112 THE GENESIS OF SPECIES. [Chap. 



witli such facets is denied by pure Darwinians, but it is 

 contended in this work, though not in this chapter, tliat 

 something nuiy also be said for their existence. 



Tiie considerations brought forward in the last two 

 chapters, namely, the dilliculties with regard to incipient 

 and closely-similar structures respectively, together with 

 paleonlological considerations to be noticed later, appear 

 to point strongly in the direction of sudden and consider- 

 able changes. This is notably the case as regards the 

 young oysters already mentioned, which were taken from 

 the shores of England and placed in the Mediterranean, 

 and at once altered their mode of growth and formed 

 prominent diverging rays, like those of the proper Mediter- 

 ranean oyster^ as also the twenty-nine kinds of American 

 trees, all differing from their nearest European allies siiui- 

 larlxj — " leaves less toothed, buds and seeds smaller, fewer 

 branchlets," etc. To these may be added other facts given 

 by Mr. Darwin. Thus he says, that " climate, to a certain 

 extent, directly modifies the form of dogs." ^ 



The licv. U. Everett found (hat setters at Delhi, though 

 most caiefully paired, yet had young with " nostiils more 

 contracted, noses more pointed, size inferior, and limbs 

 more slender." Again, cats at Mond)as, on the coast of 

 Africa, have short, stilf hau'S, instead of fur; and a cat at 

 Algoa Bay, when left only eight weeks at Mombas, " un- 

 derwent a complete metamorphosis, having parted with its 

 sandy-colored fur." ^ The conditions of life seem to pro- 

 duce a considerable eftect on horses, and instances are 

 given by Mr. Darwin of pony breeds* having independent- 

 ly arisen in dilferent parts of the world, possessing a cer- 

 tain similarity in their physical conditions. Also changes 

 due to climate may be brought about at once in a second 

 generation, though no appreciable modification is shown 



' "Animals and Plants under Domestication," vol. i., p. 37. 

 « Ibid., p. 47. ^ Ibid., p. 52. 



