KINDS OF MOTION. 



the more numerous the limbs, and the more equally they 

 are distributed on the inferior side of the body, the more 

 securely will the centre of gravity be retained within the 

 space which these feet include. In the annulose animals, 

 termed myriapocla, the feet, which are numerous, and very 

 strong in proportion to the size of the body, are so placed, 

 that the centre of gravity of the body can never fall beyond 

 the surface occupied by them ; and consequently, these ani- 

 mals may be considered as possessing, in the greatest degree 

 of perfection, the qualifications necessary for assuming and 

 maintaining a standing position. In many of the true or 

 hexapodal insects, the same provision for preserving the 

 body in a standing posture may likewise be observed. The 

 feet are well qualified, by their strength, for supporting the 

 body, and when stretched out, the space which they include 

 is, in general, many times larger than its bulk. 



Among the vertebral animals, standing is an attitude 

 practised by the Mammalia and Birds only. Among the 

 mammalia, all, except Man, stand on four feet. The body, 

 in this case, rests on an extended base ; but as the head 

 projects more or less in front of the trunk, to which the 

 fore-legs are attached, the centre of gravity falls nearer 

 these than the hind-legs. They are on that account strong- 

 er than these last, to enable them to support this addition- 

 al burden, unless in those cases where the hind-legs arc 

 used for particular kinds of motion. The head is support- 

 ed by the cervical ligaments, and by muscles, which vary 

 in strength with the weight of the head, and the actions 

 which it is required to perform. 



In Man, standing is performed on two legs only. The 

 mechanical structure of his body enables him to do this 

 without any singular exertion. The weight of his head, 

 the weakness of his arms, and the inconvenient length of 

 his legs, all prevent him from standing on his four extrrmt- 



