VI PREFACE. 



This book thus appeals to chemists, botanists, and bio- 

 logists, likewise to those technologists who are engaged in 

 the fermentation industries. 



In the bibliographical list I have included all important 

 works of both the older and more recent literature which 

 are of interest to the scientist and technologist. 



ALFRED JORGENSEN. 



COPENHAGEN, May, 1893. 



