( 407 ) 



If the tap- \v;itei- was replaced by distilled water, tlie production 

 of dry organic substance Avas commonly smaller, which cannot, how- 

 ever, result from the nutrition by substances in the tap-water, oxidisal)lo 

 by kaliumpermanganate, for the 14 mgrs. of permanganate, which 

 our ta})- water consumed per litre, we found quantitatively back, at 

 the end of the cullivation period, in the clear li((uid beneath the 

 pellicle of B. o/ü/0('ar/)Oj)hi/iis, \vhich licpiid can easily be sucked olF 

 with a pipette, without any considerable bacterial contamination. 

 Moreover the experiments with distilled water have likewise exhibited 

 great divergency in production, and though tlie cause has not been 

 established with perfect certainty, we still thiidv if j)robable, that 

 these differences result from the greater or smaller density of the 

 cotton plugs, b}' which the speed of air entrance is greatly influenced. 

 We base this supposition on results obtained with flasks, only 

 differing in the width of the mouths, and to which we shall i-efer 

 later. It is furthermore certain that we have not to do here with 

 the infection of other l)acteria, or with monads, for the pure cultures 

 displayed as considerable div^ergency as the crude ones. Neither caji 

 the chief cause be attributed to a change in percentage of the air 

 in gaseous carbon compounds, the differences being observed simul- 

 taneously in cultures placed side by side in the same locality. 



But we now give some further numbers. In an experiment with : 



Distilled water 100 

 K, HPO, 0.02 



KNO, 0.1 



KCl 0.01 



"Mineral solution" 1 drop 



sterilised and inoculated with a pure culture of B. oUgocarhophilus, 

 were found, after 37 days' cultivation (2 Jan.^ — 19 Febr.) at 23° C, 

 66.6 mgrs. of permanganate, corresponding with circa 133 mgrs. of 

 dry bacterial substance per litre. 

 In another experiment with : 



Distilled water 100 



Na., HPO, 0.02 



KNO, 0.01 



"Mineral solution" 1 drop 



likewise sterilised and after a culture of 40 days, at 23° C. the per- 

 manganate number amounted to 60 mgs., corresponding with 120 

 mgrs. of dry l)acterial matter per litre. 



