"Now from these, and similar examples, which have fallen under my observations, I think it may be assumed, that ascites, when proceeding from some visceral disease, (and the principle applies to hydropic effusions from the pressure of disease in other cavities,) does so by the gradual extension of the chronic inflammation of the internal cellular or serous tissues of the diseased organ, to its outer external coverings; and that, commencing here as from a point, the serous or hydropic inflammation is progressively propagated through the whole of the serous membrane of the cavity. By the disease within the cellular tissue of the diseased viscous increasing, a corresponding increase, in these cases, will ensue of the disease on the surface of the membrane investing it; until at length a susceptibility to take on a higher action is induced, which only requires any slight occasional cause to establish. Under this condition of an increased excitement in the peritoneal or other serous membrane, coagulable lymph is discharged into its cellular tissue, and a thickening of it takes place; until at length the operation of paracentesis, which in the early stage of the disease was attended with only inconsiderable inconvenience, becomes an adequate cause of a still higher inflammation, which terminates perhaps in suppuration; and, in the post mortem examination the serous fluid is found so mixed with coagulable lymph, and purulent matter, as to give a whey or milk-like appearance to the mass. The quantity of serous fluid, in these cases, is generally small, when compared with what was accumulated in the intervals of former tappings; for the vascular excitement which occasions the discharge of coagulable lymph, is destructive of that which pours out the serous fluid."
Dr. A. remarks, that, besides the particular facts deduced from observations on dropsy as a local disease, and which prove its relation to diseases of local excitement, there is a further support to be given to these views by various proofs that are afforded from observations upon the urine, of serous inflammation producing local dropsy, being frequently connected with one of a general kind. "So that the inflammatory state of the system becomes sometimes a cause of the effusion into a cavity, and at other times an effect of this state." After giving full credit to Drs. Wells and Blackall for their researches into the state of the urine in dropsy, our author remarks, that there are certain conclusions deducible, which appear not to have been contemplated by those gentlemen, but which are strictly accordant with the pathological views he has endeavoured to establish in the present work.
"According to these facts, it appears, that when the disease of dropsy is under a sub-acute form, and of the anasarcous kind, it is usually idiopathic, and, often originating from cold; and in this state, as well as in the symptomatic form, though in a less degree, the urine is found to contain a portion of serum. It is nearly peculiar to this disease, and denotes, according to the quantity of it contained in the urine, the amount of that excitement in the cellular tissue, and of the general vascular system, which may be termed serous inflammation: for it is met with most considerably in those forms of the disease, in which these particular states of the body are most apparent."
Serum is therefore found in greater abundance, when anasarca precedes the local dropsy, which, in Dr. A.'s opinion, denotes the operation of a general cause. This is found to be the case especially in anasarca after scarlet fever. In cases of anasarca, the skin, kidneys, and bowels are very defective in their operation. Serum is also found, though in a smaller quantity, in those cases in which the anasarca has followed the local dropsy; for the disease of the viscus, which is the cause of the inflammation in the serous membrane of the cavity, may produce an adequate degree of the vascular excitement which gives rise to a discharge in the cellular tissue. Our author sums up his observations on this subject, by remarking, that there appear to be four distinct conditions of the system by which the occurrence of serum in the urine is regulated.
"1. It is in the greatest quantity, where along with a copious and continued effusion, there is a nearly corresponding quickness in the absorption of the serous fluid, and which will occur most commonly when the general excitement precedes, and is cause of the local one.
"2. It is consequently, cæteris paribus, in a less quantity where the general hydropic excitement of the system succeeds, and is dependent on the local one.
"3. It is absent, or found only in a minute proportion, in all those cases where the local increased excitement in the serous membrane is only partially extended to the rest of the system, and where the absorption from the part is inconsiderable; as particularly happens in the encysted kinds, or,
"4. Where the effusion of the serous fluid has proved remedial of the inflammation producing it; in which case the disease, as it respects the presence of water in a part, may visibly resemble another example, and yet be essentially different from it, by the serous inflammation, which produced it in both, having ceased, on its occurrence, in one of them."
Dr. A. discovers a further evidence of the relation which dropsy bears to diseases of local excitement, in the effects it produces on the general system. Thus, during the continued effusion of serum in anasarca, there is sometimes a large quantity absorbed and carried out of the body; by which a regular draught is made upon the nutrient principles of the blood, which must naturally create effects like those arising from the continued discharge of pus from a suppurating surface. In both cases the local disease, when extensive and of long duration, will necessarily occasion an exhaustion of the vital powers, by which that condition of the system termed cachexy will be induced.
"The exhausted or cachectical state, therefore, of the system, which has been so variously accounted for, and so frequently assigned as a principal cause of both local and general dropsy, is a direct consequence of the agency of some power diminishing the vital strength at its source; and in the case of a chronic and long continued serous inflammation, it will proceed from the daily abduction from the circulation of a portion of its vital fluid: and whether it be pus or serum that is drawn from the body; or whether it be from any permanent failure in the supplies of nutriment to it, the effect will be the same, as if a certain quantity of blood was daily abstracted from the system."