GROUP II. LIQUID ADVENTITIOUS PRODUCTS.
Fluids formed in localities, naturally free from them, are obviously adventitious. Patho logically considered, fluid products are of sig nal importance ; but the consideration of their morbid anatomy will not long detain us.
These fluids accumulate in serous cavities (dropsical); in the cellular tnembrane (cedema or anasarca) ; or in the parenchyma of organs (cedema). They may likewise form in adven titious seats, as in cysts, and in the bullee of erysipelas, nmia and pemphigus, sudamina, &c. When pure, the fluid of dropsy of serous membranes is aqueous, transparent, free from viscidity, and colourless, or faintly yellowish. But it may be thicker, ropy, and of deeper colour,—and is commonly so in ascitic or ovarian fluid, which has been for any length of time accumulating. Especially in cases of this class, organic corpuscles may be found ; other wise the flnid is transparent and amorphous under the microscope. In the fluid of syphi litic rupia we have found well-constituted exudation-cells.
Generally speaking the fluid of dropsy is alkaline,— we have never known it otherwise ; but it certainly is occasionally neutral or even acid. in chemical composition it corresponds very closely with the serum of the blood,— its essential protein-ingredient being albumen in the state of albuminate of soda. As various degrees of inspissation of the fluid occur, the ratio of the solid ingredients to the water varies within rather wide limits. Accidental constituents are biliphwin, urea, and hwmatin. Fat is always present ; and scales of choles tein (visible to the naked eye) are not very unfrequent, especially in dropsy of the tunica vaginalis. Epithelial cells are to be seen in
small quantities (and we have found these calcified) : there is no reason to believe that an excessive quantity of epithelium is necessa rily a part of the disease, though in some cases milkiness or a puriform look may be caused by their extreme abundance. Pus and blood corpuscles may be accidentally present.
The fluid of true dropsy is distinguishable by the deficiency of developmental power : it never forms a blastema for cell-growth ; nei ther is it capable of spontaneous coagulation. But in some rare instances fibrin escapes along with the serum of the blood, —and this in notable quantity, The fluid then becomes coagulable; but it is a mystery why (some times occurring within the body) its coagu lation sometimes does not occur until some hours after its removal from the body. We have seen the contents of the pleura, perfectly fluid when first exposed, become distinctly clotty within an hour mid a half: similar oc currences have been witnessed by others. When coagutation takes place within the body, the coagulum may probably act as a bkisterna. The cause and mechanism of this escape of fibrin from the vessels, and its relationship to inflammation are utterly unknown. In a former place (p. 93) we have spoken of the occasional excretion of fibrin with the urine.