THE OSSEOUS SYSTEM. 319 



as 60, according to Donders). The most remarkable charac- 

 teristic of the elementary tissue of the costal cartilage, is 

 the large quantity of fat contained in it. In the adult, 

 every cell, excepting the p . 124 



most superficial, con- r 



tains, larger or smaller / , 4 



(from 0-0016— 0-008"'), ,' f 



sometimes spherical, /'y^^^^W 



sometimes more irregu- ' 



lar fat-drops, which fre- 

 quently so surround the 

 nucleus as entirely to 

 conceal it from view 

 (fig. 124, a b), whence 

 it has been assumed, 

 though not quite cor- 

 rectly, that the fat is 



seated in the latter. The cartilage on the greater cornu of 

 the os hyoides, and between the body and the greater cornu, 

 and the inconstant cartilaginous appendage to the styloid 

 process, differ in no respect from costal cartilage, only that 

 the cartilage cells in those instances do not always contain 

 large fat-globules. 



The costal cartilages frequently become ossified in old age ; 

 but this ossification, as Avell as the fibrillation of the matrix, 

 must not be regarded as a normal process, nor be placed in 

 the same category with the usual kind of ossification. The 

 ossification is sometimes more limited, sometimes more ex- 

 tensive. In the former case, it does not proceed further 

 than to the incrustation of the cartilage-cells, and of the 

 matrix in which they are lodged, which has become fibrous ; 

 in the latter, and frequently also in the former, the ossification 

 is preceded by the formation of hollow spaces in the cartilage, 

 in which is deposited a cartilage-marrow, containing vessels, 

 which are connected, in part with those of the perichondrium, 



Fig. 124. Cartilage cells of Man, x 350 diam.: a, parent cell with three secondary 

 cells containing oil, from a costal cartilage; b, two cells from the same situation, in 

 which the glohule of oil is surrounded by a pale border ; c, two cells with thickened 

 walls from the cartilage of the greater cornu of the os hyoides, which together with 

 the globule of oil also contain a distinct nucleus. 



