50 THE PHYSICAL KINSHIP 



walls of the chimney where its nest is. Its food 

 consists of insects which it gathers in the air, and 

 the few dead twigs used in making its nest are 

 nipped from the tree while the bird continues its 

 flight. The ostriches, cassowaries, and many other 

 birds, have, on the other hand, developed their legs 

 at the expense of their wings. The ostrich is said 

 to be able to outrun the horse, but it has no power 

 of flight, although it has wings and wing muscles, 

 and even the skin-folds covering the wings corre- 

 sponding to those of birds that fly. But its whole 

 flying apparatus is in ruins. The rudimentary 

 hind-toe of birds is a vestigial organ, and so are 

 the claws which appear on the thumb and first 

 finger of all young birds. So also are the rudi- 

 ments of eyes in cave crickets, fishes, and other 

 inhabitants of total darkness. The flounder and 

 other so-called flat fishes swim straight up, as 

 ordinary fishes do, when young. But as they grow 

 they incline more and more to one side, and finally 

 swim entirely on their side, the eye on the lower 

 side migrating around, and joining the other on 

 the upper side of the head. 



About the first thing a human infant does on 

 coming into the world is to prove its arboreal 

 origin by grasping and spitefully clinging to every- 

 thing that stimulates its palms. A little peeper- 

 less babe an hour old can perform feats of strength 

 with its hands and arms that many men and 

 women cannot equal. It can support the entire 

 weight of its body for several seconds hanging by 

 its hands. Dr. Robinson, an English physician, 



