THE PENTADACTYL TYPE. 



Medicine is a branch of natural science ; in its 

 range it dips deeply into Zoology. The anatomy of 

 man does not differ essentially from that of other mam- 

 mals. The philosophic anatomist finds interesting and 

 instructive material for reflection in the structures of 

 what are called the "inferior" animals. Indeed, it 

 has heen asserted by the most distinguished scientists 

 that the human body is bes*t understood by those who 

 have compared each part of it, so far as compari- 

 sons can be made, with homologous parts in the lower 

 animal forms. And those who are just entering upon 

 such studies will be astonished to find how closely na- 

 ture sticks to a primitive type or form. If she departs 

 from the typical formula for special or adaptive pur- 

 poses, there seems to be a disposition to return, fully 

 or in part, to the original and favorite model. This 

 tendency to adhere to a fundamental rule is exempli- 

 fied in the number of cervical vertebrae in mammals. 

 Man in his comparatively short neck has seven bones, 

 and so have the bat, the porpoise, and other almost 

 neckless creatures ; and in the long-necked giraffe, 

 camel, horse, deer, and weasel, there are but seven 

 vertebrae a typical number which prevails with won- 

 derful pertinacity, considering the scope for adaptive 

 variety in the length and functions of mammals' necks. 

 The only exceptions are in a species of sloth and the 

 tropical manati. 



Five is a common number for digital division 



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