CHAPTER VI 



DIFFICULTIES AND OBJECTIONS 



Difficulty as to smallness of variations — As to the right variations occur- 

 ring when required — The beginnings of important organs — The mam- 

 mary glands — The eyes of flatfish — Origin of the eye — Useless or 

 non-adaptive characters — Recent extension of the region of utility in 

 plants — The same in animals — Uses of tails— Of the horns of deer — 

 Of the scale-ornamentation of reptiles — Instability of non-adaptive 

 characters — Delboeuf's law — No "specific" character proved to be 

 useless — The swamping effects of intercrossing — Isolation as prevent- 

 ing intercrossing — Gulick on the effects of isolation — Cases in which 

 isolation is ineffective. 



In the present chapter I propose to discuss the more obvious 

 and often repeated objections to Darwin's theory, and to show 

 how far they affect its character as a true and sufficient 

 explanation of the origin of species. The more recondite 

 difficulties, affecting such fundamental questions as the causes 

 and laws of variability, will be left for a future chapter, after 

 we have become better acquainted with the applications of the 

 theory to the more important adaptations and correlations of 

 animal and plant life. 



One of the earliest and most often repeated objections was, 

 that it was difficult " to imagine a reason why variations tend- 

 ing in an infinitesimal degree in any special direction should 

 be preserved," or to believe that the complex adaptation of 

 living organisms could have been produced " by infinitesimal 

 beginnings." Now this term "infinitesimal," used by a well- 

 known early critic of the Origin of Species, was never made use 

 of by Darwin himself, who spoke only of variations being 

 "slight," and of the "small amount" of the variations that might 

 be selected. Even in using these terms he undoubtedly afforded 



