=Diseases of the Kidneys.=--The _kidneys_ perform very important duties in carrying off from the system a large amount of useless material, and thus supplement in many respects the action of the skin, and the purifying influence which is exercised by the air on the blood, as it passes through the lungs.
It is evident, therefore, that their disorder in any way must be a matter of serious moment, though at the same time the knowledge of the skilled doctor is needed to determine the nature and degree of the ailment from which they are suffering, since that requires an examination of the urine, both chemically and by means of the microscope. My remarks on these diseases must consequently be few and fragmentary.
In the grown person, what is known as _Bright's disease_ is of frequent occurrence, assumes different forms, and depends on various causes. In the child it is comparatively rare, and is scarcely ever met with except as a consequence of a chill, or as a result of scarlatina. In these conditions the kidneys become overfilled with blood or congested, and the congestion may pass into inflammation, by which their structure may be irreparably damaged. Dropsy is the great outward sign of the affection--either slight swelling of the face, eyelids, and ankles, or very great swelling of all the limbs, and even the abundant pouring out of fluid into the belly. The degree of dropsy is, however, by no means an absolute measure of the amount of kidney mischief. It therefore behoves every parent to follow out all directions most scrupulously even in cases of very slight dropsy, in order to guard against the risk of permanent injury to the kidneys being left behind; and especially to remember the liability to the occurrence of dropsy and disease of the kidneys after scarlatina. Any check to the action of the skin while it is peeling or desquamating, as it is termed, is especially liable to be followed by these accidents. To avoid all risks as far as possible, I have been accustomed for many years to insist on a child remaining in bed for one-and-twenty days after the first appearance of the rash in even the mildest case of scarlatina, and I am absolutely sure that it is the height of imprudence ever to neglect this precaution.