Chap. XV.] RECAPITULATION. 285 



the theory of creation is the occasional appearance of 

 stripes on the shoulders and legs of the several species of 

 the horse-genus and of their hybrids! How simply is 

 this fact explained if we believe that these species are all 

 descended from a striped progenitor, in the same man- 

 ner as the several domestic breeds of the pigeon are de- 

 scended from the blue and barred rock-pigeon! 



On the ordinary view of each species having been 

 independently created, why should specific characters, 

 or those by which the species of the same genus difEer 

 from each other, be more variable than generic char- 

 acters in which they all agree? Why, for instance, 

 should the colour of a flower be more likely to vary in 

 any one species of a genus, if the other species possess 

 differently coloured flowers, than if all possessed the 

 same coloured flowers? If species are only well-marked 

 varieties, of which the characters have become in a high 

 degree permanent, we can understand this fact; for they 

 have already varied since they branched off from a 

 common progenitor in certain characters, by which they 

 have come to be specifically distinct from each other; 

 therefore these same characters would be more likely 

 again to vary than the generic characters which have 

 been inherited without change for an immense period. 

 It is. inexplicable on the theory of creation why a part 

 developed in a very unusual manner in one species alone 

 of a genus, and therefore, as we may naturally infer, 

 of great importance to that species, should be eminently 

 liable to variation; but, on our view, this part has under- 

 gone, since the several species branched off from a 

 common progenitor, an unusual amount of variability 

 and modification, and therefore we might expect the 

 part generally to be still variable. But a part may be 



