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 

 diao-ram to which I direct your attention shows the arrangement on a 

 greatly magnified scale. More than nine years ago, in an address de- 

 livered 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 — per- 

 ception, 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 voli- 

 tional 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 in- 

 tellect, emotion, and will — would be, in fact, lower in mental develop- 

 ment 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 differen- 

 tiate 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 scintilla- 

 tion. 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 function- 

 ates, 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 trans- 

 mitted ; if the ganglion is disordered, the perceptive force is not 

 evolved. Therefore, in order that a true perception may be experi- 

 enced, 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 



