AIR AND WATER FOR MICRO-ORGANISMS. 123 



made with the drop-growths on gelatine. The highly interest- 

 ing fact is thus brought out t}iat the bacteria present in the 

 water examined were not able to develop in beer, even when they 

 had been introduced in considerable quantity. With regard to the 

 wort, in view of the above results I am inclined to the opinion 

 that the infection was caused, not through the abundance of 

 the water bacteria, but rather by the presence of certain species 

 which have the special power of attacking wort even when 

 undiluted such species may be termed wort bacteria. 



Based upon these observations, I have elaborated the 

 following method for the analysis of the water of Old 

 Carlsberg : 



One drop (0*04 cc.) of the water was added in the 

 manner described above to each of a series of 1 5 flasks con- 

 taining wort, and to each of a similar series containing beer, 

 also O'25 cc. of the water was added to each of a series of 

 10 flasks of either kind ; these were then shaken and set aside 

 for a fortnight at a temperature of 24-25 C. The beer con- 

 tained in these flasks was low-fermentation lager beer, and the 

 wort (about 14 per cent. Ball.) was that employed for the 

 production of such beer. 



An analysis made in November by means of this method 

 showed that I cc. of the water gave only I 3 growths of 

 bacteria and I 3 of mould i. e. 2 6 in all. No other growths 

 developed, and the beer was not attacked at all. Applying 

 these results to practice, we shall be able to add 2 5 liters of 

 water to a hectoliter of beer without causing any bacterial 

 growth. In December, i cc. of water gave 38 bacteria 

 colonies on a wort-gelatine plate culture, whilst 2*25 cc. of 

 the same water which was distributed between 9 flasks of 

 wort did not give a single growth of bacteria, but gave rise 

 to a growth of mould. The experiment was carried out 

 in the same manner as the previous ones, and, like these, 

 it also showed that the two methods failed to give concordant 

 results. 



