190 



OSSEOUS SYSTEM. 



[SECT. 102. 



Fig. 84. 



two rows, and, when they have grown further, give rise to the 



above-mentioned oblong group, 

 whilst in others they form a 

 more spherical mass. During 

 these changes, the original cells 

 (primitive mother capsules), some- 

 times, through coalescence of their 

 outer cell-membranes with the 

 surrounding matrix, cease to exist 

 as peculiar structures, sometimes 

 not ; and the same holds good 

 with those of later generations. 

 The rounded groups of cells being 

 smaller, usually retain their ori- 

 ginal inclosing capsule, which, 

 now greatly dilated, may be 

 recognised as a contour line 

 surrounding them ; but when the 

 cells are arranged in rows, the 

 membrane of the original cap- 

 sule is so blended with the ad- 

 joining matrix, as to be no longer 

 distinguishable. The entire layer, 

 which the above-described, en- 

 larged -and multiplying cells, occu- 

 py, varies in thickness in different 

 cartilages. It is thin around the 

 points of ossification of the epi- 

 physes and short bones ; J to ^ 

 a line upon the diaphyses. By 

 its yellowish translucent colour, 

 and its striated, apparently fibrous 

 matrix {Brandt saw this also 

 homogeneous), it is everywhere 

 distinguished from the other parts of the cartilage which are, as 

 usual, bluish-white, with homogeneous or granular matrix. 



The appearance and progress of vessels in ossifying cartilages is 

 an interesting phenomenon. They are found, in many places, 

 from the middle of foetal life onwards, preceding, for a shorter or 

 longer time, the appearance of the points of ossification, and ac- 

 company these in their growth. I have observed them, even, in 

 the articular cartilage of the epiphyses of the long bones of a 



Perpendicular section from the border of 

 ossification of the diaphysis of the temur of a 

 child two weeks old ; magnified 20 times. 

 a. Cartilage, the cells of which, the nearer 

 they approximate to the border of ossifica- 

 tion are arranged in longer longitudinal 

 rows. 6. Border of ossification, the dark 

 stripes indicate the ossification taking place 

 in the intercellular substance, the clear lines, 

 the cartilage-cells which ossify at a later pe- 

 riod, c. Compact bone near the border of 

 ossification, d. Substantia spongiosa with 

 medullary spaces, e. produced by the absorp- 

 tion of developed osseous substance, whose 

 contents are not exhibited. 



