PREFACE TO THE SECOND ENGLISH EDITION. 



The necessity for a second English edition has arisen after an interval 

 of a year. It is a source of satisfaction to note the apparent general 

 approval and demand which this small book on " Immunity" has fulfilled. 

 The credit to Dr. Citron is well deserving. The text of the new English 

 publication has been carefully reviewed and minor changes made, but it 

 follows closely that of the German with its important additions. Like 

 in the first English edition, however, so also in the second, topics of more 

 recent development, treated only very slightly or not at all in the German, 

 have been enlarged or inserted: gonococcus and typhoid complement 

 fixation tests, agglutination and hemolysis tests for transfusion, prophy- 

 lactic typhoid inoculation, etc. Friendly criticism to discuss some sub- 

 jects with more detail has been gladly met and corrected, so that a be- 

 ginner may have no greater difficulty than is only natural. It is hoped 

 that this English edition will meet with the same approbation which I 

 am happy to say has been accorded the former one. 



A. L. GARBAT. 



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