THE 



PRINCIPAL FORMS OF THE SKELETON. 



PRINCIPLES OF OSTEOLOGY. 



The original substance of animals consists of a fluid 

 with granules and cells. In the course of development, 

 tubular tracts are formed, some of which become filled 

 with "neurine," or nervous matter; others with "mj^o- 

 nine," or muscular matter ; other portions are converted 

 into glandular substance ; and a great proportion of the 

 rest of the primordial matter forms " cellular substance." 

 This substance, in many animals, becomes hardened, in 

 certain parts of the. body, by earthy salts. When those 

 salts consist chiefly of phosphate of lime, the tissues called 

 "osteine," or bone, and "dentine," are constituted, between 

 which the chief distinction lies in the mode of arrange- 

 ment of the earthy particles, in relation to the mainte- 

 nance of a more or less free circulation of the nutrient 

 juices through such hardened or calcified tissues. In 

 bone, certain canals are left, of a caliber sufficient for the 

 passage of capillary bloodvessels through the tissue. Still 

 more minute tubes, sometimes expanding into cell-like 

 cavities, are established for the slower percolation of the 

 colorless fluid of the blood, called "plasma," or "liquor 

 In true or hard dentine provision is made, 



