8 CHAPTERS ON EVOLUTION. 



living beings. Over-population means a struggle for food and 

 for other conditions of life, such a consideration being 

 really the doctrines of " Parson Malthus " applied to the 

 animal and plant worlds at large. Hence it follows that as some 

 forms will be better adapted (by variation) than others to their 

 surroundings, the former will come to the front in the struggle. 

 Nature, so to speak, will "select" those individuals which 

 best adapt themselves to their surroundings, and will leave 

 the rest to perish. This is the " survival of the fittest." The 

 change of surroundings, already postulated, will further 

 induce and perpetuate variations in those individuals which 

 survive. 



Sixthly. A premium is thus set by nature upon variation, inas- 

 much as the varying and surviving individuals will transmit 

 their peculiarities to their offspring. 



Seventhly. Thus "varieties" of a species are first produced; 

 the "varieties" becoming permanent, form "races;" and the 

 " races," in time, differ so markedly from the original species 

 whence they were derived, as to constitute new "species." 



Eighthly. Past time has been, to all intents and purposes, 

 infinite. Hence it is probable that the existent species of 

 animals and plants have been evolved (through "natural 

 selection," acting through long periods of time) from a few 

 primitive and simple forms of life, or possibly from one such 

 form alone. 



Such is a summarised statement of Mr. Darwin's views. His 

 theory of " Sexual Selection " may be viewed as supplementary to 

 that of natural selection, and as serving likewise to account for 

 certain phenomena of which the former takes little heed. The pro- 

 cess of sexual selection is that whereby the males of many species 

 secure the females after contests. The result of these contests is 

 that the stronger and victorious males will transmit to their offspring 

 any peculiarities of form or constitution which they themselves pos- 

 sess, and in virtue of which they became victors over others. In 

 this way variation is again seen to be favoured. Then, secondly, the 

 "selection "of a mate is often determined, not by the males, but by 

 the females. In such a case it is assumed that those males which 

 exhibit (as seen typically amongst birds) special features in the way 

 of colour, plumage, size, or ornamentation, will be preferred and 

 chosen. Variations are thus once more produced ; since the special 

 characters of the male will be reproduced in the offspring, whilst the 

 perpetuated accumulation of such characters will in due time modify 

 the species and evolve new races therefrom. By aid of the theory of 



