20 An Examination of Weismannism. 



all in the process of organic evolution. No matter 

 how many generations of eagles, for instance, may have 

 used their wings for purposes of flight ; and no matter 

 how great an increase of muscularity, of endurance., and 

 of skill, may thus have been secured to each genera- 

 tion of eagles as the result of individual exercise ; 

 all these advantages are entirely lost to progeny, and 

 young eagles have ever to begin their lives with no 

 more benefit bequeathed by the activity of their 

 ancestors than if those ancestors had all been barn- 

 door fowls. The only material which is of any count 

 as regards the species, or with reference to the process 

 of evolution., are fortuitous variations of the congenital 

 kind. Among all the numberless congenital varia- 

 tions; within narrow limits, which are perpetually 

 occurring in each generation of eagles, some will have 

 reference to the wings ; and although these will be 

 fortuitous, or occurring indiscriminately in all direc- 

 tions, a few of them will now and then be in the 

 direction of increased muscularity, others in the 

 direction of increased endurance, others in the direc- 

 tion of increased skill, and so on. Now each of these 

 fortuitous variations, which happens also to be a 

 beneficial variation, will be favoured by natural 

 selection ; and, because it likewise happens to be a 

 congenital variation, will be perpetuated by heredity. 

 In the course of time, other congenital variations will 

 happen to arise in the same directions ; these will be 

 added by natural selection to the advantage already 

 gained, and so on, till, after hundreds and thousands of 

 generations, the wings of eagles have become evolved 

 into the marvellous structures which they now present. 

 Such being the theory of natural selection when 



