MAMMIFEROUS QUADRUPEDS. 339 



a tendency which is required to be counteracted by the ac- 

 tions of the muscles whicli are situated on the external side 

 of each of those angles. These muscles are tlie extensors of 

 the joints; that is, the muscles whicli tend to bring their 

 parts into a straight line. It is, in fict, by this muscular ac- 

 tion, much more than by simple rigidity, that the limb sup- 

 ports the superincumbent weight of the body. It is evi- 

 dent that greater muscular force is necessary for this purpose 

 when the joints are bent, than when they are already ex- 

 tended; and the portions of the fore legs being naturally in 

 this condition, require less power than those of the hinder 

 legs to retain them in their proper relative positions. 



The most complete instance of a vertical arrangement of 

 the bones of the extremities is seen in the Elephant; where, 

 in order to sustain the enormous weight of the body, the 

 limbs are shaped into four massive columns, of which the 

 several bones are disposed nearly in perpendicular lines. By 

 this means, the body is supported with scarcely any muscu- 

 lar effort, and the attitude of standing is, in this anim.al, a 

 state of such complete repose, that it often sleeps in that po- 

 sition. ' The elephant which was kept some years ago at the 

 Menagerie at Paris, although much enfeebled by a lingering 

 disorder, was never seen to lie down till the day on which 

 he died. When he was in the last stage of debility, what 

 seemed to give him most distress was the effort requisite to 

 support his head: and, in order to relieve the muscles of the 

 neck, which were strained in that exertion, he was in the 

 habit of extending his trunk perpendicularly to the ground, 

 by contracting all the muscular fibres which run transverse- 

 ly in that organ, and thus formed a vertical prop for the 

 head. But in almost all other quadrupeds, the mere act qf 

 standing, though a state of comparative rest, implies, for the 

 reasons already given, a degree of muscular exertion, and 

 they can enjoy complete repose only by letting the body re- 

 cline upon the ground. 



The conformation of the hind extremities, which, as we 

 have seen, is not so well calculated for the simple support ol 



