DEVELOPMENT OF CARTILAGES. 253 



my own. Possessed of no animal sensibility in the natural 

 state, it is doubtful whether they ever have it, or can inflame, 

 as the pains in inflammations of the joints may arise from the 

 synovial membranes. 



In the embryo, the osseous and cartilaginous systems are 

 confounded, so as to present a homogeneous, mucous or pulpy 

 appearance; they only become distinct by the deposite of cal- 

 careous matter in the bones: when the latter. are somewhat ad- 

 vanced, the cartilages, which are to remain such, have also 

 additional consistence, and more of a proper cartilaginous look; 

 but the appearance is generally unsatisfactory, by which one 

 can learn to distinguish the cartilages that are to remain such, 

 from the cartilaginous rudiments of the bones. The following 

 circumstance, however, is pointed out by Bichat: in the carti- 

 lages of ossification, there is a vascular net-work between the 

 cartilage and the ossification which has occurred, and owing 

 to the interposition of it, the two may be easily separated. 

 But, in the permanent cartilage, this net-work does not exist 

 between the proximate surfaces, consequently they adhere 

 with a tenacity not admitting of a rigid separation from one 

 another. 



As the individual reaches adult age, the cartilages acquire 

 the strength, whiteness, and great elasticity which distinguish 

 them. In old age they become yellowish, more brittle, and 

 are, as said, generally disposed to ossify. Those of the ribs 

 and larynx are frequently ossified at forty years of age. The 

 ossification of those of the moveable joints is rare, and begins 

 at a more advanced period. In the first two it begins com- 

 monly near their centre, and in the last on the surface. 



ACCIDENTAL DEVELOPMENT OF CARTILAGES. 



The unnatural development of cartilages, in the tissues and 

 organs of the body, to which they are very slightly allied in 

 their nature, is a circumstance by no means uncommon, and 

 is met with annually, in most of its varieties, in our dissecting- 

 rooms. As there is a great disposition in such cartilages to 

 ossify, they are presented in the several gradations from a soft 

 gelatinous body to that of perfect bone. They occur in the 



VOL. L 22 



