THE OSSEOUS SYSTEM. 315 



in a certain measure, with a single primordial cell, and represents all the 

 descendants which in course of development have proceeded from it. In 

 the one case, all these newly-formed cells are disposed, one behind the 

 other, in a single or double linear series ; and in this way are produced, 

 by their further increase, the rows of cells above described, whilst in the 

 other they constitute a more globular mass. The primordial cells (first 

 parent-cells) during this procedure, sometimes disappear as distinct or- 

 ganisms, owing to the coalescence or fusion of their walls with the inter- 

 stitial substance, sometimes not ; and the same holds good with those of 

 the subsequent generations. The latter is usually the case in the rounded 

 masses of cells, owing to their smaller size, and around them a contour 

 line may for the most part be recognized, which is nothing more than 

 the distended wall of the first cell ; whilst in the rows of cells, the walls 

 of the original cells are not, usually, so merged in the intercellular sub- 

 stance as to escape recognition. The entire matrix, in which the just- 

 described, enlarged, and actively multiplying cells are enclosed, varies 

 very considerably in thickness in the different cartilages ; scanty around 

 the osseous nuclei in the epipliyses and short bones, it is \ to \ a line 

 thick in the diaphyses. It is universally characterized by its yellowish, 

 transparent color, and its streaky, apparently fibrous fundamental 

 structure, from the other cartilaginous parts, which are, as usual, bluish- 

 white, with a homogeneous or granular interstitial substance. 



The vessels met with in the ossifying cartilages constitute a phenome- 

 non well worth attention ; from the middle of foetal life onwards, they 

 occur in many situations, preceding by a shorter or longer time the 

 appearance of the osseous nuclei, and accompanying their increase. I 

 have observed them in the articular cartilage of the epiphyses of the 

 long bones even in a person 18 years old. They entered the cartilage 

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

 ing a little below its free surface. The cartilage-vessels invariably lie 

 in wide canals (measuring, even in a five months' foetus, 0-02-0-04 of 

 a line), excavated in the cartilage, and bounded by narrow, elongated 

 cartilage-cells, the vascular canals of cartilage, 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), 

 penetrate 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 dilata- 

 tions. These canals are produced by a resolution of the elements of the 

 cartilage, in the same way as the medullary cavities of the bone itself, 

 originally contain a plastic material composed of minute rounded cells 

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

 develop in a short time out of this material, true sanguiferous vessels, 



