180 COMPARISONS OF RESPIRATORY EXCHANGE. 



mouth- and nose-breathing were not compared. Accordingly, in addi- 

 tion to the series of comparisons made with the tension-equalizer unit 

 on the effect of changing the method of breathing, a second series was 

 made with the spirometer unit. Since this type of apparatus provides 

 for a qualitative and quantitative graphic record of the ventilation, 

 the differences in the character of the respiration can be studied. 



The pneumatic nosepieces were used in all of the experiments but 

 one. The respiration-rate was recorded from the bell of the spirometer 

 and the pulse-rate was, as usual, obtained with the Bowles stethoscope. 

 A record of the muscular activity was secured by means of a pneumo- 

 graph placed about the hips or from the self-recording bed. With the 

 exception of M. J. S., the subjects were all accustomed to the apparatus. 

 The details of the five experiments in the series are here given. 



STATISTICS OF EXPERIMENTS. 



P. F. J., February 14, 1 91 #. Subject had breakfast about 7 h 30 m a. m.; 

 experiment began at 10 h 40 m a. m. Pneumatic nosepieces, 2 periods; mouth- 

 piece, 2 periods; preliminary period, 15 minutes; periods with nosepieces and 

 mouthpiece alternating. Subject stated that he was somewhat sleepy in the 

 second period and that he liked the nosepieces better than the mouthpiece. 

 No observations of the pulse-rate. Average barometric pressure, 769.5 mm. ; 

 average temperature of air in apparatus, 22.1 C. 



P. F. J., July 10, 1912. Pneumatic nosepieces, 3 periods; mouthpiece, 

 3 periods; periods with nosepieces and mouthpiece alternating. Subject 

 uniformly quiet. Pulse-rate uniform except in fifth period, when it was low; 

 respiration was rapid and shallow in this period, but otherwise fairly uniform. 

 Average barometric pressure, 759.4 mm. ; average temperature of air in appa- 

 ratus, 22.5 C. 



J. K. M., July 9, 1912. Pneumatic nosepieces, 3 periods; mouthpiece, 

 3 periods; preliminary period, 57 minutes; periods with nosepieces and 

 mouthpiece alternating. Subj ect preferred nosepieces, as in breathing through 

 mouthpiece his mouth became dry. Pulse-rate uniform in first three periods; 

 in fourth, a tendency to fall; in fifth and sixth, a tendency to rise. Respira- 

 tion-rate fairly uniform in all except the second period for each type of breath- 

 ing, when there was some apncea. Average barometric pressure, 760.8 mm. ; 

 average temperature, 24.2 C. 



T. M. C., July 11, 1912. Pneumatic nosepieces, 3 periods; mouthpiece, 3 

 periods; periods with nosepieces and mouthpiece alternating. Subject quiet 

 throughout experiment; said it seemed easier to breathe with mouthpiece. 

 During periods with mouthpiece he swallowed frequently. Slightly drowsy 

 at the end of third period with nosepieces. Pulse-rate very uniform; respira- 

 tion-rate uniform. Average barometric pressure, 755.7 mm. ; average temper- 

 ature of air in apparatus, 22.3 C. 



M. J. S., July 27, 1912. Mouthpiece, 3 periods; glass nosepieces, 2 periods; 

 periods with mouthpiece and nosepieces alternating. Subject made a few 

 slight movements during the second and third periods with mouthpiece. 

 Pulse- and respiration-rates uniform. Average barometric pressure, 754.9 

 mm. ; average temperature of air in apparatus, 21.1 C. 



