PRODUCED BY ALCOHOLIC FERMENTS. 215 



also of the insufficiency and uncertainty of the characters from 

 wJiich brewers judged -formerly exclusively \ and unfortunately 

 still to too great an extent the progress and condition of the 

 fermentation. 



Lasche has also observed some new disease yeasts, a 

 description of which may be expected in the journal of the 

 Chicago Station. 



The above investigations relate exclusively to low-fermen- 

 tation beer. On reading the English brewing literature of 

 recent years, it is seen, from a number of observations, that 

 the wild yeasts can give rise to irregularities to an equally great 

 extent in high-fermentation as in low-fermentation breweries. 

 The experimental investigation of De Bevay, of Melbourne, 

 shows that the beer-disease known in Australia as " summer- 

 cloud " is caused by a Saccharomyces (' The Brewers' Journal/ 

 London, 1889, p. 490). High-fermentation beer which has 

 been attacked by this species of wild yeast becomes cloudy, 

 and acquires a sour bitter taste. This malady is mentioned 

 as one of the most serious occurring in Australian breweries. 



Whence come the Disease Yeasts ? 



In investigations such as those under discussion, the 

 problem is not merely to ascertain the causes of the diseases, 

 but there at once present themselves the new questions : 

 How can we recognise the disease germs ? Where is their 

 habitat ? How do they gain admission into the brewery ? 



As to the characters by means of which the disease yeasts 

 can be distinguished from the good brewery yeasts, these 

 have been described in the above account of my theoretical 

 investigations. The important question of habitat cannot 

 unfortunately be completely answered, and I will here briefly 

 state all that we now know. 



In 1 88 1, I published in the journal of the Carlsberg labora- 

 tory a treatise on Saccharomyces apiculatus and its circulation 



