OF THE SPINE. 229 



weak and loose in texture, and yields to the pre- 

 vailing posture, whatever that may be. We men- 

 tion this because it is a principle important in 

 every consideration to each individual, and appli- 

 cable to both body and mind. 



The French philosophers have entertained the 

 notion that the central parts of all animals are 

 more permanent in their construction, whilst the 

 extremities are subject to variety — a theory partly 

 admitted by some eminent physiologists among 

 ourselves, and which introduces obscurity and hy- 

 potheses into one of the most remarkable proofs 

 of design. Dr. Roget, in his excellent " Bridge- 

 water Treatise," has taken up this idea. 



A spinal marrow belongs to the whole of the 

 vertebrated class of animals ; and the spinal 

 marrow must be protected by bone : accordingly, 

 as the principal use of the spine is permanent, 

 so must its form be. Yet whenever there is a 

 change in the action, or rather in the play of the 

 spine, we find the vertebrae conformable. Thus 

 the motion of a fish through the water results 

 from a lateral movement of the tail and spine ; 

 but were the constituent bones formed like those 

 of other animals of the same class, the lateral or 

 transverse processes of the vertebrae would inter- 

 fere with this motion : they are therefore removed, 

 and in order to give strength to the chain of 

 bones, the spinous processes are prolonged to- 

 wards the back, and corresponding processes 

 project towards the viscera. In the cetacea, as 

 21 



