90 



LOCOMOTION. 



[CHAP. iv. 



fl- 



edge, the cell-membrane projecting : but it is not easy to extract a 

 cell entire, apparently on account of the delicacy of its texture, and 

 the density of the surrounding mass. 



In temporary cartilage the cells are very numerous, and situated 

 at nearly equal distances apart in the intercellular substance, which 

 is not abundant. The cells vary in shape and size, but most are 

 round or oval. Their nuclei are for the most part minutely granu- 

 lar ; the granules being, in some specimens, at a distance from one 

 another. When ossification begins, the cells, which hitherto were 

 scattered without definite arrangement, become disposed in clusters, 

 or rows, the ends of which are directed towards the ossifying part. 

 These and other changes will be described in the chapter on bone. 

 In articular cartilage the cells are oval or roundish, often dis- 

 posed in small sets of 2, 3, or 4, irregularly disseminated through 

 Fig. 14. a nearly homogeneous matrix, which is more 



abundant than in the last-named variety; 

 fig. 1 4, A. The cells measure from T^W to 

 of an inch. The nuclei are for the 

 most part small. In the interior part of the 

 cartilages of encrustation we usually find the 

 cells assuming more or less of a linear direc- 

 tion, and pointing towards the surface; fig. 14, 

 B. This arrangement is probably connected 

 with a corresponding peculiarity of texture 

 of the intercellular substance, but which it is 

 more difficult to distinguish ; for these spe- 

 cimens have a disposition to fracture in a 

 regular manner along planes vertical to the 

 surface, and the broken surface is striated in 

 the same direction. 



Near its deep or attached surface, articular 

 cartilage blends gradually with the bone it 

 invests. The cells in the neighbourhood, as 

 well as their nuclei, are surrounded with a 



sprinkling of fine opaque granules, which seem to be a rudimentary 

 deposit of bone. The true bone dips unevenly into the substance 

 of the cartilage. 



A pavement of nucleated epithelial particles has been described 

 by Henle to exist on the free surface of articular cartilage. In the 

 foetus this may be readily seen ; but in the adult we have often 

 failed to detect it, even in perfectly fresh specimens, and notwith- 

 standing great care. An irregularity of surface, like that repre-- 



Articular cartilage, from the 



