THE CANCELLI OF BONES 121 



solely, in the bones connected directly with loco- 

 motion. And as they exist in man alone, or cer- 

 tainly present in him the highest degree of per- 

 fection, we cannot escape the conviction that they 

 relate to the kind of locomotion which he alone 

 of the whole animal series can be said to possess, 

 namely, that of walking erect, and which requires 

 in the passive and resisting organs subservient to it, 

 in order that it may be effected with ease and grace, 

 a nice combination of lightness with strength in 

 the materials. His attitude more than any other, 

 in consequence of the pillars of support being 

 arranged in vertical planes, requires the most 

 effectual means for counteracting shocks ; for in 

 all other mammals the points of support are usu- 

 ally four, and at the same time the bones of the 

 legs make angles more or less acute with each 



o O 



other, and therefore are in a condition to yield 

 readily by flexion to any increased force ; and 

 this is true of all birds and reptiles. In the ele- 

 phant, the thighbones are vertical, but they are 

 nearly at right angles with the vertebral column, 

 and the pillars of support are four instead of two. 

 From the considerations which have now been 

 offered, it is believed that the two propositions 

 which were stated at the commencement of the 

 article have been sustained, and that if any addi- 

 tional facts were necessary to show that the human 

 skeleton deviates widely in the details of its struc- 



