352 SPECIAL HISTOLOGY. 



normally in certain situations (on the appearance of the first 

 points of ossification of the embryo, those of the ossicula auditus, 

 &c), still, this does not prove that the vessels when existing 

 have no concern in the processes adverted to; and consequently 

 it cannot be admitted, as lately supposed by H. Meyer, that 

 they are to be regarded in the light of accidental productions, 

 and as standing in no necessary relation with the development 

 of the bone. 



§ 104. 



Ossification of the Cartilage. — The ossification of the matrix 

 generally precedes in some degree that of the cartilage- cells; 

 and, under normal conditions, is primarily effected by a 

 granular deposition of calcareous salts (calcareous granules as 

 they are termed). Where the cells are disposed in rows, at 

 the ossifying border, this deposition of earthy matter always 

 proceeds in the fibrous substance between the rows of cells, 

 forming processes, which, in a longitudinal section, assume the 

 appearance of pointed teeth, and surround the lowest portions 

 of the rows of cells like short tubes. The same disposition, 

 essentially, is also manifested in other situations, where the 

 cartilage-cells constitute more rounded groups, only, that in 

 this case the ossifying matrix surrounds them more in a 

 reticular manner. The calcareous granules or particles, the 

 first visible deposit of the earthy salts of bones, are of a rounded 

 angular figure, white by reflected, opaque by transmitted light, 

 easily dissolved w r ith effervescence in acids, and differing in 

 size in different bones, from immeasurable minuteness up to 

 0001'", or even 002"; their size, however, does not appear 

 to be regulated by period or situation, although there is no 

 doubt that they are frequently, in one place, of uniform minute- 

 ness, and in others uniformly of coarser character, but rather by 

 some change occurriug in the supply of plastic material to the 

 ossifying border. If this earthy deposit be traced in micros- 

 copical sections, from the margin of the ossification into the 

 interior of the young bone, it will be apparent, that it is 

 to it, for a certain distance, although with diminishing distinct- 

 ness, that the granular and opaque aspect of the margin itself 

 is due; the substance gradually becomes more homogeneous, 

 clearer and more transparent, ultimately acquiring the aspect 



