PREFACE V1J 



Lack of time, however, prevented him from completing his share 

 of the work. Chapters I, II, and III were written by Dr. Pearse; 

 Chapters I and II were then revised jointly, and Chapter III was 

 completed by the present author alone. I wish to express my 

 gratitude to Dr. Pearse for allowing me to use the first three 

 chapters, for reading most of the remaining chapters, and for 

 many valuable criticisms during the preparation of the manu- 

 script. 



In an endeavor to make the text as nearly correct as pos- 

 sible, the author sent the various chapters to specialists on 

 the subject-matter treated therein. These gentlemen, how- 

 ever, are in no way responsible for any errors that may have 

 escaped notice. The author is grateful to Professor Jacob 

 Reighard for criticisms during the preparation of the work 

 and for reading Chapter XIV, to Professor S. J. Holmes for 

 reading the entire manuscript, to Rev. H. F. Hegner for read- 

 ing Chapters I-VIII, to Professor C. M. Child for reading 

 Chapters I-III, to Professor F. G. Novy and Dr. H. Hus for 

 reading Chapters IV-VI, to Dr. O. P. Dellinger for reading 

 Chapter IV, to Professor L. L. Woodruff for reading Chapter 

 V, to Professor T. H. Montgomery, Jr., for reading Chap- 

 ter VII, to Dr. E. R. Downing for reading Chapter VIII, to 

 Professor W. C. Curtis for reading Chapter IX, to Professor 

 J. Percy Moore for reading Chapter X, to Dr. A. E. Ortmann 

 for reading Chapter XI, to Dr. E. F. Phillips and Mr. Max 

 Peet for reading Chapter XII, and to Dr. A. G. Ruthven and 

 Dr. H. Hus for reading Chapter XIV. 



ROBERT W. HEGNER. 



