vi FOREWORD 



the French language. It is sincerely hoped, however, that the rendition 

 of this book into the English language will in no way inhibit the 

 study of the French language that language in which Pasteur, 

 Bernard, Magendie, Berthelot, and others have published their classic 

 investigations. 



This English edition is based on Guilliermond's " Les Levures," 

 which was published in 1912, appearing as a volume in the section on 

 Cryptogamic Botany of Encyclopedic Scientifique. This series is edited 

 under the direction of Doctor Toulouse. To merely translate a 

 volume on a subject which is being developed as rapidly as the 

 yeasts would be entirely inadequate. Consequently with the collab- 

 oration of Professor Guilliermond, the translator has added much 

 new material which has been published since 1912. Without the 

 assistance of Professor Guilliermond, this could not have been done 

 as completely. The English edition may not, then, be regarded as a 

 mere translation of the last French edition. 



The rendition of a text from a foreign language into the English 

 language is beset with difficulties which are most clearly appreciated 

 by those who have performed similar pieces of work. In all cases 

 a literal translation has not been attempted; however, the opinions 

 of the original author have been given as closely as possible. It is 

 trusted that this English edition will make it easier for students to 

 pursue their study of these important microorganisms and for the 

 practitioner to more easily solve the problems with which he has to 

 cope. I owe many thanks to my colleagues, too numerous to men- 

 tion here, for expression of their advice at various times and for 

 their interest during the progress of the work. 



UNIVERSITY OF ILLINOIS FRED W. TANNER 



URBANA, ILLINOIS 

 June, 1919 



