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To the typical slime producing species belongs the microbe of the long whey 

 (Lactococens hollandiae},, which particularly before the introduction of pure cultures 

 in the dairy industries, played an important part in the fight against cheese de- 

 fects in North-Holland, and is still here and there practically used to that end. 



Further I have found that the popular food known in Norway as tjaette 

 molken, a sample of which I owe to the kindness of Mr. Pennink of Rotter- 

 dam, consists of milk, in which the long whey microbe, or at least a nearly 

 allied form, secretes acid and slime. 



Other materials in which these and allied microbes occur, were till now 

 unknown, evidently because of the uncertainty about culture conditions and the 

 lack of a good accumulation method. Taking the idea species in the broad 

 sense, I think there is no objection as to bringing the group of forms, found 

 in the manner described below, to the species just mentioned. 



Starting from the following properties, the most characteristic for the mi- 

 crobes of the slimy lactic acid fermentation : 



I st . The optimum temperature for their growth is at 20 or lower, 



2 nd . they can only compete in anaerobic cultures with the other microbes, and 



3 rd . the medium must consist of substances containing peptones as nitrogen 

 and carbonhydrates as carbon source, I succeeded in finding a method giving 

 rise to their accumulation. 



It is true that I only examined a single material in this way, the common 

 baker's yeast, but the investigation of the soil of fermenting or fermented sub- 

 stances, in short of materials of most varying description may be done in a 

 corresponding way. 



The experiment is arranged as follows. 



Into a 30 c.c. closed bottle, filled with maltextract, to which is added l / 8 % 

 of peptone siccum and which contains c. a. 10% extract, a little pressed yeast 

 is introduced, for instance '/* gram. Placed at a temperature of 18 to 20 C. a 

 quiet fermentation sets in, which is allowed to continue 24 to 72 hours, whereby, 

 because of the absence of air the yeast hardly grows, but the various lactic acid 

 ferments reproduce quickly. Other microbes do not develop. Not seldom in this 

 first culture have the contents of the flask already become somewhat slimy. 



Whether this be the case or not, a not too small quantity from it is trans- 

 planted into a bottle quite filled with boiled, air-free milk, for instance 1/2 c.c. 

 into 30 c.c. of milk. At the same low or a somewhat higher temperature only 

 a flora of lactic acid ferments can develop, and if the slime-forming species is 

 present, it is the most vigorous. We then see that after 2 or 3 days the milk 

 become slimy and by inoculation into milk whey, a culture will start which 

 sometimes differs so little from the ordinary long whey, that we may conclude 

 to an identity of species. 



Of course, I cannot foretell that such microbes occur in any yeast sample 

 taken at random, hence I must add that for my experiments I used pressed 

 yeast from the Yeast and Alcohol manufactory at Delft. 



Such a culture in milk differs it is true in some respects from what is 

 obtained by growing long whey from North Holland in milk, as in the former 



