THE GENESIS OF SPECIES. [CHAP. 



The Darwinian theory of " Natural Selection " may be 

 shortly stated thus : i 



Every kind of animal and plant tends to increase in 

 numbers in a geometrical progression. 



Every kind of animal and plant transmits a general 

 likeness, with individual differences, to its offspring. 



Every individual may present minute variations of any 

 kind and in any direction. 



Past time has been practically infinite. 



Every individual has to maintain a very severe struggle 

 for existence, owing to the tendency to geometrical increase 

 of all kinds of animals and plants, while (from the con- 

 stancy of physical conditions acting as a continual check 

 on such increase) the total amount of animal and vegetable 

 population (man and his- agency excepted) remains almost 

 stationary from year to year. 



Thus, every variation of a sort tending to save the life 

 of the individual possessing it, or to enable it more surely 

 to propagate its kind, will in the long run be preserved, 

 and the organism that has it will transmit its favourable 

 peculiarity to some of its offspring, which peculiarity will 

 thus become intensified till it reaches the maximum degree 

 of utility. On the other hand, individuals presenting un- 

 favourable peculiarities will be ruthlessly destroyed. The 

 action of this law of " Natural Selection " may thus be well 

 represented by the convenient expression " survival of the 

 fittest." 2 



Now this conception of Mr. Darwin is perhaps the 



1 See Mr. Wallace's recent work, entitled " Contributions to the Theory 

 of Natural Selection/' where, at p. 302, it is very well and shortly 

 stated. 



2 "Natural Selection" is happily so termed by Mr. Herbert Spencer 

 in his "Principles of Biulo^y." 



