DIFFICULTIES OF THE THEORY 233 





CHAPTEE VI 



DIFFICULTIES OF THE THEORY 



V 



,#^ 



DifBculties of the theory of descent with modification — Absence or rarity \^ 

 of transitional varieties — Transitions in habits of life — Diversified habits \y ,\ 

 in the same species — Species with habits widely different from those of "^ \' 

 their allies — Organs of extreme perfection — Modes of transition — Cases 

 of difficulty — Natura non facit saltum — Organs of small importance — 

 Organs not in all cases absolutely perfect — The law of Unity of Type j 

 and of the Conditions of Existence embraced by the theory of Natural 

 Selection 



LONGr before the re ader has -a rrived at. this j)art // 

 of my workj__a__crowd of difficulties will have 

 occurred to him. Some of them are so serious j. 



that to this day I can hardly reflect on them without "^.^^'j 

 being in some degree staggered; but, to the best of my iW^nL 

 judgment, the greater number are only apparent, and those -j[U/<^Aii, 

 that are real are not, I think, fatal to the theory. ' — 



These difficulties and objections may be classed under 

 the following heads: 



I First, why, if species have descended from other spe- . -j ^ 

 cies by fine gradations, do we not everywhere see innu-"^, >. 

 merable transitional fornis? Why is not all nature in oi/yi^i/i^ 

 confusion, instead of the species being, as we see them, 

 well defined? 



U; Secondly, i s_ it po ssijble_ that an ani mal having, for 

 instan ce, the structure and ha bitg--i)f ■-.a..j3at, could have 

 been formed by the modification of some other animal 

 ft w ith wide ly different habits and structure ? Can we be- 



