The gastric laboratory uses its protein ferment under an acid reaction.
While you are experimenting, do not remain content with the surface of things.
Don't become a mere recorder of facts, but try to penetrate the mystery of their origin.
Appetite, craving for food, is a constant and powerful stimulator of the gastric glands.
But man has still another powerful resource: natural science with its strictly objective methods.
Physiology has, at last, gained control over the nerves which stimulate the gastric glands and the pancreas.
Only by observing this condition would the results of our work be regarded as fully conclusive and as having elucidated the normal course of the phenomena.
From the described experiment it is clear that the mere act of eating, the food even not reaching the stomach, determines the stimulation of the gastric glands.
Perfect as the wing of a bird may be, it will never enable the bird to fly if unsupported by the air. Facts are the air of science. Without them a man of science can never rise.
It is not accidental that all phenomena of human life are dominated by the search for daily bread - the oldest link connecting all living things, man included, with the surrounding nature.