POST-DARWINIAN VIEWS 65 



about an entire rejection of natural selection as a 

 factor in evolution. The tendency has been to modify 

 rather than to abandon Darwin's theory. 



Important advances have been made in cytology, or 

 the study of minute organic parts and cells by means 

 of the microscope, and in biometry, or the statistics of 

 organic changes. Many problems have been wholly or 

 partly solved; and, while new problems have emerged, 

 much progress has been achieved in accumulating data 

 for a more adequate theory of natural evolution.^ 



Darwin did not wholly reject the Lamarckian fac- 

 tor, or the inheritance of characters acquired by the 

 use and disuse of particular organs. But he gave it 

 a minor place and influence.^ Herbert Spencer, how- 

 ever, gave it the leading place ,^ although acknowledging 

 that natural selection also has a part to perform; and 

 those who have followed him in doing belated justice 

 to Lamarck's theory are called neo-Lamarckians. 

 The Lamarckian theory is certainly very plausible; 

 and in spite of the lack of adequate evidence of the 

 transmission of acquired characters, many have beHeved 

 in the Lamarckian factor, which of course depends 

 for its vahdity upon the fact of such transmission. 



August Weismann gave a new turn to the course 

 of speculation by a series of essays begun in 1881,^ in 



1 Useful accounts of post-Darwinian studies can be found in R. H. 

 Lock's Recent Progress; and V. L. Kellogg's Darwinism To-day, 

 chh. viii-xii. 2 Origin of Species, Vol. I. pp. 167-173. 



3 In First Principles; and Prins. of Biology. 



4 Subsequently translated and published by Ewd. B. Poulton and 

 others — Essays upon Heredity, etc., Oxford. His arguments are 



6 



