temperature and acceleration of pulse, with a contraction of the upper and anterior part of the chest, while none of these changes result from bronchitis alone, there should be no difficulty in keeping the line of diagnosis clear between these two diseases. And yet there is probably no more frequent or important error committed in diagnosis than that of mistaking the early stage of pulmonary phthisis for bronchitis. This may arise in part from the fact that bronchitis often supervenes and continues coincidently with phthisis. But the practitioner should remember that whenever there is increased vocal fremitus and diminished resonance in any given case there is some altered condition of the lung-structure, and consequently some form of disease besides bronchitis, however plain the ordinary symptoms of the latter may be at the same time. From pulmonary emphysema, chronic bronchitis is distinguished chiefly by the abnormally-increased resonance on percussion in the former, especially over the upper and anterior parts of the chest, and the peculiar depression of the spaces above the clavicles and between the ribs at the beginning of the inspiratory act, and their return to over-fulness near its close; while none of these changes accompany any grade of simple bronchial inflammation. PROGNOSIS.--In the ordinary form of acute and chronic bronchitis there is very little tendency to terminate fatally except when it attacks infants or persons infirm from age. And even when it occurs at these extremes of life the fatal terminations are usually caused by the supervention of lobular pneumonia as a complication, and not from the bronchial inflammation alone. Severe cases of capillary bronchitis are more dangerous, and in young children and aged or debilitated persons often prove fatal before the end of the first week of their progress by the direct obstruction to the entrance of air into the air-cells of the lungs. The pseudo-membranous or plastic bronchitis is still more dangerous. It has been estimated that one out of every five dies. But the statistics concerning the number and character of cases are not sufficient to furnish a reliable deduction of the ratio of mortality. The duration of acute attacks of bronchitis of all varieties from which recovery takes place is from one to three weeks. Uncomplicated cases of chronic bronchitis seldom prove fatal, neither is there any self-limit to their duration. Many cases undergo marked improvement during the warm {178} months of summer, but suffer a renewal of all the more severe symptoms on the return of the cold and wet weather of autumn. In other cases the symptoms continue nearly the same through all the seasons of the year and until an advanced period of life.