OF THE BONES. 379 



by rendering its nutrition less active than in the surrounding 

 parts. 



The articular eminences and cavities are moulded upon each 

 other. This is also the case with the cavities destined to lodge 

 soft or fluid parts, and the medullary cavities of the bones. 

 Their existence and form are greatly dependent upon those 

 parts which they contain. Thus the conformation of the 

 skull, and that of the vertebral canal depend greatly upon 

 that of the nervous centre which they lodge. The lower part 

 of the vertebral canal, when empty, is triangular, just as the 

 cotyloid cavity becomes when the head of the femur has been 

 for a long time removed from it, both these parts being formed 

 of three bony points. 



600. Be this as it may, the termination of evident growth, 

 in length and breadth, depends upon the uniting of the long 

 bones with their terminal epiphyses, and of the broad bones 

 with their marginal epiphyses, or with each other. The ter- 

 mination of the growth in thickness depends upon the cessa- 

 tion of the osseous formation at the surface of the bones. This 

 last kind of growth continues somewhat longer than the first. 



The growth of the bones nevertheless continues to take 

 place, but locally, and in an insensible manner, although some- 

 times in a manner which is still pretty sensible. 



The sensible growth depends upon a kind of juxta-position 

 at the extremities, edges, and surfaces of the bones. The in- 

 sensible growth, on the contrary, is interstitial, and depends 

 upon a true intus-susception. Striking examples of the latter 

 are seen in some morbid cases especially; in empyema, spina- 

 ventosa, &c. 



601. The growth being terminated, the bones remain the 

 seat of a habitual supply or nutrition. Deposition and ab- 

 sorption go on very slowly and in an insensible manner in 

 them in the state of health, and especially in old age. But in 

 certain cases of disease, very decided changes take place in 

 the properties of the bones, which clearly show that changes 

 not less great are operated in their composition. 



602. The facts relative to the growth and habitual nutri- 



