PREFACE 



The considerations which led the writer to add this 

 laboratory guide of bacteriology to the number of such 

 guides already in existence were of various nature and 

 may be briefly set forth here. 



Probably no branch of biological science has advanced 

 so rapidly during the past few years as the science of 

 bacteriology, and it is difficult even for an active labora- 

 tory worker to keep abreast of this advance. A text- 

 book or guide fixes the status of the science at the time 

 of its writing, but almost before it leaves the press it 

 becomes antiquated. Revisions, corrections, and addi- 

 tions are necessary at short intervals in order to keep a 

 publication of this kind approximately up to date. There 

 is therefore, almost at any given moment room for a new 

 pubhcation to fill the want of a progressive instructor for 

 a guide that gives the latest accepted rules and practices 

 of the laboratory. The value of such a publication will 

 be enhanced by a plan and arrangement of sufficient 

 flexibility and latitude to allow the instructor and the 

 student to enter such additions and corrections as serve 

 to bridge over the time between editions. 



Medical students entering on a course in bacteriology 

 often have had too little previous laboratory training in 

 methods of precision. It is a matter of importance for 

 the instructor to put himself in the attitude of mind of the 

 student and to try to appreciate his difficulties in under- 

 standing details. Many of the pieces of apparatus 

 employed in a bacteriological laboratory are novel even 



