70 CAUSES OF HEMORRIAGE,
the effusion. This cause is evidently influential in renal dropsy, in which a constant drain of albuminous serum out of the blood is taking place. It is remarkable that this may have been going on for some, porhaps a considerable time, and yet no dropsy occur, The explanation of this is afforded by the circumstance ascertained by Simon and Christisou, that the decrease of the solid consti- tuents of the serum is not always the leading character in this disease. In three of Simon’s analyses out of four of blood in Bright's disease, the quantity of albumen was decidedly increased —in one instance amounting to 109-4, considerably above the average of health. Cases of dropsy occasionally are met with, in which, as there appears no absolute organic disease, but only an hydramic condition of the blood, one is obliged to conclude that the effusion is dependent on this. Andral mentions that during a famine, where the poorer classes had been obliged to seek a scanty nourishment in roots and herbs growing in the fields, many persons became dropsical. This has not always been observed in famines; but a curious observation of Briicke’s bears upon this point. He confined a frog, having the sciatic nerve of oue leg divided, in a glass vessel for some months. When the frog was insufficiently fed oedema occurred in the leg of which the nerve was divided; abundant animal food removed the edema, which reappeared when the animal was agaiu starved, The occurrence of oedema, in the affected leg only, illustrates the effect of the abolition of neryeus influence in causing local dropsy; the same thing is sometimes, though rarely, observed in infantile paralysis. Dr. Laycock has repeatedly drawn attention to similar facts.
In these instances, it is vory probable that the proportion of albumen in the blood was diminished, as it is clear that the supply of it ordinarily derived from the food was so. When, from cardiac or renal causes, or both combined, together with altered crasis of the blood, the tendency to dropsical effusion is very strong, it is quite remarkable how universal the dropsy becomes, the perito- neu, both pleure, and the pericardium, may be found full of fluid, the arcolar texture everywhere infiltrated, the air-cells of the lungs loaded with frothy serum, the tissue of the brain “‘ wet,” and the subarachnoid fluid considerably increased. In fact, it seems as if tho vessels no longer presonted any containing barrier, but per- mitted the escupe of fluid in every part that it traversed. It is often obseryable in these cases, after death, how the naturally transparent serous membranes have lost this appearance, they look thickened, of a dull whity prey tint, as it were sodden in the fluid. There can be no doubt that this depends on a chronic thickening and increase of their fibrous layer.
Composition of Dropsical Efusions.—This generally approaches more or less closely to that of the serum of the blood. The purer fluids are clear, tolerably limpid, and colourless; often, however, a marked yellow tint is obscrved, which may either arise from dissolved heamatine or from the presence of an increased quantity �
