72 ARE THE EFFECTS OF USE INHERITED ? 



BLIND CAVE-ANIMALS. 



Weak or defective eyesight is by no means 

 rare as a spontaneous variation in animals, 

 " the great French veterinary Huzard going 

 so far as to say that a blind race [of horses] 

 could soon be formed." L-Natural selection evolves 

 blind races whenever eyes are useless or 

 disadvantageous, as with parasites. A This may 

 apparently be done independently of the effects 

 of disuse, for certain neuter ants have eyes which 

 are reduced to a more or less rudimentary 

 condition, and neuter termites are blind as well 

 as wingless. In one species of ant (Eciton vastato-r) 

 the sockets have disappeared as well as the eyes. 

 In deep caves not only would natural selection 

 cease to maintain good eyesight but it would 

 persistently favour blindness or the entire 

 removal of the eye when greatly exposed, as in 

 the cave-crab and as Dr. Ray Lankester has 



