PREFACE TO THE SECOND EDITION. 



ALTHOUGH there has been no lack of works on bacteri- 

 ology, it seemed to the writer that there was still a field 

 open for one which sought to give the portions essential to 

 medical science in a concise manner. It is gratifying, there- 

 fore, that the first edition of this little book should have been 

 exhausted so soon. 



Whether wisely or not, it is a fact that many medical 

 schools require their students to absorb an amount of 

 knowledge that taxes the brain to the utmost. While such 

 conditions remain, the need is urgent for presenting what 

 is taught in the accessory branches in as condensed a form 

 as is consistent with a clear understanding of their great 

 fundamental principles. It is mastery of such principles, 

 after all, which is the object of a course in bacteriology, 

 for they are essential to a correct understanding of most of 

 the other branches. After that has been accomplished, 

 (including the applications of bacteriology to diagnosis), 

 it must be admitted that other branches deserve a larger 

 amount of the student's time. This may be said without 

 meaning to minimize the importance of bacteriology in the 

 training of a physician. In the opinion of the writer it is 

 neither possible nor desirable that every graduate should 

 be a trained bacteriologist. However, no instructor can 

 hope to bring the principles above mentioned home to his 

 classes except by laboratory work. Very little attempt 

 has been made to outline the program of a laboratory 

 course, as that will always need to be planned according 

 to the circumstances under which it is given. 



