VI INTRODUCTION 



available for students who have the desire to take it and 

 our experience at two medical schools has taught us that there 

 are always a good many who do. 



The little volume has been compiled in the first place for 

 our own convenience from the protocols given to our students. 

 If incidentally it is of service to others in planning similar 

 courses, or to laboratory workers in repeating experiments, 

 we shall be pleased. The book as it stands is, of course, not 

 a manual of immunity. The course should follow or be syn- 

 chronous with lectures, reading, and demonstrations on the 

 principles of infection and immunity. In our own work the 

 course is offered to students who have had work in general 

 Bacteriology and have taken the lecture course on Infection 

 and Resistance, and reading is assigned in the textbook on 

 this subject. 



Since the manual has grown out of the course after some 

 four years of experimentation and adaptation to classroom pos- 

 sibilities, it in no way represents an " ideal " formula but de- 

 scribes only work actually done with students. For this reason 

 we have often simplified the experiments in a way which would 

 be undesirable in actual research work. But we have not done 

 this at the expense of exactitude. Thus we have in many 

 cases adapted the technique to the possibilities of a single after- 

 noon with a class not yet fully trained. In order to facilitate 

 the giving of such a course by other teachers we have added 

 a time schedule of the whole course, and have given in each 

 exercise a list of the materials needed. 



