490 THE POPULAR SCIENCE MONTHLY. 



of the left, and never with disease of the right side of the brain. To 

 the brief explanation of this curious fact we shall presently return ; but 

 we may in conclusion remark certain facts now known respecting the 

 locaHzation of other functions. Professor Ferrier, of King's College, 

 London, employing electricity as the only agent and means of stimula- 

 tion to which the non-sensitive brain will respond, has succeeded in 

 mapping out in the brains of higher animals the centers which govern 

 many of the common movements of life, and which from reasonable 

 analogy may be presumed to be represented in the human brain as well. 

 As these acts are the practical outcome of ideas, the parts of the brain 

 concerned in the production of definite ideas may thus be regarded as 

 being in one sense mapped out and recognized ; although it is hardly 

 necessary to remark that the regions of Dr. Ferrier in no wise correspond 

 to those of the old phrenolog}', while in many cases, indeed, they are 

 utterly opposed to it. Thus the sense of touch is found to be localized 

 in the inner surface of the hemispheres of the brain, and this fact alone 

 tells against the phrenologist, to whom the mere brain-surface is the 

 brain itself. 



Thus the work of localizing movements and important centers of 

 the senses has so far proceeded with success. There yet remains for 

 observation the curious case of aphasia or speechlessness, and its loca- 

 tion in a " speech-center " or " speech-organ " in the front of the left 

 hemisphere of the brain. It is a noteworthy fact in brain-physiology, 

 that when an animal has been rendered blind by the destruction of the 

 sight-center of one side, blindness disappears and sight gradually re- 

 turns, since the remaining and normal sight-center of the opposite side 

 assumes the functions of its neighbor. Complete blindness only ensues 

 when both sight-centers are diseased. The same remark holds good of 

 the movements of the mouth and tongue in speech, these being " bi- 

 lateral," so that the center of these latter movements on one side may 

 be destroyed without causing paralysis of the tongue, provided the cen- 

 ter of the other side is uninjured. Movements of the hands and feet 

 are, on the contrary, one-sided. Destruction of one center governing 

 these latter movements insures complete cessation of the movements 

 on the opposite side of the body. Now, in aphasia or speechlessness, 

 we merely perceive the results of the destruction of the single speech- 

 center — the left — which man normally possesses. Just as we use the 

 right hand in preference to the left in prehension and in writing, and as 

 the movements of this hand are regulated by the left side of the brain, 

 so our faculty of articulation is also unilateral and single-handed, so to 

 speak. The memory of sounds and words forms the basis of our speech 

 — "the memory of words is only the memory of certain articulations" 

 — and those parts of the brain which regulate articulation are also the 

 memory-centers for speech or the result of articulation. Thus, when 

 the speech-center is disorganized, not merely the power of articulation 

 disappears, but also the memory of words. But while the left side is 



