PREFACE TO THE FIRST EDITION. ix 



In relation to the grouping of the infectious 

 diseases adopfed in Part III, attention is called 

 to the explanatory paragraph, page 398. 



It will be noted that a bibliography of the sub- 

 ject of immunity has not been added, and this 

 needs no explanation to one who is conscious of 

 the massive proportions of the literature. A crit- 

 ical analysis of the entire literature, which would 

 not have been in harmony with the endeavor to 

 present the topics briefly and clearly, and which 

 would have made detailed references essential, has 

 not been attempted. The most recent literature 

 on the various subjects is accessible through the 

 Index Medic U3, or the index prepared semi- 

 annually by The Journal of the American Medical 

 Association. 



The index at the close of this volume serves as 

 a glossary of terms, the explanations of which may 

 be found on the pages referred to. 



H. T. ElCKETTS. 



CHICAGO, February, 1906. 



