xvm 



variations and the extinction of others, is a necessary consequence of 

 severe competition. " Favourable variations " are those which are 

 better adapted to surrounding conditions. It follows, therefore, that 

 every variety which is selected into a species is so favoured and 

 preserved in consequence of being, in some one or more respects, 

 better adapted to its surroundings than its rivals. In other words, 

 every species which exists, exists in virtue of adaptation, and what- 

 ever accounts for that adaptation accounts for the existence of the 

 species. 



To say that Darwin has put forward a theory of the adaptation of 

 species, but not of their origin, is therefore to misunderstand the 

 first principles of the theory. For, as has been pointed out, it is 

 a necessary consequence of the theory of selection that every species 

 must have some one or more structural or functional peculiarities, in 

 virtue of the advantage conferred by which, it has fought through 

 the crowd of its competitors and achieved a certain duration. In 

 this sense, it is true that every species has been "originated" by 

 selection. 



There is another sense, however, in which it is equally true 

 that selection originates nothing. " Unless profitable variations 



occur natural selection can do nothing" ('Origin,' Ed. I, 



p. 82). " Nothing can be effected unless favourable variations 

 occur" (ibid., p. 108). "What applies to one animal will apply 

 throughout time to all animals — that is, if they vary — for otherwise 

 natural selection can do nothing. So it will be with plants " (ibid., 

 p. 113). Strictly speaking, therefore, the origin of species in general 

 lies in variation ; while the origin of any particular species lies, firstly, 

 in the occurrence, and secondly, in the selection and preservation of a 

 particular variation. Clearness on this head will relieve one from the 

 necessity of attending to the fallacious assertion that natural selec- 

 tion is a deus ex machind, or^cculfc agency. 



Those, again, who confuse the operation of the natural causes 

 which bring about variation and selection with what they are pleased 

 to call " chance " can hardly have read the opening paragraph of the 

 fifth chapter of the ' Origin ' (Ed. I, p. 131) : " I have sometimes 

 spoken as if the variations .... had been due to chance. This 

 is of course a wholly incorrect expression, but it seems to acknow- 

 ledge plainly our ignorance of the cause of each particular variation." 



Another point of great importance to the right comprehension of 

 the theory, is, that while every species must needs have some adap- 

 tive advantageous characters to which it owes its preservation by 

 selection, it may possess any number of others which are neither 

 advantageous nor disadvantageous, but indifferent, or even slightly 

 disadvantageous. (Ibid., p. 81.) For variations take place, not 

 merely in one organ or function at a time, but in many ; and thus 



