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venture to say that in the next twenty years another science equally far-reaching, equally beneficent, equally brilliant in its achievements, may not arise? Even the present is a splendid time,

"An age on ages telling
To be living is sublime."

But the twentieth century in which you will live will be the most glorious time of all the ages. But you may take part in this grand march of progress, not only in the rank and file, but as a leader if you will but study and write. Or it may be, if you have the gift of imparting knowledge, you may be one of the teachers of medical science, an enviable post of honor and responsibility, but also of unequalled enjoyment.

Have I not put before you enough to arouse the ambition, the energy, the benevolence, the enthusiasm, of any young man about to choose his career? Can there be in any other department of human knowledge so fine a field for research, for discovery, for fame, and, what is far better, for serving the human race? If, in consequence of what I have said to you, some of you will select Medicine as your chosen pursuit, rest assured that if you will faithfully perform your duty, at the close of life you will have the pleasure of surveying a career which has been advantageous to yourselves, has been a means of doing good to your fellow-men, and I verily believe has approximated as near as possible to the Divine Life as is given to any man to do.



"Harper's Magazine" for October, 1889, I contributed

extent the causes, of the recent marvellous progress of surgery. In this, as in an earlier publication, I attributed it to a large extent to vivisection. Both publicly and privately my statements have been called in question.

The seven years which have elapsed since my first publication on this subject have demonstrated, far more than I even hoped or expected, the truth of what I then stated, and it would seem right that some of these demonstrated facts should be laid before the public. Moreover, the recent revival of the discussion of the subject before the Church Congress at Folkestone, England,† and at the recent meeting of the Humane Society in Philadelphia in October, 1892, makes it especially timely.

I shall omit many topics which would be suitable, such as the wonderful results of Pasteur's treatment of hydrophobia, the discoveries of bacteriology, the wholly new class of remedies which medicine owes to vivisection, such as the antidotes to lockjaw and several other diseases, derived from the blood of animals inoculated with the virus of these diseases-remedies to which we already owe astonishing cures. In the present paper I propose to limit myself to brain surgery alone, and to give a glimpse of what has been done up to the present time. I shall show especially that

* Reprinted from Harper's Magazine for June, 1893, by the kind permission of Messrs. Harper & Brothers.

† Church Times, October 14, 1892, p. 1021.

without the exact knowledge of the functions of the brain, derived almost wholly from experimentation upon animals, it would be simply impossible to do what has been accomplished. I shall not restrict myself to general assertions which may easily be denied, but I shall relate actual cases, with their definite results, and the authority for each case.

In order to understand modern progress in cerebral surgery it is necessary first to understand what has been achieved by experimentation upon the brain. When I was a student of medicine, thirty years ago, the brain was regarded as a single organ, and its various functions were not thought to have any especial localized centres of action.* When the brain acted it was thought that the whole of it acted, just as the liver or the stomach acts, as a whole. Now we know that, instead of the brain being a unit, it is really a very complex organ. Just as in the abdomen, besides the other organs in its interior, we have the stomach, the liver, the pancreas, and the bowel, each of which has its part in digestion, so correspondingly in the brain, besides the portions concerned in sight, smell, thought, etc., we have four adjacent portions which are concerned in motion. One produces motion of the face; another motion of the arm; a third, motion of the leg; and the fourth, motion of the trunk.

How, it may be asked, have these facts been determined? Has it not been by observing the effects of injuries and diseases in man? To a small extent, yes. But very, very rarely does disease or injury involve only one of these very limited regions of the brain; and the moment two or more of them are involved our inferences become confused and misleading. As a matter of fact which cannot be gainsaid, nine-tenths of our knowledge has been derived from exact experiment upon animals, and in this way: A monkey is

*The "bumps" or localized centres of phrenology were always discredited by the medical profession, and experiments upon animals and observation in man have entirely overthrown them.

etherized, a certain area of its brain is exposed, and an electrical current is applied. This stimulation of most portions of the brain is followed by no motion in any part of the body. These parts of the brain, therefore, have nothing to do with motion, but are the centres for general sensation (touch) or for certain special senses, as sight, hearing, etc., or for mental processes. But in one definite region of the brain, called the "motor area," the moment the brain is stimulated by the electrical current motion is produced. Moreover, it was soon found that stimulating different parts of this motor area produced motion in different parts of the body, and that this was not haphazard, but that stimulation of one part of it always produced motion in the arm, and in another part motion in the leg, etc. Thus have been mapped out the various portions of the motor area, as will be presently described in detail.

It is evident that by experiment upon animals the motor area can be more easily and more exactly determined than can those regions which are the seat of the faculties of smell, taste, sight, and hearing, the presence or absence of these senses in animals being difficult to determine with absolute accuracy. Still more is this true of the parts of the brain which have to do with mental processes. Yet disease and injury in man, if they alone could answer the questions what part of the brain has to do with motion, what part with sight, what part with the intellect, ought to have answered them long ago. No better evidence could be given of the superiority of experiment upon animals over observation of accident and disease in man in determining facts of this character than this, that those centres are best and most accurately known which can be determined by vivisection, and that those in which vivisection can aid us but little are still only vaguely located. Thus the motor area is positively and definitely located; that for sight approximately well; those for hearing, smell, and taste and general sensation

(touch) are still uncertain, though guessed at. As to those for mental processes, except perhaps one which will be alluded to later, we are almost wholly in the dark. Moreover, disease and accident have made their cruel and rude experiments ever since the world began. But as a matter of fact the last fifteen years of experimentation have taught us more than the previous fifteen hundred years of careful observation and of postmortem examination.

Let me now briefly explain this "localization of function" in the brain, and then show its value and certitude by cases

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Fig. 1.-Side view of the surface of a monkey's brain, showing the location of the various fissures and of the motor centres. (Horsley and Schäfer.)

which arouse our interest not only by their illustrating the practical applications of science, but by the cheering and humane results in the relief of human suffering and the saving of human life.

Fig. 1 represents the motor area as ascertained by many experiments such as I have described upon the brains of monkeys. On its surface will be observed certain broad black lines labelled, from in front backward, "Precentral sulcus, Fissure of Rolando, Intraparietal fissure, External parieto-occipital fissure, Fissure of Sylvius, Parallel fissure,” and others without names. In the middle, running down

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