CLEANLINESS IN BUTTER AND CHEESE FACTORIES. 135 



My investigations concerning the bacteria of ice have 

 also proved another fact, which still more confirms my 

 opinion that recently melted ice-water is to be preferred 

 even to very pure well-water in the dairy work. The in- 

 vestigations showed that in case of bacteria remaining in 

 the ice for a long time their virulence, i.e., their power to 

 develop their specific qualities, was greatly diminished. 

 Their multiplication took place very slowly, and where the 

 bacteria were made up of fermentation-starters, the fer- 

 mentation developed considerably more slowly and less 

 intensely than was usually the case. I also observed 

 that some of the ice-water bacteria which did not show 

 any fermentative power on the first inoculation cultures, 

 after having later reached their normal conditions again 

 possessed this power. The investigations were made both 

 with lactic-acid bacteria and putrefactive bacteria. The 

 former, which caused a complete fermentation in milk 

 before the freezing by being kept for twenty-four hours in 

 an incubator at 86 F. (30 C.), were unable to produce 

 even something like a similar characteristic fermentation 

 in several days after having been inclosed in ice for two 

 weeks. The phenomenon is analogous to that which 

 Eeimers (see p. 130) observed concerning the bacteria from 

 the deep layers of the earth, and also to that shown by me 



shown that " while in some cases the loss may reach as high as 90 

 per cent, it is ordinarily much less." 



Comparative analyses of white and of transparent ice, made by 

 Russell (loc. cit.), show, as the average of 153 determinations, that 

 the latter kind contained a smaller number of bacteria than the 

 former ("snow-ice") ; but in several cases a larger number of bac- 

 teria per cc. was found in clear transparent ice than was found in 

 any sample of snow-ice. W. 



