PKEFACE 13 



The section on bibliography has been compiled with particular care, 

 as have also the various indices, 



I wish gratefully to acknowledge the assistance of many members 

 of the staff in bacteriology at the Iowa State College, especially Miss 

 Clarissa Clark, Mrs. C. H. Werkman, Miss Ruth Confare, Mr. J. C. 

 Weldin and Dr. Max Levine. For interest and assistance in biblio- 

 graphic details acknowledgment is due Miss Margaret Brown and Prof. 

 C. H. Brown of the library of Iowa State College. 





