VARIATION. 323 



" John L has a son who is normal, and a daughter, 



Jane, who was born with six fingers on each hand and six toes 

 on each foot. The sixth fingers were removed. The sixth 

 toes are not wrapped with the fifth as in her father's case, 

 but are distinct from them. The son has a son and daughter, 

 who, like himself, are normal. 



" In this, the most interesting sub-branch of the descent, 

 we see digital increase, which appeared in the first generation 

 on one limb, appearing in the second on two limbs, the hands ; 

 in the third on three limbs, the hands and one foot; in 

 the fourth on all the four limbs. There is as yet no fifth 

 generation in uninterrupted transmission of the variety. The 

 variety does not yet occur in any member of the fifth genera- 

 tion of Esther's descendants, which consists, as yet, only of 

 three boys and one girl, whose parents were normal, and of 

 two boys and two girls, whose grandparents were normal. It 

 is not known whether in the case of the great-great-grand- 

 mother, Esther P , the variety was original or inherited." * 



8G. Where there is great uniformity among the members 

 of a species, the divergences of offspring from the average 

 type are usually small; but where, among the members of a 

 species, considerable unlikenesses have once been established, 

 unlikenesses among the offspring are frequent and great. 

 Wild plants growing in their natural habitats are uniform 

 over large areas, and maintain from generation to generation 

 like structures; but when cultivation has caused appreciable 

 differences among the members of any species of plant, ex- 

 tensive and numerous deviations are apt to arise. Similarly, 

 between wild and domesticated animals of the same species, 

 we see the contrast that though the homogeneous wild race 



* This remarkable case appears to militate against the conclusion, drawn 

 a few pages back, that the increase of a peculiarity by coincidence of " spon- 

 taneous variations " in successive generations, is very improbable ; and that 

 the special superiorities of musical composers cannot have thus arisen. The 

 reply is that the extreme frequency of the occurrence among so narrow a class 

 as that of musical composers, forbids the interpretation thus suggested. 



