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?
The cellular exhalants frequently pour out blood in the cells. 1st. This phenomenon is often very evident in phlegmon or in other similar tumours. By cutting into them, in the dead body, we find blood extravasated in the cells; this is so true, that some authors have made the nature of inflammation consist in this extravasation. But in slight phlegmonous inflammation, the blood undoubtedly remains in the cellular capillary system; it is only in those cases where the inflammation is very great, that this passage takes place. 2d. As to the passive hemorrhages of the cellular texture, who does not know that oftentimes the water in dropsies is reddish? who does not know, that in scurvy, considerable portions of the cellular texture are infiltrated with blood, which has certainly not been poured out by erosion? I injected not long since two subjects, with very evident scorbutic spots on the legs, and there was no kind of extravasation in them; there would have been if the rupture of the vessels produced these spots. As these things did not arrest my attention particularly in former years, I did not pay much attention to many subjects that I have injected with these scorbutic spots. I do not think that they would ever have presented cellular effusions, which would undoubtedly have struck me if they were there, when I dissected bodies for the students.
As to the hemorrhages of the medullary exhalants, we are ignorant of them. I have never seen in examinations of dead bodies, blood effused in the articulations, except from wounds, &c.
As to the nutritive exhalants, it is evident that every sanguineous exhalation is foreign to them.
Preternatural Exhalations, not Sanguineous.
The blood is not the only fluid that sometimes passes by the exhalants instead of the fluids that these small vessels naturally pour out. Who does not know how much the sweat differs? Sometimes water is almost alone transmitted by the skin; at other times the sweat is filled with many substances more or less heterogeneous; it is more or less salt; we know how very different at times is the odour of it. Observe the many substances that are thrown out upon the external surface by the exhalants, in the small pox, measles, scarlatina, &c. in herpetic affections, in different eruptions; compare the critical sweats with those that are natural, and you will see that the exhalants are, if I may so express myself, a common passage, which all the substances contained in the body can pass through, and which in fact they do pass through in certain cases, when, among the numerous modifications of which the cutaneous organic sensibility is susceptible, they find those that are in relation with them. Shall I speak of the serous exhalants? observe that the surfaces of the same name, according as they are affected, pour out many different fluids, a milky serum, and a thick substance that attaches itself to their surface in the form of a compact membrane, &c. If you have opened but little the bodies of those who have died of chronic peritonitis, you must have been astonished at the diversity of fluids then contained in the peritoneum. Grey, yellowish, fetid, without odour, thick, viscid, thin, &c. &c. these fluids are hardly twice the same. The serum appears to be always the general vehicle; but the substances that it contains, by the effect of the change that disease has produced in the vital forces of the membrane, are infinitely variable.
Thus we shall see that the glands are a common way, through which pass, according to the manner in which they are affected, many substances which differ essentially from those that compose the secreted fluids in the natural state.
IV. Of the Preternatural Development of the Exhalants.
The exhalants are developed preternaturally in many parts; it is especially in the cysts that this development is best seen. Their internal surface, ordinarily smooth, pours out very different fluids, according to the particular sensibility they possess. When we open these cysts, the exhalants furnish new fluids, and it is often necessary to remove them to prevent exhalation. Sometimes instead of the fluid that is ordinarily exhaled there, the blood is thrown out, as happens on the serous surfaces; for example, I have found very bloody serum in the encysted dropsies of the ovarium; latterly I have seen in them coagulated blood. I would observe that this is an essential difference to be added to those mentioned above, between the fluids that are exhaled and those that are secreted. These last are never preternaturally poured out in a cyst. We never find preternaturally a quantity of bile, of urine, saliva, serum, &c. whilst we often find serum, as in encysted dropsies, fat as in steatoma and other tumours which have a fatty liquid analogous to this fluid, synovia, as in the tumours called ganglions, when they are not dilatations of the synovial glands, which have cysts preternaturally produced, &c. Whence arises this difference? it would be necessary that the glands should be preternaturally developed in our parts, in order that the secreted fluids might be preternaturally separated from the blood, now the structure of these organs is too complicated, their organization supposes too many conditions, to admit of their preternatural development. On the contrary, the simple organization of the exhalant surfaces, which have only vessels continuous with the arteries, and without an intermediate organ, requires much less for them to grow preternaturally in parts, in which they were before unknown.
Sometimes the fluids exhaled preternaturally do not collect in a cyst; they continually flow out; this is what takes place in fistulas, and other preternatural or artificial drains that are made in our organs. Then the cellular texture, constantly preserving the preternatural modification of sensibility that it has taken locally from a deposit, or any other circumstance, constantly continues to pour out a fluid different from the serum that is exhaled in a natural state.