PREFACE TO THE THIRD EDITION 



The rapid advances that are constantly being made in 

 bacteriological work demand frequent changes in directions 

 for laboratory practice. The subject-matter contained in this 

 elementary work has been readjusted to satisfy these require- 

 ments, a few exercises on new topics have been introduced, 

 and the methods given have been modified to better meet the 

 conditions of student laboratory work. Continued experience 

 has strengthened our former opinion that a laboratory guide 

 which outlines the work for each exercise and gives specific 

 instructions for the same is of great assistance to both student 

 and teacher. I desire to express my thanks and appreciation 

 to Mr. G. Franklin White and Mr. Walter E. King for many 

 valuable suggestions that have been incorporated in the recast- 

 ing of these exercises. V. A. M. 



Ithaca, N.Y. 

 November, 1904 



