1 88 THE HAUNTS OF LIFE 



waves of sound strike ; this is the door at which 

 they knock. But the vibrations have to be 

 conveyed to the real ear the delicate organ of 

 hearing which is safely lodged in very dense 

 bone (periotic) deeper down in the skull. Now, 

 running from the drum of the ear to the inner 

 ear, there is, in mammals, a chain of three little 

 bones called the Hammer, the Anvil, and the 

 Stirrup (Malleus, Incus, and Stapes). What 

 do these turn out to be ? Their development 

 shows that they are just transformed pieces of 

 bone which, in fishes, form part of the common- 

 place framework of the jaws. This is another 

 tell-tale evidence of the very distant aquatic 

 ancestry of mammals. 



Another very remarkable fact has to do with 

 the blood. Many of the lower animals, such as 

 sponges and jelly-fishes, sea-anemones and 

 corals, and the simpler worms, have no blood ; 

 but every one knows that this is very unusual. 

 From ringed worms to man, almost all animals 

 have blood, though, in many cases, like lobster 

 and snail, it is not very noticeable, being practi- 

 cally colourless. This blood is a very complex, 

 chemical mixture ; its watery basis contains 

 solutions of salts, sugar, proteins, and nitro- 

 genous waste-products. Every boy who has 



