MICROBIOLOGY OF ALCOHOL AND ALCOHOLIC PRODUCTS. 443 



cerned, but it includes alcohol-forming organisms which produce about 

 6 per cent of alcohol, and bacteria which cause rapid deterioration and 

 spoiling of the fermented product. The pulque is ready for consumption 

 twenty-four hours after the commencement of fermentation and cannot 

 be kept more than a day or two. 



Of the beverages produced from starchy materials the Japanese SAKE, 

 RICE BEER, has been most studied. It is made from rice by the diastatic 

 action of Aspergillus oryzce and yeast fermentation. The process includes 

 three stages. First the preparation of koji which consists of steamed 

 rice on which the spores of the fungus are sown and allowed to grow 

 at 20 until the whole mass is penetrated with mycelium. The next 

 stage is the preparation of moto which is a thick liquid consisting of 

 steamed rice, water and koji in which the fungus transforms the starch 

 into sugar at o to 10 in a few days. Fermentation then starts sponta- 

 neously, alcohol being produced by the action of several yeasts and lactic 

 acid by bacteria, both present accidentally. In about two weeks the 

 moto is ready. The last stage is the principal fermentation which occurs 

 on mixing together steamed rice, koji, moto and water. This requires two 

 weeks. The liquid is then separated, cleared and stored. It contains a 

 considerable amount of alcohol and can be kept and aged like wine. 



POMBE is a kind of beer made in Africa from millet seed by sprouting 

 to saccharify the starch and subsequent spontaneous fermentation in 

 water. It is interesting as the source of the genus Schizosaccharomyces 

 which appears to take the main part in the fermentation. 



GINGER BEER is an acid, slightly alcoholic beverage made by the 

 fermentation of a 10 to 20 per cent solution of sugar containing a few pieces 

 of ginger root. The fermentation is induced by adding small pieces of the 

 so-called ginger-beer plant which consists of Bact. vermiforme and S. 

 pyriformis. The bacteria form a thick gelatinous sheath and seems to 

 live symbiotically with the yeast, each developing best in the presence of 

 the other. 



DISTILLED ALCOHOL. 



INTRODUCTION. 



USES AND SOURCES OF ALCOHOL. Distilled alcohol is used as a 

 beverage and a medicine or for innumerable purposes in the arts and 

 industries. Certain methods and sources employed for the latter pur- 

 poses are inadmissible for the former. 



