324 THE CAUSES OF THE si 



skeleton that of a kind of lemur you see he 

 has just the same bones ; and if I were to make a 

 transverse section of it, it would be just the same 

 again. In your mind's eye turn him round, so as 

 to put his backbone in a position inclined obliquely 

 upwards and forwards, just as in the next three 

 diagrams, which represent the skeletons of an 

 orang, a chimpanzee, and a gorilla, and you find 

 you have no trouble in identifying the bones 

 throughout ; and lastly turn to the end of the 

 series, the diagram representing a man's skeleton, 

 and still you find no great structural feature 

 essentially altered. There are the same bones in 

 the same relations. From the horse we pass on 

 and on, with gradual steps until we arrive at last 

 at the highest known forms. On the other hand, 

 take the other line of diagrams, and pass from the 

 horse downwards in the scale to this fish ; and 

 still, though the modifications are vastly greater, 

 the essential framework of the organisation 

 remains unchanged. Here, for instance, is a 

 porpoise : here is its strong backbone, with the 

 cavity running through it, which contains the 

 spinal cord ; here are the ribs, here the shoulder- 

 blade ; here is the little short upper-arm bone, 

 here are the two forearm bones, the wrist-bone, 

 and the finger-bones. 



Strange, is it not, that the porpoise should have 

 in this queer-looking affair its flapper (as it is 

 called), the same fundamental elements as the 



