It is probable that no system of nomenclature yet devised is capable of meeting all requirements, because of constant additions to knowledge and corresponding variations in classification. This difficulty is especially manifest in medicine, where names are chosen sometimes from fancied resemblances, or from the prominence of certain svmptoms or certain lesions, or on the basis of current and varying clinical or pathologic conceptions; or, worst of all, in intended honor of the discoverer or exploiter. With the progress of knowledge and with more extended observation, however, it not rarely happens that symptoms or lesions considered so distinctive as to be incorporated into the name given a disease, are found to be not invariably present, but are at times so ill developed as to be inconspicuous. Thus, we have learned from experience that typhoid fever may be unattended with typhoid symptoms, or elevation of temperature, or intestinal lesions; exophthalmic goiter,