Page:Popular Science Monthly Volume 11.djvu/346

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Genius is a natural force which possesses a value only in so far as work has been expended in developing and applying it; this work produces values by consuming values.

All mental labor is at the same time brain-labor. The brain consumes a certain amount of food-material. Of course, all the other involuntary bodily movements which go on simultaneously with the brain-movements, as also the necessary periods of rest, must be taken into account in estimating the value of the products of mental labor.

Here, too, a definite amount of food-substances gives a definite quantity of (mental) work.—Das Ausland.



THE facts which I propose to consider in this paper have been brought to light by means of the experimental method. They are very interesting, both physiologically and psychologically viewed. I shall occupy myself with the physiological aspects only, and their bearing on human pathology. Psychology is beyond my province. Moreover, I conform myself to the saying of Montaigne, that deductions are very difficult to draw in psychological science, for "comment cognoit on la semblance de ce de quoi on ne cognoit point l'essence?"[1]

Most of the facts observed, of hereditary transmission of nervous disorders, were put on record many years ago by my eminent friend and teacher Dr. Brown-Séquard. Some I have observed, together with him, during the years that I was his assistant, and others I have discovered quite lately.

The disorders which were inherited had all been artificially induced in animals for the sake of experimentation. Very great care was taken in all cases to avoid causes of error, and I am positive that they were got rid of completely.

It will be seen that lesions which affect not only nutrition of parts, but also the higher functions of the nervous system, can be developed by hereditary tendencies, when artificially provoked, through those nerves which minister to organic functions—belonging to the so-called sympathetic system.

It is well known that a system of nerves exists in all animals which have a circulation, and which apparently has no other functions but to control the blood-vessels, to regulate the flow of the blood through them. This nervous system is called, therefore, the vaso-motor system; it is also termed the sympathetic.

  1. How can one know the like of that of which one knows not the essence?