SECT. 102.] OSSEOUS SYSTEM. I9I 



person sixteen years old. These vessels invariably lie in wide 

 canals, excavated in the cartilage and bounded by elongated 

 narrow cartilage-cells. These vascular canals of the cartilage, or 

 cartilage-canals, pass into the cartilage from the perichondrium, 

 and when a vascular point of ossification is present (diaphysis) 

 also, from the border of ossification ; but there in smaller number, 

 at least in early stages. They ramify in the cartilage in various 

 directions, and without appearing to form anastomoses or other con- 

 nections, apparently end in blind and mostly club-shaped extremities. 

 These canals originate by a transformation of the elements of the 

 cartilage, like the medullary spaces of the bones themselves ; they 

 at first contain a formative substance (cartilage-medulla), composed 

 of small round cells, corresponding to the foetal bone-marrow, 

 out of which, in a short time, are developed true sanguiferous 

 vessels and a limiting wall, consisting of more or less developed 

 connective tissue, and, subsequently, also of elastic fibres. I 

 have found sometimes only one larger vessel (often very distinctly 

 arterial in character, with muscular walls), sometimes two, some- 

 times capillaries in variable number, in one canal; but I am 

 unable to say how the circulation is performed in these vessels. 

 Either anastomoses must take place between the vessels of different 

 canals ; or when the latter are in reality shut, there must be arteries 

 and veins in one and the same canal. The purpose of these car- 

 tilage-vessels appears to be two-fold : first, and more especially, to 

 supply the cartilage with materials necessary for its growth and 

 further development; secondly, to promote the process of ossifi- 

 cation. The former is very obvious in the thick cartilages of 

 epiphyses, which continue growing for a long period before they 

 ossifv, and even after this do not cease enlarging; the latter is, 

 perhaps, best exemplified in the short bones, which do not receive 

 vessels until immediately before their ossification commences. 



The more intimate changes occurring in the formation of the cartilage- 

 canals and cartilage-marrow have hitherto been but little investigated. 

 Virchotv (Arch. v. p. 428) believes he has seen in bones affected with rickets 

 the cartilage-matrix and the capsules becoming streaked and opaque, whilst 

 the cartilage-cells, or primordial utricles, became larger and more granular, 

 and exhibited a multiplication of their nuclei. The matrix, so altered, then 

 passed gradually into undoubted medullary substance, which here and there 

 still enclosed distinct remnants of cartilage, and was composed, for the most 

 part, of larger and smaller granular cells with one or several nuclei, and of 

 the above-mentioned matrix. I agree in all points with the opinion of this 

 author, and have followed the origin of the small cells of the marrow from 

 the cartilage-cells and their metamorphoses into the subsequent contents of 

 the cartilage-canals. 



