Fear Page #16

THE learned and eloquent Professor of Physiology at Turin has given us in the book which he has entitled “Fear,” an analysis of this mental condition and its accompanying physical states, which, marked as it is by scientific accuracy and couched in charming and even in poetical diction, will take high rank as a popular exposition of our knowledge of the expression of one of the most interesting of the emotions of both men and animals.

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[Illustration: FIG. 1.--PULSE OF THE HUMAN BRAIN DURING SLEEP]

After an hour and a half, when I saw that Bertino was breathing quite calmly, with the rhythm and in the characteristic manner of a sleeper, I rose with great caution, approached the pillow on which he had laid his head, and at that point in the curve where is the sign of the arrow, ↓, I called him gently by name, 'Bertino.’ He did not move or answer. If we examine the curve in fig. 1, we find that even before the sign, ↓, four pulsations are somewhat higher than the preceding ones. This first increase in the volume of the brain is due to the very slight noise which I involuntarily made with the chair on rising to approach Bertino.

After calling him by name, the brain wrote three pulsations which have the form of the preceding ones; then the pulse changed, and the pen traced four pulsations, one higher than the other. This is the beginning of what I have called an undulation. During the next pulsations the pulse-line gradually falls until it reaches the previous height. In comparing the form of the pulsations at the beginning of this curve with those at the end, we see that even this very slight emotion, which was not able to interrupt sleep, yet sufficed to produce a great modification. The pulse is stronger, its form tricuspid. We physiologists would say that, from being anacrotic, it had become catacrotic. But the variations which appear in the circulation of the brain during fear are far greater. The reproofs and threats which I uttered to Bertino when he was hindering my experiments by moving his head or hands, the disagreeable things which I sometimes purposely said to him, were always followed by very strong pulsations; the brain-pulse became six, seven times higher than before, the blood-vessels dilated, the brain swelled and palpitated with such violence that physiologists were astonished when they saw the reproductions of the curves, published in the tables of my researches on the circulation of the brain.[13]

[13] R. Accademia dei Lincei, vol. v. series 3a; Nuova Antologia, March 1881.

VII

In Canada, in 1822, a soldier called Alexis St. Martin was shot at from a short distance. The bullet penetrated the abdomen, perforating the stomach. In a few months, thanks to the treatment of Dr. Beaumont, he was completely healed, only an opening remained in the abdominal walls through which the processes in the stomach could be seen. Several physiologists in America had thus the opportunity of observing the stomach during digestion by looking into its cavity as through a window. The investigations made on this soldier resulted in the statement that the stomach becomes redder as soon as digestion begins. Later, physiologists showed, by other observations, that the salivary glands grow red during mastication, and that the muscles contain more blood when they are at work a long time. We all know that the eyes of anyone who works long become red, that the feet swell after a long walk, and that, in fencing, the muscles of the arms and the hand which grasp the weapon grow thicker.

From these facts we may deduce a law which has no exceptions, namely, that blood is more copiously supplied to an active organ.

The organs of our body are like so many little machines, to which one must furnish fuel if their working power is to be increased. But whereas, in ordinary mechanisms, it is a strange hand which keeps up the fire and directs the movements, our organism is so perfect that in it all apparatus regulate themselves with the greatest harmony of object. In the working muscle the blood-vessels expand, thus more easily to transmit the fuel, and in order that the muscle may convert the chemical force of food into a contraction. In the digesting stomach the circulation is more abundant, because the glands must secrete a greater quantity of juice, the little veins absorb the fluids contained in the stomach, and the muscles contract more quickly in order to mix the food.

Our organism, like all working machines, not only consumes and destroys fuel, here represented by those elements which constitute the blood, but through its activity it also wastes those parts of the body which represent the wheels, axles, hinges, and other parts of a mechanism. At every contraction of the muscles, at every sensation in the brain and nerves during any mental work, there is a wasting of the organs. The blood, flowing continually through all parts of the body in order to feed the flame of life, sweeps at the same time the most remote corners of our organism clean of soot, or the remains of combustion. The vessels become relaxed and expand. Nutrition and organic change become more rapid, the nutritive fluid trickles more easily through the walls of the vessels, the blood flows more quickly, and carries everywhere along with it all the waste products in order to bring them to the kidneys. These purify the blood, and expel, with the urine, the scoriæ of the working organism.

We have seen how the circulation in the brain is accelerated during mental activity, emotion, and in a waking condition; we shall return to this subject in the next chapter, and study more nearly the mechanism by which such variations are produced in all the other organs of the body. This subject is of great importance to physiologists, because in no other way can the slender link which connects psychological phenomena with the material functions of the organism be rendered more evident.
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