220 Theobald Smith 



cloaca: type fully loo per cent, is formed. Again the fraction 

 -^ for B. colt is approximately f while that for B. cloaccz is 



I or \. The reaction of the fluid in cultures of the latter is 

 feebly acid while for the B. coli group it is always strongly 

 acid. Grimberf' in his studies of an anaerobic organism 

 ascribes the greater production of CO^ to a greater formation 

 of alcohol and the more abundant production of H to a greater 

 formation of acid in accordance with the following formulae : 



CeH,A=C.HA+2CO,+4H.-. ^ = 1^ 

 C,H,A=C.H,„0+2C0,+ H,O.-. ^=;^ 



This would agree well with the feebly add reaction of cult- 

 ures of B. cloacce and the strongly acid condition of those of B. 

 coli. 



Another phenomenon constantly observed is the great pre- 

 dominance of H over COj in either type when only a little gas 

 has been formed as in peptone bouillon containing traces of 

 muscle sugar. The same phenomenon is noticeable when the 

 gas at different stages of the process is examined. This may 

 be illustrated by the three following stages in the gas produc- 

 tion by B. cloaca. 



After 22 hours 37.5 per cent, gas has accumulated ; COj, 

 46.6 per cent. ; H,. 53.4 per cent. 



After 22 hoursf 73 per cent, gas has accumulated ; CO.;, 61 

 per cent. ; H, 39 per cent. 



After 96 hours 95 per cent, gas has accumulated ; CO.^, 70 

 per cent. ; H, 30 per cent. 



* We should not ascribe more than a comparative value to this frac- 

 tion for the reason that Co, is much more soluble in water than H. 

 Thus at 20° C. one volume of water takes up 0.9014 volumes of CO, and 

 only .0193 volumes of H. If we bear in mind that at the beginning of 

 fermentation a comparatively large quantity of CO^ may become ab- 

 sorbed in the bouillon the relation of CO^ to H in the fermentation tube 

 will be understood to be entirely different from the ratio obtained by 

 exact analytical methods. 



t A second tube inoculated with the first but having produced gas 

 more promptly. 



