In almost all the studies of renal function in nephritis patients have been utilized in whom the nephritis was an established condition. A few experimental studies have attempted to correlate functional changes with the type of lesion produced by the injection into lower animals of nephrotoxic substances such as uranium or bacillary toxins, and to study in a comparative way the value of various functional tests. While making some functional tests in nephritis in the spring of 1915, it occurred to us that scarlet fever was a condition which offered an exceptional opportunity to study the functional renal changes in nephritis in the human being, from before the onset throughout the various clinical phases of the condition, with particular attention to the time relationship. There is no other disease in which nephritis is such a consistent and looked for complication.
Two types of nephritis must be distinguished in scarlet fever.