FUNDAMENTAL RELATIONS OF ANIMALS 59 



gratuitous. On the contrary, it is known by the evidence funished by 

 the Egyptian monuments and by the most careful comparison between 

 animals found in the tombs of Egypt with living specimens of the 

 same species obtained in the same country that there is not the 

 shadow of a difference between them for a period of about five thou- 

 sand years. These comparisons, first instituted by Cuvier, have proved 

 that as far as it has been possible to carry back the investigation, it 

 does not afford the beginning of an evidence that species change in 

 the course of time, if the comparisons be limited to the same great 

 cosmic epoch.'^'^ Geology only shows that at different periods^^ there 



■" [This was a standard argument of special creationists. They hardly understood that 

 in terms of the life history of species five thousand years was an infinitesimal span of 

 time.] 



" I trust no reader will be so ignorant of the facts here alluded to as to infer from 

 the use of the word "period" for different eras and epochs of great length, each of 

 which is characterized by different animals, that the differences these animals exhibit 

 is in itself evidence of a change in the species. The question is whether any changes 

 take place during one or any of these periods. It is almost incredible how loosely some 

 people will argue upon this point from a want of knowledge of the facts, even though 

 they seem to reason logically. A distinguished physicist has recently taken up this 

 subject of the immutability of species and called in question the 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 former 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 partic- 

 ular 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 follow 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 period, no matter how many or how few, the 

 question remains simply this: When the change takes place, does it take place 

 spontaneously under the action of physical agents, according to their law, or is it 

 produced by the intervention of an agency not in that way at work before or after- 

 wards? A comparison 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 different 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 system of 

 rocks to another. But because these works bear a closer resemblance as 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 supposed case. It is not because species have lasted for a longer or shorter 

 time in past ages that naturalists consider them as immutable, but because in the 

 whole series of geological ages, taking the entire lapse of time which has passed since 



