II" //// 



being nearer tlio centre of gravity than tlmsc behind, have to sustain tlio 

 largest share of the weight. They ought, Consequently, t<> ! specially 

 organised as organs of support. Therefore it is that the four principal ravs 

 composing each of them shoulder, arm, ton -arm, and foot alt) lough 11 

 or disposed to bo flexed, in an inverse sense to one another, oppose to the 

 pressure of the weight of the trunk, which tends incessantly to throw them 

 down, obstacles purely mechanical, and of such energy that wo may still 

 11 in Icrstand how the body can bo sustained on the anterior limbs, if we 

 suppose all the muscular masses surrounding these bony rays removed except 

 one. 



Thus, the weight of the body is at first transmitted to the scapula through 

 the muscles that attach that bone to the trunk. It then passes to tlio 

 humerus, and from thence to the radius, to bo thrown, finally, on the different 

 pieces composing the foot. Now the humerus forming with the scapula an 

 angle which is open behind, and with the bones of the fore-arm another angle 

 open in front, the weight of the body pressing continually on these angles tends 

 to close them, and thus cause the flexion of the bony rays. But this result is 

 prevented by the combined action of two muscular powers the biceps and 

 the extensors of the fore-arm. With regard to the radius, carpus, and 

 metacarpus, owing to their vertical direction they themselves support the 

 pressure of the weight of thebody without requiring any muscular aid. But 

 the digital region, being directed obliquely forward and downward, forms, 

 with the principal metacarpal, a third angle open in front, for the sustenance 

 of which nature has given solid, inert, or contractile mechanical bands. 



The anterior limbs are also agents of transport, for they can elevate the 

 trunk by the spring of their bony rays, and fix themselves on the ground by 

 their free extremity. 



The posterior limbs arc less favourably disposed than those in front to 

 assume the function of columns of support, as their rays are for the most 

 part in a state of permanent flexion, and joined in an angular manner to one 

 another, as may be seen by glancing at the skeleton (See Figs. 1, 2, 3, 4, 

 5). It is therefore necessary that muscular agency should prevent the 

 breaking-down of these rays. Though defective as supporting columns, 

 they are nevertheless admirably designed to serve as agents of locomotion. 

 The slightest erection of these inclined rays propels the mass of the body 

 forward, and this impulsion is almost wholly transmitted to the trunk in 

 consequence of the very intimate union of the pelvis with the vertebral 

 column. 



B. PABALLEL BETWEEN THE ANTERIOR AND POSTERIOR LIMBS. After 

 what has just been said, it will bo seen that the anterior limbs arc more par- 

 ticularly destined for the support of the body, while the posterior ones more 

 especially play the part of impulsive agents in the locomotory acts. 



Notwithstanding this difference in the functions assigned them, these two 

 columns offer in their conformation such striking resemblances to each other, 

 that some authors have been inclined to consider the posterior as an exact 

 repetition of the anterior limb. The following is a brief analysis of the 

 analogies existing between them. 



At the end of the last century, Winslow and Vicq-d'Azyr, and nearer our 

 own time, Cuvier, Flourens, Paul Gcrvais. Martins, Gegcnbaur, and Lavocat, 

 have occupied themselves with the paral It -1 i si 1 1 e x isting between the anterior and 

 the posterior members. All these anatomists did not absolutely arrive at the 

 same conclusion ; for several of them, forgetting that the question should bo 

 examined in the whole animal scries, made Man alone the subject of their 



