METABOLISM IN THE STOMACH AND INTESTINES 609 



of regurgitated duodenal contents. The work of one of us seems to show 

 the large role played by the degree of tonicity of the ingested meal in 

 the ultimate condition of the gastric contents due to. the marked effect of 

 this tonicity upon the excretion from the stomach wall, hypertonic fluids 

 provoking a marked excretory response. While it would take us too far 

 afield to go into the subject deeply, reference must be made to the im- 

 portance of the physicochemical explanation of the origin of the free hydro- 

 chloric acid in determining the chlorid content, of the body in hyper- 

 chlorhydria and achlorhydria, and in cases where- excessive amounts of 

 sodium chloride are taken with the food, or where such intake is prac- 

 tically nil, with practically no influence upon the chloride content of the 

 body but with marked variations in the chloride of the urine. As regards 

 acidity, however, one of us has shown that there is no constant relation- 

 ship between that of the gastric juice and of the urine, while the recent 

 work of Stohl and King in determining gastric acidity in terms of ioniza- 

 tion or hydrogen-ion concentration has really added to our knowledge of 

 the relationship between acidity and peptic digestion. Although of im- 

 portance in our consideration of this subject, we must leave to works on 

 physiology the solution of other problems of importance in this field 

 the extent of protein digestion in the stomach ; the presence of antif erment 

 in gastric juice or in stomach wall as an explanation of the resistance of 

 the stomach to autodigestion ; whether pepsin or rennin are identical 

 although the weight of evidence is against this; the extent of fat diges- 

 tion in the stomach and the reversible action of iipase and other ferments 

 these and similar problems make one realize the complexity of the 

 digesting process, and the great possibilities, still in the main unsolved, of 

 variation in the minor details of metabolism, even if in the majority of 

 instances the major aspects may remain comparatively normal. 



Variations in diet, as seen in different digestive diseases, notably the 

 neuroses, carcinoma and, ulcer, the marked lessening or increase in 

 the intake of protein, of fats, of carbohydrates, of fluids and salts, if 

 persisted in for a long time, must also produce certain special meta- 

 bolic pictures, although as yet not studied in detail in reference to the 

 various digestive diseases. According to Howell, "in the stomach it is 

 possible that there may be absorption of the following substances, water, 

 salts, sugars and dextrins that may have been formed in the salivary di- 

 gestion or that may have been eaten as such, the proteoses or peptones 

 formed in the peptic digestion of proteins or albuminoids," and although 

 as a rule absorption does not take place readily in the stomach, variations 

 in the degree of absorption must modify the metabolism, if only tem- 

 porarily and in a minimal degree. The amount of hydrolysis of proteins, 

 for example, must vary within very wide limits in different, diseases of 

 the stomach, depending not only upon the diet, but upon the secretory and 

 motor activities of the stomach here an achylia with hypermotility, 



