Johann Peter Frank1 in 1794 first gave a definition for diabetes insipidus when he described it as a long-continued abnormally increased secretion of non-saccharine urine which is not caused by a diseased condition of the kidneys. Thomas Willis,2 however, had previously recognized a distinction between a saccharine and a non-saccharine diabetes by discovering the fact that, in certain cases of polyuria, the urine had a sweet taste. The two first cases of diabetes insipidus, reports of which were collected and published in English, were recorded by Dr. Simmons3 two years before Frank's work appeared, and are of such historical importance that it is of interest to quote them in some detail. AN ACCOUNT OF TWO CASES OF POLYDIPSIA, OR EXCESSIVE THIRST "Almost all the modern nosologists have introduced into their systems a disease, to which, on account of the excessive thirst that forms its characteristic