34 THE GENESIS OF SPECIES. [CHAP. 



so candid and careful as the author of the theory in ques- 

 tion, will feel obliged, rather than the reverse, by the sug- 

 gestion of all the doubts and difficulties which can be 

 brought against it. 



What is to be brought forward may be summed up as 

 follows : 



That " Natural Selection " is incompetent to account 

 for the incipient Stages of useful structures. 



That it does not harmonize with the coexistence of 

 closely-similar structures of diverse origin. 



That there are grounds for thinking that specific dif- 

 ferences may be developed suddenly instead of gradually. 



That the opinion that species have definite though very 

 different limits to their variability is still tenable. 



That certain fossil transitional forms are absent, which 

 might have been expected to be present. 



That some facts of geographical distribution supple- 

 ment other difficulties. 



That the objection drawn from the physiological dif- 

 ference between " species " and " races " still exists unre- 

 futed. 



That there are many remarkable phenomena in organic 

 forms upon which " Natural Selection " throws no light 

 whatever, but the explanations of which, if they could be 

 attained, might throw light upon specific origination. 



Besides these objections to the sufficiency of " Natural 

 Selection," others may be brought against the hypothesis 

 of " Pangenesis," which, professing as it does to explain 

 great difficulties, seems to do so by presenting others not 

 less great almost to be the explanation of obscurum per 

 obscurius. 



