44 EVOLUTION 



of the same old materials, and — it is Nature's 

 conjuring — there is something new every 

 time. But the facts being so, it is very 

 difficult to suggest any interpretation except 

 one — that the resemblance is due to blood- 

 relationship. As Darwin said: "How inex- 

 plicable is the similar pattern of the hand of 

 a man, the foot of a dog, the wing of a bat, 

 the flipper of a seal, on the doctrine of in- 

 dependent acts of creation! How simply 

 explained on the principle of the natural 

 selection of successive slight variations 

 in the diverging descendants from a single 

 progenitor! " 



New Organs from Old. — Another set of 

 suggestive facts is found in what the compara- 

 tive anatomists have shown in regard to 

 many of the structural novelties which ap- 

 pear at point after point in the animal series, 

 that they are old organs in a new guise. The 

 poison gland of a snake is usually a specializa- 

 tion of the parotid salivary gland; the milk- 

 glands of ordinary mammals are specializa- 

 tions of the sebaceous glands of the skin, while 

 those of the egg-laying duckmole and spiny 

 ant-eater are nearer the sweat-gland type; 

 the chain of three minute bones in the mam- 

 malian ear, conveying vibrations from the 

 drum to the inner ear, is in a sense quite new, 

 and yet its links were forged long before there 



