474 PRIMARY FACTORS OF ORGANIC EVOLUTION. 



distinguishing it widely from the inorganic energies. 

 In considering the dynamics of organic evolution, 

 it will be convenient to commence by considering the 

 claims of natural selection to include the energy which 

 underlies the process. That natural selection cannot 

 be the cause of the origin of new characters, or varia- 

 tion, was asserted by Darwin ; l and this opinion is 

 supported by the following weighty considerations : 



1. A selection cannot be the cause of those alterna- 

 tives from which it selects. The alternatives must be 

 presented before the selection can commence. 



2. Since the number of variations possible to or- 

 ganisms is very great, the probability of the admirably 

 adaptive structures which characterize the latter hav- 

 ing arisen by chance, is extremely small. 



3. In order that a variation of structure shall sur- 

 vive, it is necessary that it shall appear simultaneously 

 in two individuals of opposite sex. But if the chance 

 of its appearing in one individual is very small, the 

 chance of its appearing in two individuals is very much 

 smaller. But even this concurrence of chances would 

 not be sufficient to secure its survival, since it would 

 be immediately bred out by the immensely preponder- 

 ant number of individuals which should not possess 

 the variation. 



4. Finally, the characters which define the organic 

 types, so far as they are disclosed by paleontology, 

 have commenced as minute buds or rudiments, of no 

 value whatever in the struggle for existence. Natural 

 selection can only effect the survival of characters when 

 they have attained some functional value. 



In order to secure the survival of a new character, 

 that is, of a new type of organism, it is necessary that 



1 Origin of Species, Ed. 1872, p. 65. 



