INTRODUCTION TO THE SECOND 

 EDITION 



The continued and growing demand for "Microbiology" has caused 

 the contributors to undertake a thorough revision. In this they have 

 been guided by the recent developments in this branch of science, 

 and also by a desire to adjust and rearrange in the light of constructive 

 suggestions and criticisms. 



The primary purpose of this text-book is to place in the hands of 

 college students an elementary technical treatise of the subject matter 

 included. No effort has been made to review or cite literature, for to 

 do either would expand the volume beyond useful limits. To provide 

 an introductory text-book mainly for recitations, or for a supplement 

 to lecture or laboratory courses, is about all that can be satisfactorily 

 comprehended in a single project. 



The cytological aspect of microbiology has seemed to us to deserve 

 some emphasis, for it has become quite definite and has been suggest- 

 ively indicating much of real value in connection with the active life 

 processes of the cell and microbic activities in agriculture, medicine 

 and wherever microbiology is applicable. 



The significance of "Intestinal Microbiology" has required a short 

 chapter for its proper presentation. 



It has also been found desirable to treat the microbial diseases of 

 insects, a growing subject, in a distinct chapter. 



The study of microorganisms flounders in a fog of unsettled ideas 

 for a proper designation. Whether it should be called Protistology, 

 Microbiology, Bacteriology, Mycology, or something else must be left 

 for the future to determine. 



Charles E. Marshall, Editor. 

 Amherst, Massachusetts. 



vu 



