IV PREFACE. 



immunity have been revised so as to conform with the 

 recent views on the subject as based upon the funda- 

 mental researches of Ehrlich and Morgenroth, Bordet, 

 Buchner, and others. 



Of necessity, the book has increased a little in size, 

 but it is believed that this will in no way lessen its use- 

 fulness, and it is hoped will in no wise detract from the 

 cordial reception that has hitherto been accorded it. 



A. C. A. 



Philadelphia, March, 1902. 



