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 develop- 

 ment shows that they are just transformed 

 pieces of bone which, in fishes, form part of 

 the commonplace 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 practically colourless. This blood is a 

 very complex, chemical mixture; its watery 

 basis contains solutions of salts, sugar, pro- 

 teins, and nitrogenous waste-products. Every 



