440 DIGESTION. 



physiological secretion, but rather the transudation of a neutral or faintly 

 alkaline fluid. Certain acids, such as carbonic acid, neutral salts, meat 

 extracts, spices, and other bodies also belong to this group. The 

 reports on this subject are unfortunately very uncertain and contra- 

 dictory. 



The question as to how far the observations made by PAWLOW and 

 his school can be applied to man is of special interest. Many observa- 

 tions on this question have been collected 1 and they compare favorably 

 with the observations made upon dogs. Thus in man a psychic secre- 

 tion of gastric juice can also be brought about, and it has also been observed 

 that it can be stopped by emotions. As in dogs, so also in man, after 

 sham feeding, a secretion takes place after a pause, whose duration varies 

 in different cases. In some cases, as in dogs after meat feeding, the 

 pause was about five minutes. The chewing of indifferent bodies did not 

 affect the glands, while bodies acting upon the organs of smell and taste 

 had an exciting action. UMBER observed besides this, that after the 

 introduction of a nutritive enema into the rectum a secretion of gastric 

 juice was produced by reflex action. 



From these observations of HORNBORG and UMBER, as well as -from 

 some earlier observations of SHULE, TROLLER, RIEGEL, and ScHEUER, 2 

 we conclude that in man the psychic secretion is much less than that 

 produced by the introduction of food or bodies having a pleasant taste. 

 That the preparation of the. food in the mouth has an essential influence 

 upon the secretion is proven without doubt, but we are not agreed as to 

 how this action takes place. Certain experimenters consider the secreted 

 and swallowed saliva as the most essential factor in this action, while 

 others believe that the act of chewing, and still others that the chemical 

 action and the sense of taste, are the most important. 



In regard to the action of saliva HEMMETER finds that after the 

 extirpation of the salivary glands, the introduction into the stomach 

 of chewed food soaked with dog-saliva, has no special action upon the 

 secretion of juice. On the other hand FROUiN 3 observed that the intro- 

 duction of saliva into the large stomach of dogs acts favorably upon 

 the secretion in the small stomach (see p. 437), and the acidity as well 

 as the digestive activity of the juice is increased. This action does not 

 depend, according to FROUIN, upon the alkali of the saliva. 



The Qualitative and Quantitative Composition of the Gastric Juice. 

 The human gastric juice, which can seldom be obtained pure and free 



1 Hornborg, Maly's Jahresb., 33, 547; Umber, Berl. klin. Wochenschr., 1905; 

 ade and Latarjet, Compt. rend. soc. biol., 57; Kaznelson, Pfliiger's Arch., 118; 

 Bogen, ibid., 117; Bickel, Deutsch. med. Wochenschr., 32, and Maly's Jahresb., 36, 411. 



2 The literature may be found in Umber's work, 1. c. 



3 Compt. rend. soc. biol., 62. 



