

PREFACE. 



THEjfirst edition of this work was issued in the form of a 

 text-book in 1886. It was the first attempt to express the 

 biological significance of the science of fermentation and of 

 the fermentation industry, a field where the chemical point 

 of view had hitherto prevailed. 



I was induced to give this form to my work by the fact 

 that in 1881 I had established an institute in which my first 

 aim was to treat the problems of the fermentation industries 

 from a micro-biological point of view. This necessitated a 

 short course for technologists and chemists who wished to 

 study the science of fermentation on new lines, and as both 

 older and younger students were attracted to my laboratory, 

 the subject-matter had to be arranged so that the book could 

 serve as a guide, even to those who had no special preliminary 

 knowledge. During my co-operation with E. C. Hansen in 

 that early period, the principles of the practical application 

 of pure cultures were broadly outlined, and accordingly 

 an explanation of the principles underlying the resulting 

 technical reforms formed the essence of the treatise. The new 

 editions which appeared in rapid succession, showed that the 

 attempt had been successful. At the same time, I had the 

 good fortune to introduce into breweries in many countries 

 properly selected pure cultures of bottom yeasts, following 

 the precedent of E. C. Hansen, who shortly before had intro- 

 duced similar yeasts into the Carlsberg Brewery in Copen- 

 hagen. At this early stage, I successively described pure 

 cultures of yeast types which are used in other branches of 

 the fermentation industry, and I introduced them into top- 

 fermentation breweries, as well as into distilleries, yeast fac- 

 tories, fruit-wine factories, etc. Thus a beginning was made in 

 the application of this new principle to new fields of industry. 

 Consequently, to keep pace with these developments, together 

 with the results of research in the science of fermentation, my 

 book had to be so largely modified that each new edition 

 became to some extent a new book, whilst the growing mass 

 of material considerably increased the size of the book. Having 

 to keep within certain limits, I was reluctantly compelled to 



