DURATION OF STOMACH-DIGESTION. 349 



found to contain the same inorganic constituents which existed in the nitrogenized prin- 

 ciples from which they are formed. 



Some discussion has arisen with regard to the action of the fluids of the stomach upon 

 the phosphate and the carbonate of lime, salts which are considered nearly if not en- 

 tirely insoluble. The action upon these principles is interesting, as they are essential 

 constituents of the osseous tissues. Observations in both natural and artificial digestion 

 have shown that the calcareous constituents of bone are, to a certain extent, dissolved 

 in the gastric juice. Bones are digested to a considerable extent in the stomach, although 

 the greater part passes through the alimentary canal and is discharged unchanged in the 

 faeces. Beaumont has shown this to be true in the human subject by experiments which 

 he performed, out of the body, with gastric juice taken from St. Martin. In these ob- 

 servations, after a certain portion of the bone had been dissolved, the action was in- 

 creased by the addition of fresh gastric juice. In the natural process of digestion, the 

 solution of the calcareous elements of bone is more rapid than in artificial digestion, 

 from the fact that the juice is being continually absorbed and secreted anew by the mu- 

 cous membrane of the stomach. 



Duration of Stomach-Digestion. 



Now that the relative importance of the stomach and the small intestines in digestion 

 is more fully understood, less interest is attached to the length of time required for the 

 action of the gastric juice upon different articles of food than formerly, when the stom- 

 ach was regarded as the principal, if not the sole digestive organ. It was thought at 

 one time that the food was converted in the stomach into a pultaceous mass called chyme, 

 which passed into the intestine, where the assimilable portion, the chyle, was separated 

 and absorbed by the lacteals. Beaumont, in preparing the elaborate table which has 

 been so much quoted, conceived that the simple action of the gastric juice represented 

 the chief part of the digestive process; and that it was possible, from experiments with 

 this fluid, to ascertain the digestibility of different articles. From this point of view, he 

 regarded fatty substances, which are now known to be digested exclusively in the small 

 intestines, as requiring a very long time for their digestion. 



Understanding, as we do, that comparatively few articles, and these belonging exclu- 

 sively to the class of organic nitrogenized principles, are completely dissolved in the 

 stomach, it is evident that the length of time during which food remains in this organ, or 

 the time occupied in the solution of food by gastric juice, out of the body, does not rep- 

 resent the absolute digestibility of different articles. It is, nevertheless, an interesting and 

 an important question to ascertain, as nearly as possible, the duration of stomach-digestion. 



There has certainly never been presented so favorable an opportunity for determining 

 the duration of stomach-digestion as in the case of St. Martin. From a great number 

 of observations made on digestion in the stomach itself, Beaumont came to the con- 

 clusion that " the time ordinarily required for the disposal of a moderate meal of the 

 fibrous parts of meat, with bread, etc., is three to three and a half hours." The obser- 

 vations of Prof.. F. G. Smith, made upon St. Martin many years later, give two hours as 

 the longest time that aliments remained in the stomach. In a remarkable case of intes- 

 tinal fistula, reported by Prof. Busch, of Bonn, it was noted that food began to pass out 

 of the stomach into the intestines fifteen minutes after its ingestion and continued to 

 pass for three or four hours, until the stomach was emptied. 



Undoubtedly, the duration of stomach-digestion varies in different individuals and is 

 greatly dependent upon the kind and quantity of food taken, conditions of the nervous 

 system, exercise, etc. As a mere approximation, the average time that food remains in 

 the stomach after an ordinary meal may be stated to be from two to four hours. 



Digestibility of Different Aliments in the Stomach. We are indebted to Beaumont 

 for nearly all that is positively known regarding the facility with which different articles 



