100 THE WORK OF THE DIGESTIVE GLANDS. 



of bread had no stronger stimulating influence on the gastric glands 

 than equal quantities of water. 



Are we then to rest content with these results ? Do they furnish a 

 complete explanation of the progress of secretion in normal digestion ? 

 Obviously, No ! In the case of flesh diet the condition of matters 

 is tolerably clear. The secretion here is partly set up by psychic 

 effect and partly by chemical substances peculiar to flesh. With 

 bread and boiled-egg albumen the case is otherwise. Their rela- 

 tions are by no means clear. Only the initial secretory period, which 

 has its origin in the psychic effect, is explained ; the further periods, 

 which count from the end of the first three or four hours, are dependent 

 upon an iinknown process, since only a portion of the secreted juice 

 can be accounted for by conditions at present revealed to us. To 

 make the importance of these questions more manifest, I beg you to 

 compare the experiments with starch jelly, in the one case eaten, in 

 the other directly brought into the stomach. As I told you previously, 

 starch paste, when directly introduced, calls forth no secretion worth 

 mentioning, while, if eaten by the animal, a secretion lasting two to 

 three hours is set up. A careful consideration of this experiment 

 discloses its meaning at once. The juice poured out in the second 

 case exactly corresponds to the " psychic " secretion, the energy of 

 which we have already learned in the sham feeding experiment. This 

 correspondence, however, no longer obtains when bread or boiled- 

 egg albumen is eaten. Not more than one-half or even one-third of 

 the juice secreted in these cases can be ascribed to the psychic effect. 

 The source of the remaining portions remains as yet undiscovered. 

 That, as a matter of fact, some other cause, some other excitant, must 

 exist, follows from this, namely, that the juice of the second or third 

 hour after the eating of the egg-albumen possesses no specially strong 

 digestive power, while the psychic juice, as already stated, is of the 

 most active kind. The most natural conclusion is, that during the 

 elaboration of bread and egg-albumen by the psychic juice, a 

 chemical agency comes into existence early in digestion, which sets 

 the neuro-secretory mechanism of the stomach into activity. Probably 

 it is a digestive product identical or similar to the substance which 

 nlays the role of exciter in the case of flesh. 



In support of this explanation we are able to bring forward 

 experimental data. If one obtains the fluid digestive products 

 from the stomach of a dog which has eaten egg-albumen, and 

 injects them directly into the main stomach of a dog with an isolated 

 miniature cavity, a much stronger and more constant secretory effect is 

 produced than is yielded by a like quantity of water or fluid egg- 

 albumen (Dr. Lobassoff). The formation of this product cannot, 



