PEEFACE. 



THE present book gives an account of the morphology and 

 biology of the micro-organisms of fermentation, and it thus 

 forms a complement to the text-books which treat mainly of 

 the chemical side of the subject. 



I have attempted to give a general review of all the 

 knowledge we possess in this field, and have described the 

 various methods of investigation which in the course of time 

 have proved of importance. 



In discussing the organisms of fermentation and their 

 relation to industry, there are two names which more 

 especially attract our attention, namely, Pasteur in the older 

 literature, and Hansen in the more recent literature of our 

 subject. Since this book is intended to give an account of 

 the present stand-point of the science, it is evident that the 

 investigations from the Carlsberg Laboratory must occupy 

 an important position. In Chapters V. and VI. will be found 

 an accurate description of Hansen s theoretical investigations 

 on the alcoholic yeasts, of his methods for the pure cultivation 

 and analysis of yeast ; likewise an account of the use of pure 

 yeast on a manufacturing scale, and of the results obtained 

 with it in breweries, distilleries, and pressed yeast factories, 

 and in the preparation of wines from the grape and other 

 fruits. 



