Senior Joint Tuberculosis Officer to the Surrey County Council ; Author of " Sanatoria for Consumptives," etc. CLASSIHCATIO~; in pulmonary tuberculosis is needed for administrative or for clinical purposes, from a collective or an individual point of view. The principles which should guid e us in these various cases are the same, but their application is necessarily different. In every case we should have groups of the same nature, so as to be able to. compare similar m~terial under similar

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... itions, and should make our chief grouping from relatively enduring characters and Our subclasses from those which are less permanent; our groups should be capable of accurate definition, mutually exclusive, and cover-~ng the Whole ground i and if our classification concerns the general practitioner in an isolated district as well as the expert with full laboratory facilities, it must depend solely on factors which can be recognized and measured by simple means, not requiring X-ray pictures" complement fixation tests, or post-mortem examinations. For clinical service we need a more complete analysis of cases than for administrative purposes ; but we can only use a few of the chief factors for our classification, leaving the rest for condensed case sum-.maries by which to estimate progress and the effect of remedies. It is the absence of such analysis which destroys the value of published statistics on the results of tuberculin or sanatorium treatment or" of other special remedies, but a classification to include all the necessary factors would be much too complicated for general use. After dividing our cases according to age, sex, and the existence at some time (or otherwise) of tubercle bacilli in the sputum, there are three main data required for a practical classification : (i) The nature and amount of local changes ; (2) the degree of functional disturbance ; (3) the presence or absence of serious complications. Any classification which ignores these three essential factors will not give a true picture of the gravity of the case. The degree of constitutional disturbance is not at ali invariably proportional to the amount of local change, for we may have a very limited lesion with very severe general disturbance, and vice versa ; so that we must subdivide each anatomical group according to the degree of functional change, which (with a ternary cIassification) makes a