STRUCTURE OF BONES* 141 



of support to the softer and more active textures of 

 the body. By their means, the human frame is ena- 

 bled to unite the most finished symmetry of form 

 with the most perfect freedom of motion and secu- 

 rity to life. 



Some of the bones, such as those which compose 

 the scull and the socket for the eye, are designed 

 exclusively for the protection of important organs 

 contained within them. But by far the greater 

 number are constructed with a direct reference to 

 voluntary motion, and only incidentally serve for the 

 purposes of protection. 



In proportion to the variety of movements which 

 any piece of mechanism is required to perform, its 

 component parts must be numerous and varied. 



Considered in this light, the animal frame is the 

 most wonderful of all combinations of machinery. 

 No production of art can be compared with it for 

 the multiplicity and nicety of its evolutions, and yet 

 all these are executed simply by muscular power, 

 acting upon the bones, and changing their relative 

 positions. 



The incalculable variety of movements required 

 from man is the reason why the bones composing 

 the skeleton are so numerous, and each so admira- 

 bly connected with the others by articulations, con- 

 structed so as to admit of precisely that kind of 

 motion which the animal requires from it, and of no 

 other. The advantages of this arrangement are not 

 less obvious than admirable. Had the osseous 

 framework consisted of one entire piece, not only 

 would man and animals have been incapable of mo- 

 tion, but every external shock would have been 

 communicated undiminished to the whole system : 

 whereas, by the division of its parts, and by the in- 

 terposition of the elastic cartilages and ligaments 

 constituting the joints, free and extensive motion is 

 secured, and the impetus of every external shock is 

 deadened in its force, and diffused over the body, in 



