THE OSSEOUS SYSTEM. 351 



in great number, perpendicularly from the bone, ramifying, and 

 terminating a little below its free surface. The cartilage-vessels 

 invariably lie in wide cauals (measuring, even in a five-months' 

 foetus, 002 — 001'") excavated in the cartilage, and bounded by 

 narrow, elongated cartilage- cells, — the vascular canals of car- 

 tilage, or cartilage canals, — which enter the cartilage from 

 the perichondrium, and, when a vascular ossific nucleus exists 

 (diaphysis), also from the border of the ossifying portion itself 

 (though in less number, at all events at an earlier period), pene- 

 trate it in straight lines, in various directions, giving off a few 

 branches, and, to all appearance without any anastomoses, or 

 other kind of interconnection, end, for the most part, in blind, 

 club-shaped dilatations. These canals are produced by a 

 resolution of the elements of the cartilage, in the same \va\ 

 as the medullarv cavities of the bone itself, originally contain a 

 plastic material composed of minute rounded cells (cartilage- 

 marrow), corresponding to the foetal cartilage-marrow, and 

 develope in a short time out of this material, true sanguiferous 

 vessels, and a wall composed of more or less developed con- 

 nective 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, sometimes capillaries 

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

 circulation is carried on in these vessels. There must either 

 be anastomoses 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 of a double character; 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 probably 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 con- 

 dition does in fact obtain in animals, and probably also in man, 



