Page:Popular Science Monthly Volume 26.djvu/18

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8
THE POPULAR SCIENCE MONTHLY.

end of the trunk, and is at its thickest portion about the diameter of the end of the little finger. It contains throughout its whole length gray nerve-tissue arranged somewhat in the form of the letter H. The diagram to which I direct your attention shows the arrangement on a greatly magnified scale. More than nine years ago, in an address delivered before the New York Neurological Society, and entitled "The Brain not the Sole Organ of the Mind," I called attention to the fact that certain mental faculties are seated in the spinal cord. It will probably not be out of place if I adduce here some of the facts and arguments upon which I based that opinion, and which convince me of its correctness.

As we have just seen, all the manifestations of which the mind is capable in its fullest development are embraced in four groups—perception, the intellect, the emotions, and the will. Either one of these may be exercised independently of the others. Thus, an individual may have a perception without any intellectual, emotional, or volitional manifestation, and so the intellect, the emotions, or the will may be brought into action without the necessary participation of each other. It is, however, clearly established that all mental processes of any kind have their origin in perception, and that an individual born without the ability to perceive, either from defects in the external organs of the senses, or of the central ganglia by which impressions on these organs are converted into perceptions, would be devoid of intellect, emotion, and will—would be, in fact, lower in mental development than the most degraded types of animated beings. He would not, in fact, be able to conceive of so simple an idea as that one and one make two. How could he, unless he could see two objects, or hear two sounds, or smell two odors, or taste two flavors, or feel two tactile impressions? There would be no means by which he could differentiate one from two, for no knowledge on the subject could reach his brain. Though he might have the intellectual potentiality of Socrates, he would be an actual imbecile, without the slightest mental scintillation. The brain and other nerve-centers can only act from impressions received from without.

Perception is, therefore, the primary manifestation of mind, and is that part the office of which is to place the individual in relation with external objects. Thus an image is formed upon the retina, the optic nerve transmits the excitation to its ganglion, this at once functionates, the force called perception is evolved, and the image is perceived. If the retina be sufficiently diseased, the image is not formed; if the optic nerve is in an abnormal condition, the excitation is not transmitted; if the ganglion is disordered, the perceptive force is not evolved. Therefore, in order that a true perception may be experienced, an organ of sense, a nerve, and a mass of gray nerve-tissue are necessary, and no other organs are required.

It is rarely the case that an individual perceives an impression