G THE OEXESIS OF SPECIES. [Chap. 



Tlie Darwinian theory of '- Xtitural Selection" may be 

 sliortly stated tlins : 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, witli individual differences, to its offspring. 



Every individual may present minute variations of any 

 kind and in any direction. 



Past time lias been practically infinite. 



Everv indiviihial has to maintain a very severe struL^'de 

 for existence, owing to the tendency to geometrical increase 

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

 stancv f)f phvsical conditions actinia as a continual ehedc 

 on such increase) the total amount of animal and vegetal >le 

 jMtpulaticm (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 t(» 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 ofts})ring, which peculiarity will 

 thus become intensifie<l 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 ^Ir. Darwin is perhaps the 



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

 (»f Natural Selection," where, at p. 302, it is viry well and shortly 

 stated. 



- "Natural Selection" i.s happily so tcrmeil by Mr. Herbert Spencer 

 in his " Principles of Biul<»;^'." 



