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. It will suffice to mention the fact that _diabetes_, though very rare, may yet occur in childhood, and that as a rule it is more dangerous in childhood than in the grown person. Whenever a child loses flesh without obvious cause, suffers much from thirst, and at the same time passes urine in greater abundance than in health, the possibility that it may suffer from diabetes must be borne in mind. Of far greater frequency than any other affection of the kidney is that in which the child passes _gravel_ with the urine, either in the form of a reddish-white sediment, which collects at the bottom of the vessel as the urine cools, or of minute glistening red particles, which resemble grains of cayenne pepper. These deposits, when abundant in the male child, have a tendency to collect in the bladder, and there to form a stone. This painful disease, too, is so much more frequent in childhood than at a later age, that more than a third--indeed, nearly half--of all the operations for stone performed in English hospitals are done on boys under ten years old.