6 PREFACE 



minor importance, are essential. The material gained in the course 

 of this process of elimination, merits no further abridgment and the 

 student should acquire a thorough working knowledge of it. In re- 

 cent years our physiological literature has been enriched by a number 

 of very admirable text-books upon physiological chemistry, such as 

 those of Hammarsten, Mathews, Mcleod, Bayliss, Oppenheimer, Lusk, 

 Rubner, and Gautier. I am deeply sensible of my obligations to these 

 authors for the material I have gathered from their writings. But, 

 since this field has been so minutely covered by them, I have not 

 attempted in the present book to give anything further than a general 

 story of these events. The student should be in possession of at least 

 one of these treatises as a means of gathering his chemical knowledge 

 from a more thorough and detailed source than I could possibly present. 

 It has been my endeavor to remain as much as possible on the mechani- 

 cal or physical side of Physiology without, however, completely elimi- 

 nating its chemical aspect. It is certainly my ardent desire to keep 

 Biological Chemistry within the fold of Physiology in a relationship 

 most beneficial to both sciences. 



Being convinced that diagrams and simple sketches are of inesti- 

 mable value to the student, I have inserted in the present book a large 

 number of them. Some of these may lay claim to a certain originality, 

 while others are mere modifications of earlier sketches of a similar 

 kind. For the latter I am indebted to the authors and publishers of 

 Quain's Anatomy, Herrick's "Elements of Neurology," Schafer's "Es- 

 sentials of Histology," Starling's "Human Physiology," and Ho well's 

 "Text-book of Physiology." I am also very glad to acknowledge my 

 obligation to the publishers of Verworn's "Allgemeine Physiologic," 

 Winterstein's "Handbuch der vergleichenden Physiologic," Nagel's 

 "Handbuch der Physiologic," Luciani's "Fisiologia Humana," and 

 Opperiheimer's "Handbuch der Biochemie." The chemical subject 

 matter of this book has been kept in close conformity to this 

 standard work, while the introductory remarks pertaining to the 

 structural and functional aspects of the cell, have been closely allied 

 to the well-known treatises of Wilson and Verworn. 



R. BURTON-OPITZ. 

 COLUMBIA UNIVERSITY, 

 NEW YORK CITY, 



