CARTILAGES AND THEIR STRUCTURE. 37 



elasticity recovers their natural position, as in the nose, larynx, 

 cartilages of the ribs, he. 



Another set, in children, supplies the place of bone, until bone 

 can be formed, and affords a nidus for the osseous fibres to shoot 

 into, as in the long bones of children. 



A third set, and that the most extensive, by the smoothness 

 and lubrication of their surface, allow the bones to move readily, 

 without any abrasion, as in the cartilages of the joints. 



A fourth set supphes the oflice both of cartilage and ligament, 

 giving the elasticity of the former and the flexibility of the 

 latter, as in the bones of the spine and pelvis. 



— Next to the bones, the cartilages form the hardest tissue in 

 the body. On first inspection they do not appear to present 

 any sort of internal organization. They appear homogenous 

 in their texture and inorganic. When more carefully inspected, 

 however, and especially in the articular cartilages, a particular 

 structure is apparent. 



— According to De Lasone and Hunter, the articular cartilages 

 are composed of fibres implanted perpendicularly to the surface 

 of the bones, and parallel with each other, like the villi or threads 

 upon a piece of velvet. In this manner the cartilages covering 

 the bones forming the joints, supposed to be invested with 

 the synovial membrane, rub against each other, not upon the 

 sides, but upon the ends of the fibres, which brings the elas- 

 ticity of the latter into play. The perpendicular direction of 

 these fibres may be made apparent by maceration, or by 

 sawing down a recent bone, and splitting through its carti- 

 lage — and they were believed by Beclard, to constitute the 

 numerous free floating flocculi, which are seen on the surface 

 of cartilage in its transformations from disease. 

 — It is very probable that there is some cellular tissue in the 

 composition of cartilages : when carefully incinerated, the re- 

 mains present a cellulated appearance. Its existence is rendered 

 still more probable, from the cartilages being developed in the 

 foetus in a mould of cellular tissue ; and from fleshy granulations, 

 having been seen occasionally to spring from the surface of some 

 4 



