MYCODERMA. 409 



develop a film, which is sufficient, unaided, to destroy the 

 product. 



Belohoubek was the first to observe that, under certain 

 conditions, Mycoderma may cause considerable injury in the 

 brewery. Subsequently, Kukla described a curious cloudiness 

 in lager beer, having the appearance of a cloud of fine dust in 

 the liquid, which manifested itself either during storage or 

 after tapping ; he attributes this disease to Mycoderma, and 

 further assumes that it is weak wort, having certain peculi- 

 arities in its composition, which specially favours the develop- 

 ment of Mycoderma. It is to be hoped that further investiga- 

 tions will throw more light on this subject. 



Hansen expressed the opinion that the name Mycoderma 

 cerevisice denotes not one, but several different species, and 

 Lasche's experiments subsequently confirmed this. The latter 

 investigator describes four different species which he isolated 

 from cloudy beers. They are distinguished from the species 

 described by Hansen by the fact that they produce alcohol in 

 beer- wort ; one yields 0-26 per cent, by volume, two yield 

 0-79 per cent., and the fourth produces 2-51 per cent. Lasche 

 concludes from his experiments that these four species cause 

 diseases in beer, both turbidity and changes in taste and 

 odour ; in this respect they also differ from Hansen's Myco- 

 derma. Lasche is inclined to assume that the chemical com- 

 position of the wort has no influence on the disease caused 

 by Mycoderma, for, in his experiments, the disease was pro- 

 duced in worts of high extract and worts of low extract, in 

 worts rich in sugar and worts poor in sugar. 



Winogradsky found that the Mycoderma occurring in wine, 

 prepared in pure culture by Hansen's method, alters its shape 

 with the composition of the nutritive solution ; he experi- 

 mented both with solutions, the mineral constituents of which 

 remained constant while the organic substances varied, and 

 also with solutions in which the reverse was the case. 



Many experimenters have subjected Mycoderma to close 

 investigation during the last few years, and especially Henne- 

 berg, Heinze, Meissner, Seifert, and Will. Meissner's researches 

 are particularly comprehensive, both morphologically and 

 physiologically, and they concern twenty- three different species 



