166 COMPARISONS OF RESPIRATORY EXCHANGE. 



tired in last period. Pressure in bag at end of experiment about 4 mm. of 

 water. Pulse-rate comparatively regular. Respiration for the most part 

 uniform, except in last period, when subject occasionally took a deep breath. 

 Average barometric pressure and temperature of air in apparatus were: 

 Spirometer unit, 754.3 mm. and 20.4° C, respectively; Douglas apparatus, 

 754.8 mm. and 20.9° C, respectively. 



M. J. S., July 25, 1912. — Douglas apparatus, 3 periods; spirometer unit, 

 3 periods; apparatus alternated. Subject lying on couch. With Douglas 

 method, Tissot valves, glass nosepieces, and large bag; with spirometer unit, 

 pneumatic nosepieces which were tested with soapsuds for leaks. Subject 

 preferred Douglas method, as less resistance to breathing. Both pulse-rate 

 and respiration-rate comparatively uniform. Average barometric pressure 

 and temperature of air in apparatus were: Spirometer unit, 751.1 mm. and 

 20.5° C; Douglas method, 751.3 mm. and 21.6° C, respectively. 



M. J. S., July 26, 1912. — Douglas apparatus, 3 periods; spirometer unit, 

 3 periods; apparatus alternated. Subject lying on couch; mouthpiece with 

 both apparatus; rubber-flap valves and large bag used with Douglas apparatus; 

 Douglas bag supported vertically. Subject said he found it more difficult 

 to inhale with rubber-flap valves than with the Tissot valves and preferred the 

 spirometer unit in this experiment. Pressure in bag at end of experiment 

 about 5 mm. of water. Pulse-rate uniform throughout experiment. Respi- 

 ration comparatively uniform, except in last period, when there was considerable 

 irregularity in last half. Average barometric pressure and average tempera- 

 ture were: Spirometer unit, 751.0 mm. and 19.8° C, respectively; Douglas 

 apparatus, 751.0 mm. and 19.0° C, respectively. 



J. B. T., November 15, 1912. — Spirometer unit, 3 periods; Douglas apparatus 

 3 periods; apparatus alternated. Subject sitting in reclining chair; pneumatic 

 nosepieces, with surgeon's plaster over lips and soapsuds around nosepieces 

 with both apparatus; mica-flap valves and large bag with Douglas apparatus. 

 Subject found no difference in breathing with either of the apparatus. 

 Pulse-rate during experiment comparatively uniform. Normal respiration- 

 rate, 18 per minute; respiration during experiment very uniform in character. 

 Average barometric pressure and temperature of air in apparatus were: 

 Spirometer unit, 756.4 mm. and 20.4° C., respectively; Douglas apparatus, 



756.2 mm. and 19.4° C, respectively. 



T. M. C, November 16, 1912. — Spirometer unit, 3 periods; Douglas appa- 

 ratus, 3 periods; apparatus alternated. Subject sitting in reclining chair; 

 mouthpiece used with both apparatus ; mica-flap valves and large bag with 

 Douglas apparatus. Subject stated he found it a little more difficult to 

 breathe into Douglas bag. Pulse-rate uniform. Average respiration-rate 

 before experiment 14 per minute ; respiration during experiment very uniform. 

 Average barometric pressure and temperature of air in apparatus were: 

 Spirometer unit, 764.3 mm. and 18.5° C, respectively; Douglas apparatus 



764.3 mm. and 18.0° C, respectively. 



DISCUSSION OF RESULTS. 



The results of the several comparisons with the Douglas method and 

 the spirometer unit are given in table 25, together with averages for 

 each experiment and a general average for each apparatus for the whole 

 series of comparisons. The general averages for the respiratory ex- 

 change with the Douglas apparatus are lower than those with the spi- 

 rometer unit, being 178 c.c. for the carbon dioxide eliminated, 224 c.c. 



