12 



THE EYOLUTION OP BIEDS. 



Darwin's 

 use of the 

 •word for- 

 tuitous. 



Artificial 

 selection. 



Evolution 

 solely teleo- 

 loffical. 



Eeneficial 

 variation. 



cause. The term accidental is used in a relative, not in an absolute, sense. When 

 he speaks of fortuitous variation, he does not mean that the variation occurred without a 

 sufficient cause ; but that having been produced by an unknown cause, the fact of its 

 being a beneficial or a harmful variation, or neither one nor the other (neutral in fact), is an 

 accident. 



Those naturalists who believe in the " swamping effects of interbreeding " hold that 

 the modification of a species by the careful selection of a special variation for many 

 generations can only be produced artificially, by preventing the interbreeding of individuals 

 possessing the variation with those that do not, and by picking out two or more indi- 

 viduals who possess a similar variation, and isolating them, so that they may interbreed 

 only with those that do. 



A consequence of this assumption is that, in order to modify a species without artificial 

 means, there must be special variation arising simultaneously amongst a number of 

 individuals in the same locality for many generations. Variations of this kind could not 

 in any sense be accidental, and must be produced either by the pecuUar environment of 

 the species during its continuance, or proceed from an innate tendency in the species 

 itself. 



To say that Plants and Animals " have an innate tendency towards perfection or pro- 

 gressive development," is to prove too much. Evolution, apparently, takes place only 

 when it is required. Some of the simplest forms of animal life appear to have lived on 

 unchanged for countless ages, showing no tendency towards progressive development. It 

 is fair to assume that they are exactly adapted to their environment, and that any change 

 in the direction of progressive development would be to their disadvantage. That they 

 remain unchanged may be explained in two ways. One theory assumes that, although 

 there have been during the lifetime of the least complex species a practically infinite series 

 of slight modifications, none of them have been beneficial to the species, and therefore 

 none of them have survived. The other theory admits that a variety of causes must have 

 produced a variety of isolated variations from time to time, which, being isolated, therefore 

 did not survive. 



Animals appear to have an innate tendency towards development, if the modifications 

 so caused are for the immediate or even ultimate benefit of the species. Expressed in 

 other words, the fact appears to be that this innate tendency lies dormant until aroused 

 by a sense of need or by a state of need. Instead therefore of using the term accidental 

 variation, the terms beneficial variation or teleological variation must be used. 



The theory of Teleological or Beneficial Variation is apparently open to two objections. 

 In the first place, it only covers part of the ground ; and in the second place, it can 

 scarcely be regarded as less miraculous than special creation. That it only covers part of 

 the ground is self-evident, if we admit that many, we might almost say most, specific 

 differences are of so trivial a nature that we cannot conceive them to be of any use. In 

 point of fact, the theory of Beneficial Variation can only be applicable to the variations that 



