[ 408 ) 



lil a lliird case in: 



Distilled water 100 



K,HPO, 0.02 



(NHJ.SO, 0.02 



Na., CO., 0.01 



"Mineral solution" 2 dro[)s 

 after cultivatinu' from 5 May to 1 Dec, 155 niui-s. of }»ei'nianganate 

 per litre were fonnd. 

 In a cnltnre in : 



Distilled water 100 



Na.HPO, 0.02 



KOI 0.02 



KNO3 0.02 



"Mineral solntion' 1 drop 

 from 1 June to 1 Dec. we fonnd 165.5 nigrs. of dry haeterial snl)- 

 stance, corresponding witli ca. 83 mgrs. of permanganate j)er litre. 

 As we see, the differences are considerable. 



When a little natrinm acetate was added to the anorganic solution, 

 and when using a pure culture for iiiocidaticui. we could neither 

 state an augmenting nor a diniinishiug of urowlh. 

 Thus we ol)tained in : 



Distilled water 100 



KCl 0.02 



KNO., 0.1 



Xatrinmacetate 0.02 



K.,HPO, 0.02 



"Mineral solution"" 1 drop 

 hy means of weighing, 220 mgrs. of dry bacterial snbstance per litre, 

 corres})onding with 110 mgrs. of permanganate, which figures are 

 not exceedingly high and might likewise have been prodncedi n the 

 same time (4 months) from the air alone, without acetate. 



In all these experiments with distilled water, the free surface of 

 the liquid ^vas also 80 cM', and the air had to pass through a 

 dense cotton ping, Avith which the ERLENMEYER-flasks were closed. 

 Already before ^ve dreAV attention to the importance of the way in 

 which the flasks are closed ; be here still mentioned that we made 

 some special experiments, which proved that a very narrow opening 

 of the flasks, slackens the growth of B. oUgocarhopldlus, so that years 

 may go by before the film has vigorously developed. We could 

 not, however, expected anything else, for the considerable volume of 

 air, required for the growth of the said quantities of bacteria, can 

 oiilv verv slowlv diffuse inward and outward throuo-h the narrow canal. 



