PART 1. INTRODUCTION. 



The greatest strides in medicine during the past decade have unquestionably 

 been made in that particular branch of science designated as preventive medi- 

 cine. Efforts on the part of hygienists, aided by chemists and bacteriologists, 

 to have mankind live normal, clean lives, to breathe pure air, drink pure water, 

 and partake of clean and suitable foods, have been productive of most astonish- 

 ing results. These efforts have resulted in a marked influence on the inroads 

 of disease and have, perhaps, more than any other one factor, been instrumental 

 in emphasizing just what is " normal " in life. Previously little attention was 

 paid to ventilation, water-supplies, and food, other than spasmodic efforts to 

 better existing conditions when some epidemic necessitated such reform; to-day 

 the education of the people has so steadily progressed that a much more general 

 interest is taken in hygiene and the normal in life, and it is no longer customary 

 to wait until some dire calamity makes imperative an examination of existing 

 conditions and their influence on those factors which play so important a role 

 in the normal, healthy life of man. 



Accompanying the general interest in affairs of health is found a noticeable 

 advance in our knowledge of physiological processes, particularly those proc- 

 esses pertaining to the use and digestion of food. Our knowledge of the chem- 

 istry and physiology of digestion was, in earlier days, based in large part upon 

 the observations of William Beaumont 1 on Alexis St. Martin. These were 

 surprisingly accurate, considering the knowledge of physiology at that time. 

 Now, thanks to the researches of Pawlow 2 and Cannon, 3 these subjects have 

 been made much clearer. The chemistry of food and the general processes of 

 the nutrition of man have attracted the attention of many European scientists 

 for a number of years, and in our own country wonderful advances in the study 

 of nutrition have been made by Atwater.* 



All of these researches contribute greatly to our knowledge of physiology 

 and thereby, indirectly at least, supplement the investigations on preventive 



1 William Beaumont, Experiments and observations on the gastric juice and the 

 physiology of digestion, Plattsburgh, 1833. 



2 Pawlow, Ergebnisse der Physiologie, 1902, Biochemie, p. 277; Arbeit der Ver- 

 dauungsdrusen, Wiesbaden, 1898. 



3 Cannon, W. B., Numerous papers in the American Journal of Physiology, 1898- 

 1909. 



4 Atwater, Numerous papers, particularly in the bulletins of the United States 

 Department of Agriculture, 1895-1903. 



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