PREFACE TO THE AMERICAN EDITION. 



In presenting this the American edition of the well-known 

 and appreciated work of Doctors Muir and Ritchie, the en- 

 deavour has been made to add to the value of the book by 

 giving adequate expression to the best in American laboratory 

 methods and research, and, at the same time, to augment the 

 general scope of the work -without eliminating the personal 

 impress of the authors. Therefore occasional alterations and 

 additions of greater or lesser magnitude have been made 

 throughout the book in general, but more especially in Chap- 

 ters II, III, IV, XV, and XVII ; whilst the chapter on Fungi, 

 deleted from the last English edition, has been retained and 

 enlarged. The section of the Manual dealing with the bibli- 

 ography has also been extended to cover as far as possible the 

 advances in work made in this country and abroad. 



Some photographic reproductions and a few engravings of 

 apparatus have been added to those of the English edition, for 

 which hearty thanks is due Doctors A. C. Abbott, T. C. Gil- 

 christ, and Charles Potter, and Messrs. Charles Lentz & Sons, 

 and W. B. Saunders & Co. for their kindness in furnishing the 

 same. 



The Editor takes this opportunity of expressing his in- 

 debtedness to Professor William H. Welch for many helpful 

 suggestions in the preparation of the edition. 



N. MAC L. H. 



The Johns Hopkins University, 



Baltimore, Maryland, 



November, 1902. 



