ALCOHOLIC FERMENTS. 203 



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, namely, turbidity 

 and changes in taste and odour ; in this respect they also 

 differ from Hanserfs Mycoderma. Lasche is inclined to 

 assume that the chemical composition of the wort has no 

 influence on the disease caused by Mycoderma, since, in his 

 experiments, the disease was produced in worts of high 

 extract and in worts of low extract, in worts which were rich 

 in sugar and in worts containing little 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 carbonic acid and water, in others into acetic acid ; 

 fatty acids are also said to be formed, and these are oxidised 

 and ethereal salts produced (Schulz). 



Winogradsky found that the Mycoderma occurring on 

 tvine, prepared in pure culture by Hanserts method, changes 

 its form with the composition of the nutritive solution ; he 

 experimented partly with solutions, the mineral constituents 

 of which remained constant whilst the organic substances 

 varied, and partly with solutions in which the reverse was 

 the case. 



Although De Seynes, Reess, Engel, and Cienkowski 

 claimed to have found ascospores in Mycoderma, it has not 

 since been possible to bring about this formation. It would 

 appear from the figures given that the fat globules which 

 occur in many unicellular fungi during the resting stage had 

 been mistaken for spores ; in some cases the mistake appears 

 to have arisen through the presence of an admixture of true 

 Saccharomycetes. The old name Mycoderma is therefore 

 more appropriate to this fungus than the new term 

 Saccharomyces. 



