104 NO STRUGGLE NO SELECTION 



variations appear in many individuals, and may after 

 many generations reappear in the same family, not 

 however by inheritance, but owing to their belong- 

 ing to the variability of the species. The fugitive 

 and unstable nature of individual variations is strikingly 

 demonstrated by the fact that they are liable to fall 

 off in a body from individuals of a breed, even when 

 they have been accumulated by man's action for many 

 generations, to give place to generic characters, whose 

 tendency to reappear has been transmitted by an 

 unbroken inheritance through uncounted generations. 



" Eeversion " is not a happy word by which to 

 express the appearance in individuals of a species of 

 old generic markings. The force comes down the 

 stream from above, and does not ascend from below. 

 The individual does not revert, but is overcome 

 by the pressure of generic transmission. Of such a 

 nature are the following cases instanced by Darwin. 

 When a spinal stripe is found in horses of the most 

 distinct breeds ; when transverse bars are found in 

 duns, mouse-duns, and more rarely in chestnut horses ; 

 when the foal of an ass has very distinct burs on its 

 legs, like those on the legs of a zebra ; when the stripe 

 on the shoulder of an ass is sometimes double and is 

 very variable in length and outline, we have cases of 

 the usually repressed generic characters forcing their 

 way through the opposition of specific characters, and 

 making themselves visible. 



The paragraph upon which 1 have commented in such 

 detail, taken in connection with the examples which lie 



