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ad the patient lived。 This is undoubtedly the reason why a severe case of exophthalmic goiter sustains a permanent loss of brain power。
Insomnia。The brains of rabbits which had been kept awake for one hundred hours showed precisely the same changes as those shown in physical fatigue； strychnin poisoning； and exhaustion from emotional stimulation。 Eight hours of continuous sleep restored all the cells except those that had been completely exhausted。 This will explain the permanent ill effect of long…continued insomnia； that is； long…continued insomnia permanently destroys a part of the brain…cells just as do too great physical exertion； certain drugs； emotional strain； exophthalmic goiter； and hemorrhage。 We found； however； that if； instead of natural sleep； the rabbits were placed for the same number of hours under nitrous oxid anesthesia； not only did the brain…cells recover from the physical deterioration； but that 90 per cent。 of them became hyperchromatic。 This gives us a possible clue to the actual chemical effect of sleep。 For since nitrous oxid owes its anesthetic effect to its influence upon oxidation； we may infer that sleep also retards the oxidation of the cell contents。 If this be true； then it is probable that inhalation anesthetics exert their peculiar influence upon that portion of the brain through which sleep itself is produced。 If nitrous oxid anesthesia and sleep are chemically identical； then we have a further clue to one of the primary mechanisms of life itself； and as a practical corollary one might be able to produce artificial sleep which would closely resemble normal sleep； but which would have this advantage； that by using an anesthetic which interferes with oxidation the brain…cells might be reconstructed after physical fatigue； after emotional strain； or after the depression of disease。
In the case of the rabbit in which nitrous oxid was substituted for sleep； the appearance of the brain…cells resembled that in but one other group experimentally examinedthe brain…cells of hibernating woodchucks。
Insanity。Our researches have shown that in the course of a fatal disease and in fatal exhaustion； however produced； death does not ensue until there is marked disorganization of the brain tissue。 In the progress of disease or exhaustion one may see in different patients every outward manifestation of mental deterioration； manifestations which； in a person who does not show any other sign of physical disease； mark him as insane。 Take； for example； the progressive mental state of a brilliant scholar suffering from typhoid fever。 On the first day of the gradual onset of the disease he would notice that his mental power was below its maximum efficiency； on the second he would notice a further deterioration； and so the mental effect of his disease would progress until he would find it impossible to express a thought or to make a deduction。 No one can be philanthropic with jaundice； no one suffering from Graves' disease can be generous； no mental process is possible in the course of the acute infectious diseases。 Just prior to death from any cause every one is in a mental state which； if it could be continued； would cause that individual to be judged insane。 If the delirium that occurs in the course of certain diseases should be continued； the patient would be judged insane。 In severe cases of Graves' disease the patient is insane。 Individuals under overwhelming emotion may be temporarily insane。 Every clinician has seen great numbers of cases in which insanity is a phase of a disease； of an injury； or of an emotion。 The stage of excitation in anesthesia is insanity。 The only difference between what is conventionally called insanity and the fleeting insanity of the sick and the injured is that of time。 We may conclude； therefore； what must be the brain…picture of the person who is permanently insane。 This _a priori_ reasoning is all that is possible； since the study of the brain in the insane has thus far been confined to the brains of those who have died of some disease。 And it is impossible to say which changes have been produced by the fatal disease； and which by the condition which produced the insanity。 The only logical way by which to investigate the physical basis of insanity would be to make use of the very rare opportunities of studying the brains of insane persons who have died in accidents。
Our experiments have proved conclusively that whether we call a person fatigued or diseased； the brain…cells undergo physical deterioration； accompanied by loss of mental power （Figs。 40 to 43）。 Even to the minutest detail we can show a direct relationship between the physical state of the brain…cells and the mental power of the individual； that is； the physical power of a person goes _pari passu_ with his mental power。 Indeed； it is impossible to conceive how any mental action； however subtle； can occur without a corresponding change in the brain…cells。 It is possible now to measure only the evidences of the effects on the brain…cells of gross and violent mental activity。 At some future time it will doubtless be possible so to refine the technic of brain…cell examinations that more subtle changes may be measured。 Nevertheless； with the means at our disposal we have shown already that in all the conditions which we have studied the cells of the cortex show the greatest changes； and that loss of the higher mental functions invariably accompanies the cell deterioration。
A MECHANISTIC VIEW OF PSYCHOLOGY＇*＇
＇*＇ Address delivered before Sigma Xi； Case School of Science； Cleveland； Ohio； May 27； 1913； and published in _Science_； August 29； 1913。
Traditional religion； traditional medicine； and traditional psychology have insisted upon the existence in man of a triune nature。 Three 〃ologies〃 have been developed for the study of each nature as a separate entitybody； soul； and spiritphysiology； psychology； theology； physician； psychologist； priest。 To the great minds of each class； from the days of Aristotle and Hippocrates on； there have come glimmerings of the truth that the phenomena studied under these divisions were interrelated。 Always； however； the conflict between votaries of these sciences has been sharp； and the boundary lines between them have been constantly changing。 Since the great discoveries of Darwin； the zoologist； biologist； and physiologist have joined hands； but still the soul…body…spirit chaos has remained。 The physician has endeavored to fight the gross maladies which have been the result of disordered conduct； the psychologist has reasoned and experimented to find the laws governing conduct； and the priest has endeavored by appeals to an unknown god to reform conduct。
The great impulse to a deeper and keener study of man's relation； not only to man； but to the whole animal creation； which was given by Darwin； has opened the way to the study of man on a different basis。 Psychologists； physicians； and priests are now joining hands as never before in the great world…wide movement for the betterment of man。 The new science of sociology is combining the functions of all three； for priest； physician； and psychologist have come to see that man is in large measure the pr