Soemmering has described in a particular work the part that the absorbents perform in the different diseases of the adult and the other ages. This part has appeared to me to be often very difficult to be known, notwithstanding what he has said of it. I refer however to his work on this point.
In old age, nutritive absorption continues very active; for it is that which decomposes the body, which takes from it the substances that nourish it, and which consequently withers and dries the organs.
The external absorptions, on the contrary, are feeble; the skin takes with great difficulty the different contagions, as I shall say in treating of this organ; the mucous surfaces absorb slowly; but little chyle passes into the blood in proportion to what enters it in the adult. The two absorptions, the nutritive and the external, are exactly reversed at the two extreme ages of life; the second is superior to the first in infancy, the first predominates in old age.
As to the internal absorptions, as those of synovia, of the serous surfaces, of the cellular texture, &c. I should think that they predominated in old age, and that to this was to be attributed the numerous serous effusions which happen at that age, and which we observe in dead bodies. We have not however upon this point so good data as upon the other two.
V. Preternatural Absorption.
We can understand two things by this expression; 1st, the absorption of fluids different from those naturally taken by the absorbents, as that of effused blood, &c. I have already spoken of this absorption; 2d, that which takes place in the cysts which are developed contrary to the natural order in the economy. Now this last exhibits a very singular phenomenon, when compared with preternatural exhalation. It, in fact, takes place with difficulty; it is rare that you see the fluids of encysted tumours enter suddenly the circulation by absorption, either in whole or in part, as this very often happens in the serous collections of the peritoneum, which, without being cured, have many alterations of increase and diminution. What physician has not observed that the urine flows more as the abdomen becomes flat, and that it is suppressed when it is filled?
Observe on the contrary, that exhalation is renewed with great facility in encysted tumours; that if we empty them and do not remove their cysts, they are soon reproduced, as I have said. Is it that the absorbents are not developed in proportion to the exhalants in these tumours? I know not; but the fact is not less certain; observation of diseases proves it every day.