Inheritance of Variations 69 



slight that it took years to detect them with certainty. If 

 such minutely differing races have been produced from a 

 single one, the steps in the change have been at least as 

 minute as these differences. If evolution really occurs, why 

 should we not see these minute changes? 



Again, the existence of complex adaptive structures, such 

 as the eye or the ear, presents difficulties for the theory 

 of origin by extensive mutations perhaps fully as great as 

 does the existence of races differing only by minute grada- 

 tions. The difficulty here is not so readily presented in a 

 simple way, but to me it appears that thorough analysis 

 would reveal it as an insuperable one. 



Furthermore, paleontologists maintain, with practical 

 unanimity, that the study of extinct organisms shows that 

 the change in the characteristics of animals of a given stock, 

 as we pass from one geological period to another, has not 

 been by leaps, but by gradual alterations. The study of 

 paleontology is the most direct study possible of past evolu- 

 tion ; we cannot neglect its conclusions. 



On the whole then it is difficult to rest content with the 

 results of what we may call this first examination of the 

 diversities in such organisms. Shall we yield to the argu- 

 ment of Jordan, that evolution is not occurring? Or shall 

 we rather proceed to more refined studies ; to what might be 

 called investigations in the second degree? In our first 

 studies have we not possibly been overwhelmed and halted 

 by the great discovery that most of what we had thought 

 were real variations and real effects of selection were de- 

 ceptive, were mere consequences of the existence of heredi- 

 tarily diverse races, so that we have stopped before the 

 end? Shall we not next merely accept all this that has been 

 learned in the last fifteen years as a background, take a 

 new hold; select the most favorable organism possible; avoid 



