Vlll PREFACE TO FIFTH EDITION 



author believes might well have been omitted have been retained in 

 small type. The author believes that it is preferable that each indi- 

 vidual instructor shall use his own judgment as to which tests and 

 methods he will omit from his course. For this reason, in connection 

 with certain quantitative procedures more than a single approved 

 method has been given. 



Thirty-five new illustrations have been incorporated. 



The author takes pleasure in acknowledging the important part 

 played by Dr. Olaf Bergeim in the preparation of this new edition. 

 Dr. Bergeim's suggestions and assistance have been invaluable in 

 connection with all phases of the revision, as well as in the preparation 

 of new material for introduction. To Dr. Martin E. Rehfuss the 

 author is indebted for the drawings of the microscopical constituents 

 of the feces and gastric contents and the curves which are introduced 

 in the Chapter on Gastric Analysis, as well as for timely suggestions 

 as to certain clinical aspects of fecal and gastric analysis. Other 

 members of the author's staff who have aided in certain phases of the 

 revision are Drs. H. Rodell Fishback, Melvin A. Saylor and Clarence A. 

 Smith. 



To Professors Lafayette B. Mendel, Paul E. Howe, Marshall P. 

 Cram, A. P. Sy and J. C. Blake, the author is also indebted for helpful 

 suggestions, and to Professors William J. Gies and Walter Jones for 

 permission to insert selected experiments from their laboratory direc- 

 tions. The author is under further obligation to Professor Jones for 

 crystals of hypoxanthine chloride and guanine chloride from which 

 were prepared the microphotographs appearing in the Chapter on 

 Nucleic Acids and Nucleoproteins. He also wishes to thank Professor 

 Chester C. Fowler for permission to insert unpublished material. 



The author is very appreciative of the unfailing courtesy and con- 

 sideration of the publishing house of P. Blakiston's Son & Co.; the 

 timely suggestions of Mr. C. V. Brownlow, Mr. I. A. Hagy and Mr. 

 Horace G. White have been very helpful. 



