DARWIN 345 



Later, in the Descent of Man^ he speaks of the 

 effects of use as probably becoming hereditary, 

 showing that he still did not consider the evi- 

 dence so convincing as that relating to disuse. 

 "The chief agents in causing organs to become 

 rudimentary seem to have been disuse, at that 

 period of life when the organ is chiefly used (and 

 this is generally during maturity), and also in- 

 heritance at a corresponding period of life." It 

 should be repeated that these decided changes of 

 opinion were, in part, a tacit acceptance of work 

 done elsewhere, especially in Germany, rather 

 than the direct outcome of Darwin's own obser- 

 vations. In part they certainly reflected his own 

 observations and maturer judgment. 



Darwin and Wallace 



Finally, we record the most striking^ of all the 

 many coincidences and independent discoveries 

 in the history of the evolution idea. Darwin's 

 long withholding of his theory from publication 

 between 1837 and 1858 came near costing him 

 his eminent claims to priority, for in the latter 

 year Alfred Russel Wallace had also reached a 

 similar theory. By the happy further coincidence 

 of a friendship which always remained of the 



11881, p. 32. 



^For details see Osborn: Impressions of Great Naturalists (vol. 

 II of this series), 1928, pp. 40-1, 77-9. 



