THE WONDER OF LIFE 587 



sting an elaborated ovipositor. The serpent's fangs are 

 folded or channelled teeth, and the reservoirs of venom are 

 but specialized salivary glands. The milk-glands of mam- 

 mals seem to have arisen from clusters of sebaceous skin- 

 glands, common to both sexes. Every schoolboy knows 

 that the elephant's trunk an extraordinary novelty in 



FIG. 92. Wing of Adelie Penguin, Pygoscelis adelise, illustrating the 

 fact that a very novel structure, a flipper, may arise by a not very 

 great transformation of an older structure a wing. (After Pycraft. ) 

 A, the entire wing covered with small flat feathers ; B, the bones of 

 the wing ; H, humerus ; B, radius ; u, ulna ; K, radiale, one of the 

 two free wrist bones ; u, ulnare, the other free wrist bone ; CMC, 

 carpometacarpus, part of wrist and palm fused ; I, thumb bone 

 fused ; II, second digit with two joints or phalanges ; III, third 

 digit with one joint (PH. I.). 



its day is just the creature's nose, and every student of 

 comparative anatomy can tell us how the hammer and 

 anvil that form part of the delicate apparatus for conveying 

 vibrations to the inner ear were once part and parcel of the 

 rougher and more commonplace mechanism of the jaws. 

 There is no doubt that to make an apparently very new 

 thing out of a really very old thing is part of Nature's magic 



