CHANGES PRODUCED BY A SAPROPHYTIC ANAEROBE 385 



was opened and the mercury in the gas burette lowered. By 

 this means a sample of gas was drawn in, measured and analysed. 

 Figure 2 shows the details of the connection made at (D) figure 1 . 



The efficiency of our apparatus and pump was judged by the 

 amount of oxygen in the gas obtained for analysis. In a few 

 analyses we obtained a slight reduction in volume after absorbing 

 the gas with alkaline pyrogallate solution. In such a case we 

 calculated the air in the gas by multiplying the amount of de- 

 crease by five and making corrections in the calculation. These 

 amounts were, however, usually nearly within the error in reading 

 our burette. The apparatus used for the analysis of the gas is 

 described by Burrell and Piebert (1913) and is a slight modifica- 

 tion of that described by Haldane. 



Calculations. The following example will show the calcula- 

 tions necessary in this connection. These were used throughout 

 and for that reason the figures for each analysis are not included. 



21.65 cc. of gas taken 



5.63 cc. after CO2 absorptioa 

 16.02 cc. of CO, 



5.63 cc. after Oj absorption 



0.00 cc. of O2 



18.45 cc. of CO2 free air added 

 24.08 cc. total volume 

 16.85 cc. after combustion 



7.23 cc. decrease due to combustion 



7.19 cc. after CO2 absorption 



0.04 cc. of CO2 due to combustion 



4.82 cc. of hydrogen (| of decrease) 

 73.99 per cent CO2 

 22.26 per cent Hj 



3.71 per cent residual gas (by measurement) 



The 0.04 cc. of CO2 due to combustion was disregarded, since this 

 amount is insignificant. 



After the completion of the gas analysis, air was allowed to 

 enter the apparatus through a cotton plug. The bottle was then 

 removed from the incubator and the examination completed. 

 The bottle was opened as carefully as possible and a sample taken 

 for cultural purposes. From this sample stains, shakes and 

 plates were made. The cultures were incubated several days at 



