DIGESTION 239 



A consideration of these facts shows that the long- 

 established custom of beginning dinner with soup is 

 justified, and should also be a guide to us in selecting 

 suitable foods for administration by forced feeding. 



On the other hand, some foods, such as bread, starch, 

 and white of egg, do not excite a flow of juice at all, 

 whilst fat tends actively to restrain the secretory activity. 

 The former foods are therefore indicated where one 

 wishes to excite gastric secretion as little as possible, 

 whilst the administration of fatty substances is justified 

 in cases in which secretion is already excessive. Some 

 drugs, such as bicarbonate of soda and bismuth, appear 

 also to have the power of inhibiting the secretion. 



The proof which physiology has now furnished that 

 gastric secretion is entirely dependent upon nervous in- 

 fluences, and is not the result of mechanical stimulation 

 by the food, is of great interest to practical medicine, 

 for it makes it easier to understand the large part which 

 disturbances of the nervous system play in the pro- 

 duction of functional dyspepsia. 



The gastric juice, then, which is required for the 

 digestion of an ordinary meal is the result of the com- 

 bined action of these two sorts of stimulus, and the flow 

 of it begins even before food has actually entered the 

 stomach, and continues actively during the first hour or 

 so of digestion, and then undergoes a gradual decline. 

 The composition of the juice appears to be fairly con- 

 stant in the same individual, but varies in different 

 persons, even although the food be the same. In other 

 words, when more hydrochloric acid is required it is 

 obtained by increasing the total quantity of juice 



