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. 



