The science of life : fully illustrated in tone and line and including many diagrams

THE EVIDENCE FROM PLANTSAND ANIMA'L STRUCTURE

as their general anatomy indicates, snakes have evolved from lizards, these vestiges make sense ; without the background of Evolution, they are inexplicable.

The Duckbill Platypus has no teeth ; like a bird, it uses a horny bill instead. But it is a mammal, and on evolutionary principles must have descended from toothed forbears. We look for evidence on this point—and there the evidence is, carried about by the baby Platypus in the shape of teeth which, though they are complete with dentine and enamel, never cut the gum. They have no function whatever, save that of reassuring the Evolutionist : and the same is true of the whalebone whales, for here also the embryo develops teeth and then changes its mind and absorbs them again, all before it is born.

The vestiges of toes preserved to us in the horse’s splint-bones have no sense save an evolutionary one ; and here the fossil record clinches the matter by showing that this sense is the true sense. ;

‘In the common Vapourer moth, which of recent years has become such a pest to trees in London parks, the females are wingless. Where they burst out of their cocoons, there they stay, and are there sought out and fertilized by the winged males. Most moths, of course, are winged in both sexes ; thus on the theory of Evolution we should expect that the wingless female Vapourer had arisen from winged ancestors. That she has done so is shown by the fact that she still bears the vestiges of wings—mere buds, wholly useless for any purpose ; and, interestingly enough, in the chrysalis stage the wing-rudiments are actually larger than in the adult moth.

Another very pretty example of a vestigial organ is to be seen in the African Swallowtail butterfly, Papilio

mimic other butterflies which happen to enjoy immunity from attack by most enemies.

dardanus. The “ tails’? of Swallowtails are prolongations of the hind wings ; and in order to make room for these during the resting stage between caterpillar and butterfly, their chrysalis-cases possess special little pockets into which the tailrudiments project. Now, Papilio

dardanus differs from most Swallowtails in being tailless in the female sex; for the females, in shape, colour and_ pattern,

Fig. 135. Another example of a Vestigial Hind-limb in vertebrates. Above, a view of the region of ils vent som beneath. On the right the surface is shown, with a singe Pe claw, sole external remnant of the hind-limb. On ue he Ee is drawn, with the vestigial skeleton of the epeeve eae er li lying outside the ribs, and not connected with the :

Below, an Anaconda.

But the chrysalis-cases of the females possess tail-pockets just like those of the males, although they are obviously useless and not to

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