MISPLACED RELIANCE. 147 



and our continued adaptation to the changing 

 conditions of a progressive civilization. 



It is curiously uncertain and irregular in its 

 action. It diminishes or abolishes some structures 

 (such as jaws or eyes) without correspondingly 

 diminishing or abolishing other equally disused 

 and closely related parts (such as teeth, or eye- 

 stalks). It thickens ducks' leg-bones while allow- 

 ing them to shorten. It shortens the disused 

 wing-bones of ducks and the leg-bones of rabbits 

 while allowing them to thicken ; and yet in other 

 cases it greatly reduces the thickness of bones 

 without shortening them. It transmits tameness 

 most powerfully in an animal which usually 

 cannot acquire it. It aids in webbing the feet of 

 water-dogs, but fails to web the feet of the water- 

 hen or to remove the web in the feet of upland 

 geese. 1 It allows the disused fibula to retain a 



1 Professor Romanes had casts made of the feet of upland geese, 

 and could not detect any diminution as compared with the web of 

 other geese in relation to the toes. 



L 2 



