236 APPLIED PHYSIOLOGY 



it is in consequence of such direct stimulation that irri- 

 tating and unsuitable foods may set up gastric catarrh. 



The stimuli which can excite a flow of juice are either 

 (1) psychical or (2) chemical. The mere sight or smell 

 of food, or the agreeable taste of it in the mouth, given 

 the presence of appetite, is sufficient to start an active 

 flow of juice whilst the stomach is still empty. It is not 

 the mere mechanical act of chewing, but the relish of 

 the food which originates the reflex. Hornborg,* for 

 instance, has observed in the case of a boy with a gastric 

 fistula and occlusion of the oesophagus that the chewing 

 of indifferent substances, such as indiarubber, failed to 

 cause gastric secretion. 



The juice thus poured out to which Pawlow has 

 given the name of ' appetite juice ' is of great value 

 in starting the process of digestion, and it has been 

 suggested that the favourable results in some cases of 

 dyspepsia of giving frequent small meals rather than 

 a larger quantity of food at longer intervals are to be 

 attributed to the greater quantity of 'appetite juice' which 

 is thus obtained. Be this as it may, the realization of 

 the value of the ' appetite juice ' is of the first importance 

 to the physician, and should encourage him to make 

 every effort to promote the appetite of patients with 

 feeble digestion by attention to the aesthetic qualities 

 and flavour of their food, as well as by the administration 

 of exciters of appetite such as bitters. t 



* SJcandinav. Arcliiv f. PhysioL, 1904, xv. 248. 



t Seeing that bitters promote a flow of gastric juice by acting 

 upon the nerves of taste, they should always be administered in 

 solution if their full effect is to be obtained, and not swallowed 

 in the form of a tabloid, capsule, or pill. 



