PREFACE 



This book comprises a course of lectures and laboratory work 

 ■given to graduate and advanced medical students in the Uni- 

 versity of Minnesota. The need for special teaching in the ap- 

 plication of the simpler aspects of physical chemistry to biology 

 was first realized by the author while attempting to teach physics 

 and physiology to the same group of college students in 1906. 

 A collection of abstracts of papers on the subject was commenced 

 but interrupted by various affairs, especially the change to med- 

 ical teaching. It became evident, however, that even medical 

 students with a crowded curriculum would do well to devote any 

 available time to this subject if they expect to do any research 

 or read current medical literature. 



The purpose of the book is not to go far into physical chem- 

 istry but to develop a tool for physiological research. Lengthy 

 discussions of debated questions are avoided by tentatively ac- 

 cepting the hypothesis which fits the most facts, until a better one 

 appears. For further discussion of any subject the reader is 

 referred to the literature list and index. For facts, however, 

 he is referred to nature. It is not to be hoped that theories 

 should coincide exactly with data available at present. Even in 

 the most exact branches of chemistry the atomic weight deter- 

 minations, for instance, do not exactly coincide with the values 

 calculated from the atomic numbers, and there seems to be some 

 doubt as to whether lead is one element or several. How much 

 more uncertainty there should be about physiology, where de- 

 terminations are vitiated by the great variability of the material 

 and its physiological states. 



The literature list was compiled from abstracts made in various 

 libraries during the last ten years in addition to published ab- 

 stracts and summaries. In some cases only part of a paper or 

 the summary was read. Following the date is the gist of some 

 data to which it is desired to call attention, or some conclusion 

 which the data apparently justify but which may not be ac- 



