THE CONNECTIVE TISSUES. 45 



wide distribution, occurring as the articular cartilage of bones, costal 

 cartilages, the larger cartilages of the larynx, trachea, or bronchi, 

 nose, Eustachian tube, etc. ; in the embryo the entire skeleton, with 

 the exception of the vault of the cranium, the bones of the face, and 

 the greater part of the lower jaw, is mapped out by primary hyaline 

 cartilage. 



The homogeneity of the hyaline matrix is only apparent, since, 

 as long ago pointed out by Leidy, the intercellular substance may be 

 resolved into bundles of fibrous connective tissue, which, however, 

 are so closely united and intimately blended by the cementing ground- 

 substance that the presence of the fibres is, ordinarily, not evident. 

 After prolonged boiling, cartilage matrix yields chondrin. 



Embedded within the hyaline matrix lie the cartilage >cejls ; 

 these are irregularly oval or angular nucleated protoplasmic bodies, 

 which, during life, probably fill the spaces, or lacunae, which they 

 occupy. In adult tissue usually two or 

 more cells share the same compartment, 

 the original occupant of the space having 

 undergone division, so that two, four, or 

 even more daughter- cells form a single 

 group. The matrix immediately sur- 

 rounding the lacuna is specialized as a 

 layer of different density, thereby as- 

 suming the appearance of a distinct limit- 

 ing membrane, described as the capsule. 

 A further differentiation of the ground- 

 substance is seen in the greater intensity 

 with which the more recently formed 

 matrix enveloping the cells stains; such re- 

 sulting figures constitute the cell-areas. 

 It is to be remembered that the cartilage- 

 cells are but connective-tissue cells, and 

 that the lacunae correspond to the lymph- 

 or cell-spaces found in other dense 

 connective tissues. Since it is usual to 

 find these cell-spaces in communication 

 through minute channels, or canaliculi, 

 their absence and the apparent isolation 



of the lacunae in cartilage are to be regarded as deviations from the 

 typical arrangement ; among some lower forms, however, such a 

 communication exists^ the minute canaliculi passing between the 

 neighboring lacunae. 



The free surface of the cartilage is covered by an envelope of dense 

 connective tissue, the perichondrium ; this consists of an external 



Hyaline cartilage with perichon- 

 drium (j>) attached : y, zone of 

 youngest cartilage-cells; m, hyaline 

 matrix enclosing the lacunae contain- 

 ing the cartilage-cells ; /, space from 

 which the cell has been lost. 



