l8o OSSEOUS SYSTEM. [sect. 94. 



thin and translucent layer, whose elements, although, morpho- 

 logically, not true lacunae, and also not ossified, are, nevertheless, 

 much more nearly related to lacuna? than to cartilage- cells. Ac- 

 cording to Bruch, the covering at the sternal end of the clavicle is 

 also fibrous. The part of the articular cartilage next to the bone 

 presents an osseous layer, possessing, as Sharpey pointed out, the 

 structure of cartilage but with the matrix calcified, and thus 

 exhibiting, when decalcified, a different texture from that of the 

 ordinary bone beneath (see also Tomes and Be Morgan). The 

 cartilaginous borders of the articular cavities principally con- 

 sist of connective tissue, but invariably contain a few cartilage-cells. 

 Articular cartilages, except during the period of development, 

 as will be hereafter explained, contain no vessels or nerves. 



In the foetus, about the middle of embryonic life, the vessels of the 

 synovial membrane are said by Toynbee (Phil Transact., 1841) 

 to pass much further upon the articular cartilages; of which, 

 however, in the humerus of five to six months' foetuses, and also in 

 new-born infants, I could not convince myself. In pathological 

 conditions, endogenous cell-formations occur in remarkable per- 

 fection, and more especially in the velvety condition of articular 

 cartilages, in which the mother-cells, frequently of very consider- 

 able size, with one or two generations of cells, and also containing 

 fat, lie tolerably free in a fibrous matrix, and can be readily 

 isolated. In adults, the articular cartilages are destitute of vessels, 

 although the vessels of the synovial membrane, at their borders, 

 often extend for some distance over them. That which Liston 

 (Medico-Chir. Trans., vol. v., 2nd series. Lond. 1840, p. 93) describes 

 as pathologically-developed cartilage-vessels, which pass from the 

 bone in parallel lines into the cartilage, and then, after forming 

 loops near the surface, return, are doubtless only the normal 

 vessels of the cartilage, which are still well marked in individuals 

 sixteen years old (see infra). Accordingly, we cannot admit the 

 occurrence of inflammation of the cartilages in the adult; but 

 they, no doubt, become altered in morbid conditions of the ad- 

 joining bone, or inflammations of the synovial membrane; they 

 may split up into fibres, and this with increase of thickness, for 

 Cruveilhier [Biet. cle Med. et de Chir. Prat., iii. 514) saw the 

 fibres six lines in length, which far exceeds the normal thickness 

 of articular cartilages. They wear down readily, and, at last, 

 entirely disappear (in suppurations of the bones or joints), so that 

 the bones become denuded ; they may also suffer partial loss of 



