I shall not go back to the various proofs which establish the cellular structure of the serous system; almost all these proofs are applicable to the synovial system, which appears to be but a net-work of absorbents and exhalants. Hence it is easy to understand what the red and fatty bunches are that are found around the articulations. They perform in regard to this membrane the functions of the abundant cellular texture which envelops the peritoneum, the pleura, &c. &c. It is there that the blood vessels divide ad infinitum before arriving at the membrane where their ramifications, successively decreasing, finally terminate in the exhalants. If a remarkable redness sometimes distinguishes these bunches from the cellular texture, it is because the vessels are more concentrated and nearer together in them. For example, in the articulation of the hip, the synovial membrane of which, almost everywhere adherent, only corresponds in the fissure of the cotyloid cavity with the cellular texture, nature has placed there almost all the arterial ramifications that furnish the synovia; hence the reddish tinge of the cellular bunch that is found there. On the contrary, at the knee where much cellular texture surrounds the whole external face of the synovial sac, the vessels more scattered leave to this texture the same colour as that of the external face of the serous membranes, &c. This redness of some pretended synovial glands, the only character that distinguishes them, is then as it were merely accidental; it no more indicates their glandular nature, than it proves it in the pia-mater, in which it is owing to the same cause. Though the synovial membrane is very analogous to the serous surfaces, it must however exhibit differences of texture, since the fluid it exhales is a little different. In fact, by examining it at the femoro-tibial articulation, where it can be found in considerable pieces, it is seen to be more dense and compact than the serous membranes. Its texture has not the suppleness of theirs; when dried, it is much more brittle; it remains stiff, whilst the serous texture is moved in all directions without the least effort. It resists maceration longer. _Properties._ The properties of texture become evident in articular dropsies, in which the synovial membranes are at first much distended, and in which they contract after the puncture, an operation however that is very rare. Yet it appears that these membranes are only susceptible of a slow and gradual extension. We know that suddenly separated in luxations, their parietes tear instead of stretching; they unite again after the reduction.