250 MICRO-ORGANISMS AND FERMENTATION. 



ditions, 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 peculiarities 

 in its composition, which specially favours the development of 

 Mycoderma. It is to be hoped that further investigations 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. LASCH& 

 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. 

 Mycoderma. LASCHE is inclined to assume that the chemical 

 composition 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. 



It is frequently stated that the chemical activity of certain 

 species of Mycoderma, on the surface of vinous liquids, is a 

 process of oxidation by which alcohol is converted in some 

 cases into carbon dioxide and water, in others into acetic acid ; 

 higher fatty acids are also said to be formed, and these may 

 be converted into ethereal salts (ScHULz). 1 



LAFAR discovered a budding fungus resembling Mycoderma > 

 in the cask-sediment of a lager beer, which produces acetic 

 acid fermentation. The developed film of this species exhibits 

 the typical appearance of the corresponding growth-forms of 

 Mycoderma cerevisice. 



WINOGRADSKY found that the Mycoderma occurring on wine, 

 prepared in pure culture by HANSEN'S method, alters its shape- 



1 Ad. Mayer, Lehrbuch der Gdrungschemie, p. 213, 1879. 



