LECTURE VI. 



THE CHEMICAL STIMULI OF THE NERVOUS ME- 

 CHANISM OF THE GASTRIC GLANDS : THE 

 MINIATURE STOMACH A RELIABLE METHOD OF 

 COMPARISON SEAT OF ACTION OF THE CHEMI- 

 CAL STIMULIHISTORICAL. 



Water as an excitant of the gastric glands The effects of watery 

 solutions of the ash of flesh, of sodium chloride, of soda, and of hydro- 

 chloric acid on the gastric glands. Solutions of egg-white are ineffec- 

 tive as excitants Meat broth, meat juice, and solutions of Liebig's Extract 

 are reliable exciting agencies Neither starch nor fat is able to call 

 forth a gastric secretion Chemical excitants are also produced in the 

 peptic digestion of proteids Starch influences the quality of the juice by 

 augmenting its content of pepsin. Fat inhibits the work of the gastric 

 glands, both from a quantitative and from a qualitative point of view 

 The miniature cul-dc-sac furnishes a true picture of the work of the large 

 stomach. The chemical excitants of the nervous mechanism of the gastric 

 glands have their seat of action at the surface of the mucous membrane. 

 The investigations of Blondlot and of Heidenhain on the secretory work of 

 the stomach. 



GENTLEMEN, In the last lecture we had settled (1) that psychic exci- 

 tation, notwithstanding its importance, is not the only source of gastric 

 secretion ; (2) that the mechanical properties of the food in themselves 

 are unable to call forth a direct secretion of gastric juice. In order to 

 answer the question as to what circumstances within the cavity of 

 the stomach may act as stimuli to secretion, we must turn to the 

 chemical properties of the food. Our experiments on this point have 

 for the :uust part been performed on dogs with isolated miniature 

 stomachs. The fluid substances to be tested were at first passed into 

 the stomach by means of a sound. Later, when a second fistula was 

 opened in the main stomach, they were introduced directly through it. 

 Obviously the latter method is incomparably the better, since it con- 

 tains fewer sources of error and is less troublesome for the observer. 

 The introduction of the sound is unpleasant to the animal, and may 



