3 6 TEXT-BOOK OF PHYSIOLOGY 



2. White fibro-cartUage, the ground substance of which is pervaded by white 

 fibers, arranged in bundles or layers, between which are scattered the 

 usual encapsulated cells. (See Fig. io,c.) White fibro-cartilage is 

 tough, resistant, but flexible, and is found in joints where strength and 

 fixedness are required. Hence it is present between the vertebrae, 

 forming the intervertebral discs, between the condyle of the lower jaw 

 and the glenoid fossa, in the knee-joint, around the margins of the jomt 

 cavities, etc. In these situations it assists in maintaining the apposition 

 of the bones, in giving a certain degree of mobility to the joints, and in 

 diminishing the effects of shock and pressure imparted to the bones. 



-> . ~-~' -~ ^ 



ABC 



FIG. 10. THE THREE TYPES OF CARTILAGE: A, HYALINE; B, ELASTIC; C, FIBROUS. (Rod- 

 each), a, b, Outer and inner layers of perichondrium; c, young cartilage cells; d, older cartilage 

 cells; e, f, capsule; g, lacuna. 



3. Yellow fibro-cartilage, the ground substance of which is pervaded by 

 opaque, yellow elastic fibers, which form, by the interlacing of their 

 branches, a complicated network, in the meshes of which are to be found 

 the usual corpuscles. (See Fig. IO,B.) As these fibers are elastic, they 

 impart to the cartilage a very considerable degree of elasticity. Yellow 

 fibro-cartilage is well adapted, therefore, for entering into the formation of 

 the external ear, epiglottis, Eustachian tube, etc. structures which 

 require for their functional activity a certain degree of flexibility and 

 elasticity. 



Osseous Tissue. Osseous tissue, as distinguished from bone, is a 

 member of the connective-tissue group, the ground substance of which is 

 permeated with insoluble lime salts, of which the phosphate and carbonate 

 are the most abundant. Immersed in dilute solutions of hydrochloric acid, 

 they can be converted into soluble salts and dissolved out. The osseous 

 matrix left behind is soft and pliable. When boiled, it yields gelatin. 



A thin, transverse section of a decalcified bone, when examined micro- 

 scopically, reveals a number of small, round, or oval openings, which repre- 

 sent transverse sections of canals which run through the bone, for the most 

 part in a longitudinal direction, though frequently anastomosing with one 

 another. These so-called Haversian canals in the living state contain blood- 

 vessels and lymphatics. (See Fig. n.) 



