One of these faces adheres to the bone; it unites with it so intimately, that fractures take place any where else rather than here. The means of union are not exactly known; this is certain, that the cartilage is not an elongation, a continuation of the cartilaginous parenchyma of the bone; the fibres of this parenchyma are not continuous with those of the cartilages. If it really was so, by removing from a long bone, fresh and clothed with its cartilage, the phosphate of lime which penetrates it, we should see this continuity, the bone and the cartilage would not differ; now I have constantly observed that in this experiment the action of the acid detaches the cartilage from the bone, either in fragments or as a whole. We see the cartilaginous fibres of the bone deprived of its saline base, terminating evidently on the convex surface which the cartilage embraces; no solution of continuity has taken place. In general, the appearance of the cartilaginous parenchyma, separate from its calcareous portion, is wholly different from that of a true cartilage., I presume that this difference is owing to the quantity of gelatine, which is greater in the second than in the first. The action of the acids, especially the nitric, is the best means of separating a cartilage from its osseous head; maceration does not produce this phenomenon under a great length of time; in ebullition, as the gelatine melts, it is less apparent. The surface of the cartilage opposite to the bone, is intimately united to the synovial membrane of the articulation. It borrows from it the polish which it has; for wherever these substances do not correspond to this membrane, they lose this character, as we see in the larynx, in the cartilages of the ribs, &c. Here the means of adhesion is an extremely compact cellular texture, which neither maceration nor dissection can remove in layers. As the synovial membrane is wholly formed from this texture, it appears that upon the cartilage it is only an elongation of that which, after having contributed to the structure of this organ, is condensed upon its surface and organized as a membrane. The circumference of the cartilages of which we are treating, terminates insensibly upon the osseous surface; it ceases at the place, where the synovial membrane quits the bone to be reflected.