There is after death a great difference between an acute and chronic tumour, between that produced by growth and that by infiltration. In fact, one remains the same, and preserves, until putrefaction, its size, its form, and its density, like all the organs. The other sinks away, as I have remarked, by the loss of the vital forces. This subsidence varies; if the tumour is nothing but the cellular inflation of which I have spoken, and which is so common in external injuries, it entirely disappears; if, besides this inflation, there is an accumulation of blood, as in carbuncle, phlegmon, &c. a portion of the tumour remains, though always much diminished in size. It is generally in this inflation, of the immediate cause of which I am ignorant, that the subsidence especially takes place. Let us pass to a function of the cellular texture not less important, and which is very analogous to this. _Influence of the cellular texture in the formation of cysts._ A cyst is a membrane, in the form of a sac without an opening, which is accidentally developed, and which, containing fluids of a different nature, has been on this account divided into many species. The cysts are formed from the cellular texture; they arise in its cells, grow in the midst of them, and have all its characteristics. To be convinced of the influence of the cellular system in the formation of cysts, it is sufficient to prove that between them and the serous membranes, there is the greatest analogy, and almost identity; for we shall see that these membranes are essentially cellular. The following are some of the analogies of these two kinds of productions, the one of which is natural and the other accidental. 1. Analogy of conformation. The cysts form all kinds of sacs without an opening, containing a fluid that is exhaled from them, having a smooth, polished surface contiguous to this fluid, an uneven, loose one, continuous with the neighbouring cellular texture. 2. Analogy of structure. Always formed of a single layer, like serous membranes, cysts have like them a cellular texture, as is proved by maceration and inflation. Thus they constantly arise in the midst of the cellular organ, usually where it is most abundant. Few blood-vessels enter them; the exhalant system is conspicuous there. 3. Analogy of the vital properties. There is no animal sensibility in them in an ordinary state, but it is very evident in inflammation; organic sensibility is always remarkable in them, and tone, which is characterized by a slow and gradual contraction, in consequence of the artificial or natural evacuation of the contained fluids, &c.; these are the characters of cysts, they are also, as we have seen, those of serous membranes.