iv PREFACE. 



More than any other one measure, this practice has seemed of value in 

 giving the student confidence in his powers of observation and reliance 

 on his application of methods. 



It has come to be a question as to how much of the general subject shall 

 be taught in the brief course permissible in the crowded medical curriculum. 

 In the earlier days of his teaching the writer paid more attention to the 

 detailed characteristics of the important bacteria, especially the pathogens, 

 than to technical work; this more because of the lack of a satisfactory 

 system of classification of the bacteria and a chaotic condition of the gen- 

 eral study than because he failed to appreciate the need of such system. 

 In the more recent years, however, much advance has been made in these 

 lines, and it is more in harmony with the purpose of education that the 

 student should be taught in the laboratory the methods of demonstration 

 of bacterial characters and properties, and a proper manner of investiga- 

 tion and observation, than that he should devote his time and attention 

 to isolated facts which in many instances are better brought to his com- 

 prehension in connection with his work in medicine or surgery. The writer 

 has endeavored in selection of the illustrative work to embody the more 

 important points which clinical study demands, but in no other way 

 than as important illustrations. Such special points cannot, of course, 

 be too often brought forward or too much impressed, but they will prob- 

 ably be best remembered from their relations to clinical instruction. 



There are a number of works of a systematic character adapted to 

 bacterial determination and identification, although the perfect system of 

 bacteriologic classification is probably far in the future; during the past 

 year the writer has become familiar with the many excellent features of 

 Chester's Determinative Bacteriology, and in the arrangement of the follow- 

 ing pages the latter was in mind as a suitable reference book for the student 

 in working out the identification of unknown species and for inquiry as to 

 the important cultural characteristics of known bacteria. The admirable 

 work of Neumann and Lehmann in its American edition is equally to be 

 commended, particularly in its technical and descriptive portions, for class 

 purposes. 



As outlined, the entire series of exercises embodied in the following 

 pages may be carried out in eight or nine weeks, each student working at 

 least ten hours each week. It will be necessary, however, that the in- 

 structor inaugurate such work as will require time for its completion before 

 the completion of preceding exercises; and it is well to have the student 

 understand that the order of work corresponds rather with the end than 

 with the beginning of each task. 



There is, of course, nothing original in the book either in the matter or 



