76 NATURAL THEOLOGY. 



that not anly the motions of the human body necessary foi 

 the ordinary offices of Ufe are performed with safety, but 

 that it is an incident hardly ever heard of that even the ges- 

 ticulations of a harlequin distort his spine. 



Upon the whole, and as a guide to those who may be 

 inclined to carry the consideration of this subject further, 

 there are three views under which the spine ought to be re- 

 garded, and in all which it cannot fail to excite our admira 

 tion. These views relate to its articulations, its hgaments, 

 and its perforations ; and to the corresponding advantages 

 which the body derives from it for action, for strength, and 

 Tor that which is essential to every part, a secure communi- 

 cation with the brain. 



The structure of the spine is not in general different in 

 different animals. In the serpent tribe, however, it is con- 

 siderably varied ; but with a strict reference to the conven- 

 lency of the animal. For whereas in quadrupeds the num- 

 ber of vertebrae is from thirty to forty, in the serpent it is 

 nearly one hundred and fifty : whereas in men and quadru- 

 peds the surfaces of the bones are flat, and these flat surfaces 

 laid one against the other, and bound tight by sinews ; in 

 the serpent, the bones play one within another, like a ball 

 and socket,^ so that they have a free motion upon one an- 

 other m every direction : that is to say, in men and quadru- 

 peds, firmness is more consulted ; in serpents, pliancy. Yet 

 even pliancy is not obtained at the expense of safety. The 

 backbone of a serpent, for coherence and flexibility, is one 

 of the most curious pieces of animal mechanism with which 

 we are acquainted. The chain of a watch — I mean the 

 chain which passes between the spring-barrel and the fu- 

 see — which aims at the same properties, is but a bungling 

 piece cf workmanship in comparison with that of which we 

 speak . 



lY. The reciprocal enlargement and contraction of the 

 chest, to allow for tlie play of the lungs, depends upon a sim 

 * Der. Phys. Thcol., p. 396. 



