206 DARWINISM AND HUMAN LIFE 



having no functional value. At a later stage in 

 the history of such a form these correlated growths 

 may acquire value and become the subject of 

 selection." 



(d) Among palaeontologists, too, there are some, 

 like Prof. H. F. Osborn, who make out a strong 

 case for the origin of new characters by definite 

 progressive variation, and " not by the selection 

 of the fit from the fortuitous." In other words, 

 many palaeontologists claim that indefinite varia- 

 tions off the main line are absent, so far as the 

 rock-record tells. 



" The law of gradual appearance or origin of 

 many new characters in definite or determinate 

 directions from the very beginning I regard as 

 the grandest contribution which palaeontology has 

 made to evolution." 2 We must attach great 

 importance to this expression of opinion, for it is 

 shared by many who, like Prof. Osborn, have 

 given their life to studying the actual history ; but 

 it must be borne in mind that highly specialised 

 types, like Ammonites and mammals, may be like 

 well-pruned trees they may have been selected 

 through long periods into lines of determinate 

 variation. The power of divergent idiosyncrasy 

 may have been pruned out of them. 



After referring to the work of Waagen on 

 Ammonites and his own work on mammals (e.g. 

 their teeth), Prof. H. F. Osborn says : " The law 

 of gradual change in certain determinate, definite, 

 and, at least in some cases, adaptive directions, 

 through very long periods of time, and the absence 



1 Nature (July 1, 1909), p. 10. 



2 " Darwin and Palaeontology," by H. F. Osborn, in " Fifty 

 Years of Darwinism " (1909). 



