The serous membranes are the frequent seat of hemorrhages. The examination of dead bodies incontestably proves it. Nothing is more common than to find in the peritoneum, the pleura, the pericardium, &c. a serum, reddish if a little blood is effused, very red if more, and even pure blood is found under certain circumstances. I have made these observations in two different cases, 1st. After inflammations whether acute or chronic, especially the last. The serous sac then contains a greater or less quantity of blood, sometimes alone, more frequently mixed with serum, and now and then even with whitish and albuminous flakes. The previous inflammation seems to rank these hemorrhages among the active. 2d. Often at the end of organic diseases, in which the exhalations of serum increase almost uniformly in the serous sacs so as to produce dropsies evidently passive, a greater or less quantity of blood is mixed with this serum. What anatomist has not observed these bloody effusions in the pericardium, the pleura, &c.? I have observed that the tunica vaginalis and arachnoides are infinitely less subject to them than other similar sacs; I have never seen them in the last, and twice only in the first. I of course do not speak of the hemorrhages that are the effects of wounds of the head and in which the blood is effused between the two folds of the arachnoides. I have carefully examined the internal surface of the peritoneum, the pleura, and the pericardium, after this kind of hemorrhages, produced either in consequence of the inflammation of the membrane itself, or of an organic disease; their surface has appeared to me to be perfectly sound, so that it is very evident that the exhalants have furnished blood, instead of the serum they threw out there before. I compare a serous surface preternaturally pouring out blood after inflammation, with the active hemorrhages of the mucous surfaces. On the other hand, when the serous exhalants throw out blood at the end of organic diseases of the heart, the womb, the lungs, &c. it is certainly the same phenomenon, as when blood brought by the mucous exhalants, under like circumstances, is thrown off by spitting, vomiting, or stool. Are there cases during life, in which the blood, poured out by exhalation upon the serous surfaces, is afterwards taken up by absorption? I believe that it may happen after inflammation, though we are possessed of no positive facts upon the subject. Cruikshank and Mascagni have seen the blood absorbed by lymphatic vessels, after wounds of the chest; why might not that happen after hemorrhages by exhalation, which takes place after those from rupture?