202 MICRO-ORGANISMS AND FERMENTATION. 



readily thrive in the storage cellar, especially as lager beer 

 forms a much more favourable medium for its growth than 



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wort. This is seen to be the case when traces of a pure film 

 are introduced into lager beer and wort contained in open 

 vessels and left to develop; the culture in the lager beer 

 nearly always remained pure, whilst in the wort various other 

 species made their appearance. 



In Hansels comprehensive series of experiments on 

 Carlsberg beer, it was always found that both lager and export 

 beers were attacked by this fungus ; but there was never the 

 smallest sign that the beer had acquired any disease from this 

 source. The fungus was widely distributed just at those 

 periods when the beer was found to be particularly stable and 

 of good flavour. This has also been confirmed by numerous 

 experiments on lager and export beers conducted by Gronlund 

 and A. Petersen, and those carried out in the laboratory of 

 the author. It is self-evident that we are here only speaking 

 of beer which has been properly treated. In imperfectly 

 closed bottles and casks Mycoderma cerevisice will of course 

 rapidly develop a film, which alone is sufficient to destroy the 

 product. 



Belohoubek was the first who found that under certain 

 conditions Mycoderma can cause considerable injury in the 

 brewery. Subsequently Kukla described a curious cloudiness 

 in lager beer, which had the appearance of a cloud of fine 

 dust in the liquid, and which manifested itself either during 

 storage or after tapping ; he attributes this disease to Myco- 

 derma, and he further assumes that it is the weak wort and 

 also a particular composition which specially favour the 

 development of Mycoderma. It is to be hoped that further 

 investigations will throw more light on this subject. 



Hansen had previously expressed the opinion that the 

 name Mycoderma cerevisice denotes not one, but several 

 different species, and Lasche's experiments have confirmed 

 this. The latter investigator describes four different species 

 which he isolated from cloudy beers. They are distinguished 



