vi PREFACE 



The charts of the various organisms furnish a most satisfactory 

 means for recording the observations made during the study of a 

 germ and are especially convenient for reference. 



Blank pages have been left for notes and drawing with the 

 idea that notes in permanent form are the only ones of value to 

 the student in subsequent years. 



Eeferences have been made to the leading text-books and occa- 

 sionally to original sources. It is expected that the student will 

 make constant use of these references. 



My acknowledgments are due to my colleagues, Professor C. A. 

 Fuller and Miss Vermillion Armstrong. 



W. D. FROST. 



Madison, Wis., January, 1911. 



