PERIOD OF OCCURRENCE AND IMPORTANCE OF THE PSYCHIC OR APPETITE JUICE IN THE SECRETORY WORK OF THE STOMACH—THE INEFFICIENCY OF MECHANICAL STIMULATION OF THE NERVOUS APPARATUS OF THE GASTRIC GLANDS
The psychic secretion is the normal commencement, in the majority of cases, of secretory activity on the part of the gastric glands. If the meal be subdivided and administered at intervals, the psychic juice appears each time—Demonstration of “appetite juice” in a dog with an isolated gastric cul-de-sac. The work of the gastric glands if appetite juice be avoided by introducing food through a gastric fistula unperceived by the animal—Digestion of flesh by the stomach with and without sham feeding—Duration of the secretory influence of sham feeding—After the cessation of the psychic effect, how is the secretory work of the stomach maintained?—Experiments to prove the ineffectiveness of mechanical stimulation: excitation of the mucous membrane by means of a glass rod, a feather, a puff of sand, and by rhythmic dilatation of an india-rubber ball—Contact between the food and the stomach-wall may indirectly call the activity of the glands into play by awakening or increasing the desire for food.
Gentlemen,—On the last occasion we made ourselves acquainted with the first normal impulse which, in the natural course of events, calls into activity the innervation apparatus of the gastric glands. This impulse is a mental one, and consists in a passionate longing for food, that which in every-day life, and in the practice of the physician, is called “appetite,” and which everybody, both medical and lay, endeavours carefully to promote. We may now venture to say explicitly, APPETITE IS JUICE, a fact which at once displays the pre-eminent importance of the sensation. Medical science endeavours to assist the debilitated stomach by introducing the active constituent of gastric juice—pepsin—from without, or by prescribing other remedies believed to promote its secretion. It is, however, of interest to follow our experimental investigation still farther. What position is to be assigned to the “psychic” or “appetite-juice”[30] in the course of normal gastric digestion? Is any definite rôle to be attributed to it? What course does gastric digestion take when it is absent? Fortunately to all these important questions satisfactory answers are forthcoming by experiment. We have only to regret that these answers come so late.
Let us recall to memory how the secretion of gastric juice proceeded after feeding with flesh or bread in the case of our dog with the isolated miniature stomach. The following are the quantities and digestive capabilities of the first two hourly portions of juice after the administration of 200 grams of flesh or bread (experiments by Dr. Chigin):
| Hour. | Flesh. | Bread. | ||
|---|---|---|---|---|
| Quantity of juice. | Digestive power. | Quantity of juice. | Digestive of juice. | |
| c.c. | mm. | c.c. | mm. | |
| 1st | 12.4 c.c. | 5.43 mm. | 13.4 c.c. | 5.37 mm. |
| 2nd | 13.5 | 3.63 | >7.4” | 6.50 |
You see at once that the secretion of the first hour is identical in the two cases both as regards quantity and digestive power, and only in the second is the secretory work differentiated according to the nature of the food. How are we to explain the secretion which takes place at the commencement? Is it not the same which we have already seen in the sham feeding experiments? Is not this first onrush of the stream of secretion the preliminary psychic juice? Unquestionably, gentlemen, this is the case, and we may convince ourselves of the fact in the most diverse ways. Above all, the following is clear: whatever occurs in the so-called sham feeding cannot wholly be absent in the case of normal feeding, since the former is nothing else than the isolated commencement of normal digestion. This justifiable inference is fully confirmed, if the secretion of the first hours after the administration of flesh and bread be compared with that after simple sham feeding. In the case of feeding with flesh and bread, the identically similar and high digestive power of the first hourly portions is striking, and this power coincides with what we have met in sham feeding. Further, if the quantity of juice from the miniature stomach during the first hour be compared with that produced by the non-resected part of the organ,—to do which we must multiply it by ten, since the resected cul-de-sac is approximately one-tenth of the whole organ,—it is here again found that the quantity approximately corresponds to the mean values obtained by sham feeding. Finally, the depression in digestive power or quantity of juice (with flesh, decrease of digestive power; with bread, decline in the quantity of juice), which sets in soon after the taking of food, indicates that the two conditions are connected with the ingestion of food—i. e., with a transitory factor which soon passes away and gives place to other conditions. Our explanation becomes still more convincing when we take into consideration the effects of other foods. If you give the dog, for example, something else to eat which does not interest it to the same degree as flesh or bread, you will find the initial increase in quantity and strength of juice does not appear. Offer the animal milk, for example, which in sham feeding, especially if it does not last long, calls forth, as a rule, no secretion, or at all events only very little, and the rapid flow of the commencement—the already-mentioned initial rise—absolutely fails to appear. You have already seen the figures which deal with this matter; I think it necessary, however, to bring them forward again in order that you may be better able to compare them with the secretion after flesh and bread.
The dog was given 600 c.c. of milk (experiment by Dr. Chigin).
| Hour. | Quantity of juice. c.c. | Digestive power. mm. |
| 1st | 4.2 | 3.57 |
| 2nd | 12.4 | 2.63 |
We have now begun the analytical examination of the variations of our secretory curve. But owing to the importance of the matter we did not confine ourselves to conclusions which might be drawn from earlier investigations. We turned to new forms of experiment for further proof.
Thus we divided the ordinary ration of flesh given to our dogs—400 grams—into four equal parts, which were administered at intervals of an hour and a half. (Experiments by Privat docent Kotljar and Dr. Lobassoff.) Each time after the dog received its 100 grams of flesh we were able to detect a rise both in the quantity and in the digestive power of the juice. The following table shows the figures in question: