816 SPECIAL HISTOLOGY. 



and a wall composed of more or less developed connective tissue, and 

 subsequently also of elastic fibrils. As concerns the vessels themselves, 

 I have sometimes found, in a canal, only one large vessel (frequently 

 very distinctly arterial, with muscular walls), sometimes two such, some- 

 times capillaries in various numbers, but I am unable to explain how the 

 circulation is carried on in these vessels. There must either be anasto- 

 moses between the vessels of different canals, or if the latter be really 

 closed, arteries and veins both probably exist in one and the same canal. 

 The object of these vessels of cartilage appears to be one of a double cha- 

 racter; in the first place, to convey the materials requisite for its growth 

 and further development; and secondly, to promote the ossification. 

 The former of these functions is very manifestly carried out in the thick 

 epiphysal cartilages, which grow to such a length before they become 

 ossified, and even afterwards continue to enlarge ; and the latter is pro- 

 bably effected principally in the short bones, which do not contain vessels 

 until just before the commencement of ossification. Notwithstanding 

 this, however, it is not intended to imply, that a cartilage cannot grow, 

 nor become ossified without vessels ; but although the latter condition 

 does in fact obtain in animals, and probably also in man, 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 produc- 

 tions, 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 sur- 

 rounds 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 with effervescence in acids, and differing in size 

 in different bones, from immeasurable minuteness up to 0*001, or even 

 1-002 of a line ; their size, however, does not appear to be regulated 



