74 APPENDIX. 



increasing distinctness and volume with every genera- 

 tion, and also in an increasing number of individuals ? 

 The mere displacement of the zero-point of useful 

 variations alone must produce this effect, especially 

 when it is supported by germinal selection. It is im- 

 possible, indeed, to see how considerable, that is per- 

 ceptible, deviations could arise at all on the path of 

 phyletic development if in each generation a large 

 number of individuals always possessed the useful, 

 that is, the phyletic variations? In fact, by the as- 

 sumption itself, the difference between useful and 

 less useful variations is merely one of degree, and 

 that a slight one. 



Hence, as I before remarked at page 31, I see no 

 reason for assuming two kinds of hereditary variations, 

 distinct as to their origin, such as Scott and the other 

 palaeontologists mentioned have been led to adopt, al- 

 though with the utmost caution. I believe there is 

 only one kind of variation proceeding from the germ, 

 and that these germinal variations play quite different 

 roles according as they lie or do not lie on the path 

 of adaptive transformation of the species, and conse- 

 quently are or are not favored by germinal selection. 

 To repeat what I have said in the footnote to page 31 

 only a relatively small portion of the numberless in- 

 dividual variations lie on the path of phyletic ad- 

 vancement and so mark out under the guidance of 

 germinal selection the way of further development ; 

 and hence it would be quite possible to distinguish 

 continuous, definitely directed variations from such 

 as fluctuate hither and thither with no uniformity in 

 the course of generations. The origin of the two is 

 the same ; they bear in them nothing that distinguishes 

 the one from the other, and their success alone, that 



