In reviewing the history of the various diseases, we find that our knowledge concerning them has not always advanced in a steady progressive manner but has been marked by periods of great activity followed by longer or shorter intervals of comparative quiescence.
During the past few years our knowledge concerning the particular disease under consideration, namely, tuberculosis of the kidney, has made most remarkable advancements and the chief factors which have brought this about are two: first, the discovery and perfection of the cystoscope, which lent such an impetus to the study of the diseases of the urinary organs in general; and, second, frequent and early operations on the kidneys, which have enabled us to study the actual pathology of the living. While these factors are undoubtedly the means by which the advancement in our knowledge was attained, the real fundamental feature of the knowledge consisted in the recognition of