CH. V.] 



CARTILAGE 



51 



are larger, more angular, and collected into larger groups than in 

 articular cartilage. Under the perichondrium, a fibrous membrane 

 which surrounds the rod of carti- 

 lage, the cells are flattened and 

 lie parallel to the surface ; in the 

 deeper parts they are irregularly 

 arranged ; they frequently contain 

 fat (see fig. 77). > 



The hyaline cartilages of the 

 nose, larynx, and trachea (fig. 78) 

 resemble costal cartilage. 



Hyaline cartilage in many 

 situations (costal, laryngeal, tra- 

 cheal) shows a tendency to become calcified late in life. 



On boiling, the ground-substance of cartilage yields a material 

 called chondrin. This resembles gelatin very closely, and the differ- 

 ences in its reactions are due to the fact that chondrin is not a 

 chemical individual, but a mixture of gelatin with varying amounts 

 of mucin-like substances. 



FIG. 76. Vertical section of articular cartilage ; 

 a, cell-groups arranged parallel to surface ; 

 D, cell-groups irregularly arranged ; c, cell- 

 groups arranged perpendicularly to surface. 



Flu. 77. Costal cartilage from an adult 

 dog, showing fat-globules in the 

 cartilage-cells. (Cadiat.) 



FIG. 



. 78. Ordinary hyaline cartilage from 

 trachea of a child. The cartilage- 

 cells are enclosed singly or in pairs 

 in a capsule of hyaline substance, 

 x 150 diams. (Klein and Noble 

 Smith.) 



White Pibro-Cartilage occurs 



1. As inter-articular fibro-cartilage e.g., the semilunar cartilages 

 of the knee-joint. 



2. As circumferential or marginal cartilage, as on the edges of the 

 acetabulum and glenoid cavity. 



3. As connecting cartilage e.g., the inter-vertebral discs. 



. In the sheaths of tendons and sometimes in their substance. In 



