PREFACE TO THE FIRST EDITION 9 



julvances, rclVniiifi; tlic leader to llic special ti'enfise.s for llie jj;eiieral 

 and historical discussion.s. 



It is with the greatest pleasure tluit I acknowledge my indeljtedness 

 to manj^ colleagues in the University of Chicago, who have kindly read 

 the sections of my manuscript that touch upon theii-own special fields, 

 and whose criticism and advice have been of the greatest assistance; 

 their mimb(>r alone prevents my thanking them by name. Most par- 

 ticularl}', however, must I express my debt to my former instructor, 

 Professor Lafayette B. Mendel, of Yale University, whose kindly 

 criticism and suggestions have been of inestimable value. For con- 

 stant assistance in the preparation of the manuscript, and for the 

 revision of the bibliography', I am ind(>bted to mv wife. 



H. G. W. 



