PREFACE TO THE SEVENTH EDITION 



THIS book has undergone a complete revision and many 

 of the chapters have been rewritten in their entirety. Those 

 which relate to immunity and infection have been carefully 

 edited by Dr. Paul G. Weston, Pathologist at the State 

 Hospital, Warren, Pa., who has also furnished the article 

 on the Wassermann reaction. The author is likewise in- 

 debted to him for valuable aid in other portions of the re- 

 vision. 



The author realizes that compends of this nature must 

 necessarily suffer in comparison with the larger and more 

 elaborate works, and he trusts that the reviewers will bear 

 this in mind in their criticisms. 



When this book first appeared in 1891 it was one of the 

 first American publications on the subject, and only a few 

 text-books had been issued in other countries. Although 

 since then a great many excellent treatises have appeared, 

 there still remains a place for this compend, and hence this 

 new edition. The author hopes that he has succeeded in incor- 

 porating all the newer established facts in bacteriology and 

 in eliminating all that is obsolete and no longer in use. 



M. V. BALL. 

 WARREN, PA., December, 1913. 



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