52 



ESSAY ON CLASSIFICATION. 



Part I. 



different sjjecies ; but no transition from those of a preceding into those of the 

 following epoch has ever been noticed any^vhere; and the question alluded to here is 

 to be distinguished from that of the origin of the differences in the bvdk of species 

 belonging to two different geological eras. The question we are now examining 

 involves only the fixity or mutabihty of species during one epoch, one era, one 

 period in the history of our globe. And nothing furnishes the slightest argument in 



this point from a want of knowledge of the facts, 

 even though they seem to reason logically. A dis- 

 tinguished physicist has recently taken up this sub- 

 ject of the immutability of species, and called in 

 question tlie logic of those who uphold it. I will 

 put his argument into as few words as possible, 

 and show, I hope, that it does not touch the case. 

 " Changes are observed from one geological period 

 to another; species which do not exist at an earlier 

 period are observed at a later period, while the for- 

 mer have disappeared ; and though each species may 

 have possessed its peculiarities unchanged for a lapse 

 of time, the fact that when long periods are con- 

 sidered, all those of an earlier period are replaced 

 by new ones at a later period, proves that species 

 change in the end, provided a sufficiently long period 

 of time is granted." I have nothing to object to the 

 statement of facts, as far as it goes, but I maintain 

 that the conclusion is not logical. It is true that 

 species are limited to particular geological epochs; 

 it is equally true that, in all geological formations, 

 those of successive periods are different, one from 

 the other. But because they so differ, does it fol- 

 low that they have changed, and not been exchanged 

 for, or replaced by others ? The length of time 

 taken for the operation has nothing to do with the 

 argument. Granting myriads of years for each pe- 

 riod, no matter how many or how few, the question 

 remains simply this : Wlien the change takes place, 

 does it take place spontaneously, under the action of 

 physical agents, according to their law, or is it pro- 

 duced by the intervention of an agency not in tliat 

 way at work before or afterwards ? A eoinparison 

 may explain my view more fully. Let a lover of 

 the fine arts visit a museum arranged systematically, 

 and in which the works of the ditferent schools are 

 placed in chronological order ; as he passes from one 



room to another, he beholds changes as great as those 

 the paleontologist observes in passing from one sys- 

 tem of rocks to another. But because these works 

 bear a closer resemblance iis they belong to one or 

 the other school, or to periods following one another 

 closely, would the critic be in any way justified 

 in assuming that the earlier works have changed 

 into those of a later period, or to deny that they 

 are the works of artists living and active at the 

 time of their production ? The question about the 

 immutability of species is identical with this sup- 

 posed case. It is not because species have lasted 

 for a longer or shorter time in past ages, that nat- 

 uralists consider them as innnutable, but because in 

 the whole series of geological ages, taking the entire 

 lapse of time which has passed since the first intro- 

 duction of animals or plants upon earth, not the 

 slightest evidence has yet been produced that sjsecies 

 are actually transformed one into the other. We 

 only know that they are different at different periods, 

 as are works of art of difterent periods and of differ- 

 ent schools ; but as long as we have no other data to 

 reason upon than those geology has furnished, to this 

 day, it is as unphilosophical and illogical, because 

 such differences exist, to assume that species do 

 change, and have changed, that is, are transformed, 

 or have been transformed, as it would be to main- 

 tain that works of art change in the course of time. 

 We do not know how organized beings have origi- 

 nated, it is true ; no naturalist can be prepared to 

 account for their appearance in the beginning, or for 

 their difference in different periods ; but enough is 

 known to repudiate the assumption of their transmu- 

 tation, as it does not explain the fiicts, and shuts out 

 further attempts at proper investigations. See Ba- 

 den Powell's Essays, quoted above; p. 412, et 

 seq., and Essay 3d, generally. 



