The pulse was relatively slow in rate as compared with the degree of temperature elevation, running between 90 and 100 beats per minute in the large majority of cases. At the height of the disease it was full and easily compressed. No irregularities were noticed. With recovery it fell promptly to normal. The respiratory rate showed only moderate elevation, being between 20 and 26 in most cases. In a few instances a rate as high as 32 was recorded at time of admission to the hospital, but this promptly fell with rest in bed. A respiratory rate rising above 26 after the third or fourth day of the disease nearly always indicated a beginning pneumonia. With recovery the rate promptly fell to normal. Cyanosis did not occur in the absence of pneumonia. Aside from the manifestations of a profound toxemia, influenza was preeminently characterized by symptoms of respiratory tract infection. The appearance of respiratory symptoms occurred at varying intervals after the onset of the disease, being well developed by the end of twenty-four hours in most cases. A progressive attack upon the mucous membranes of the respiratory tract was universal, beginning with coryza and pharyngitis and progressing to tracheitis or _vice versa_. Further extension of the infection to the bronchi, however, was by no means universal, 49 cases in the group studied recovering without developing evidence of bronchitis. Sore throat was rarely complained of, and laryngitis, possibly due to secondary infection, occurred only once. The progress of the infection was marked subjectively by sensations of irritation, stinging, and a feeling of tightness. A profuse, thin, mucoid exudate appeared; the pharyngeal walls and the soft palate showed a characteristic deep red granular appearance. The onset of tracheitis began with a sense of burning and tightness beneath the sternum accompanied by a harassing cough, at first nonproductive, later with the outpouring of an exudate becoming productive. The sputum varied in character between a scanty, thin, mucoid sputum and a profuse, frankly purulent sputum in cases subsequently developing an extensive bronchitis. Hemorrhage from the mucous membranes was common. Epistaxis occurred in 12 per cent of the cases and was often profuse. The sputum contained fresh blood in varying amounts in 24 per cent of the cases; 51 per cent of the cases developed signs of bronchitis. In 15 of these the bronchitis was mild, probably limited to the larger bronchi, physical examination showing only inconstant sibilant and musical râles. The sputum in these cases was neither profuse nor frankly purulent; 36 cases developed a fairly extensive purulent bronchitis as manifested by more or less diffusely scattered moist râles and by moderately copious mucopurulent or frankly purulent sputum. This bronchitis was not accompanied by an increase in the respiratory rate or by cyanosis unless pneumonia subsequently developed.