

THE TISSUES 31 



homogeneous, translucent appearance, and a tough and elastic 

 consistence, and cuts like cheese with the knife (fig. 11). 



The formed material of cartilage is not a special substance, but 

 a mixture of chondroitin-sulphuric acid with collagen in com- 

 bination with proteins. Chondroitin when decomposed yields 

 glucosamine, a sugar-like substance containing nitrogen, and 

 glycuronic acid, another substance closely related to the sugars 

 (p. 23). 



Cartilage is surrounded by a fibrous membrane, the peri- 

 chondrium, and frequently no 

 hard and fast line of demarca- 

 tion can be made out between 

 them. The fibrous tissue gradu- 

 ally becomes less fibrillated 

 the cells become less elongated 

 and more oval, as if the inter- 

 fibrillar substance increased in 

 amount and became of the same tS-.j ' 

 refractive index as the fibres. 

 During old age a fibrillation of 

 the homogeneous-looking carti- 

 lage is brought out, especially > > ^ 



in COStal Cartilage, by the de- FlG - H. Hyaline Cartilage covered 

 position Of lime Salts in the by perichondrium. 



matrix, between the fibres. It was long ago shown that in 

 inflammation of cartilage this fibrillation appears; and by 

 digesting in baryta water, a similar structure may be brought 

 out. The close connection of cartilage with fibrous tissue is 

 thus clearly demonstrated. 



Such homogeneous or hyaline cartilage precedes most of the 

 bones in the embryo, and covers the ends of the long bones in 

 the adult (articular cartilage), forms the framework of the 

 larynx and trachea, and constitutes the costal cartilages. 



(2) Elastic FUro-Cartilage. In certain situations e.g. in the 

 external ear a specially elastic form of cartilage is developed, 

 elastic fibres appearing in the cartilaginous matrix, and forming 

 a network through it. 



(3) White Fibro-Cartilage. In other situations e.g. the 

 intervertebral discs a combination of the binding action of 

 fibrous tissue with the padding action of cartilage is required ; 



