fecundity, and therefore are, respectively, of one species; 

 the horse and the ass have a limited fecundity, and are therefore of 

 different species, but of the same genus ; the dog and fox do not 

 breed at all with each other ; they are, then, of different genera. 

 Beyond these, it is true, there may be no consanguinity by parentage 

 or reproduction ; but what is this to Nature ? Is it merely by way of 

 amusement, and to display her powers, that the embryo is found to 

 pass through so many of the same forms of life before attaining the 

 higher, occasionally reversing the process, and undergoing a retro- 

 grade development ? What precise meaning do zoologists attach to 

 the term parentage, when applied to different species of the same 

 genus ? According to one hypothesis, this is at least comprehensible : 

 " The young of all the species of the same genus possess at first all the 

 specific characters of the different species of the genus." * Unques- 

 tionably we have here parente of a deep character, and one which 

 Nature might turn to account. The conversion of one of these species 

 into another cannot be so difficult a matter with Nature, especially 

 when all or most of the specific characters are already present in the 

 youug. Thus a given species may perish, but another of the same 

 consanguinity takes its place in space : it is a question of time, not of 

 new creations ; it is but the successive developments of species from 

 one great family. How that family or genus stands with others has 

 not been as yet explained, and can only be by Palaeontology, which 

 gives us the matured specific and individualized forms of what, in the 

 living embryo, we can only guess at. The vertebrate have the most 

 positive relations to each other in the unity of their organization, and 

 especially of their skeleton. Thus parente extends from species to 

 genus and from genus to class and order, in characters not to be mis- 

 understood Cuvier maintained the doctrine of the fixity of species, 



* Knox, in the ' Zoologist' of 1856. 



