Page:Popular Science Monthly Volume 78.djvu/61

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repeated step for step in the life history of each individual. From the first movements of the embryo until the adult has reached the prime of development, the line of progressive functional development is unbroken. In the earlier studies made upon the brain local lesions such as those caused by apoplexy, injury, tumors, etc., were the first to attract and interest the public as well as physicians. It was much more difficult to understand the diseases of the brain not dependent upon localizable lesions, but gradually a way was found leading to a better understanding and clearer analysis of the mental disturbances occurring without discoverable lesions. But the brain is so complicated an organ that a slight interference with its mechanism may give rise to complicated functional disorders involving the entire personality. As a matter of fact comparatively little is yet known in regard to the cumulative effect of disturbances in the mental activity incident to relatively small lesions in the higher brain centers. In the study of the various psychoses the alienist has found a complete analogy to the results obtained in the study of the comparative physiology of the brain. When the attempt was made to analyze the anomalies of conduct in the insane it became evident that no distinctive qualitative difference separated them in behavior from normal individuals. In the daily ups and downs of the ordinary life are found the basis of the pathological conditions known as manic-depressive insanity, while in the precocious bizarre habits of young people and children are recognized the germs of that sad group of cases known as dementia præcox. In the rigid inflexible opinions so frequently expressed in the discussion of religious or political questions we find the key explaining the stand-pat positions of individuals subject to chronic systematized insane ideas.

The individuals showing a particular bias, or those inoculated with the spirit of excessive partisanship, the sentimentalists, the whole host of faddists, the doctrinaires, the obstinate and the bigots to a certain extent reflect but to a less degree some of the mental traits of the paranoiac. The permanence and intensity given to certain ideas have been the result of the emotional storms attending their appearance in consciousness, and in the latter condition, where a marked psychosis has intervened, the intense emotional reaction has subsided and the idea has crystallized out of its setting. In the normal individual when one function of the brain is nicely balanced against the other the analysis of behavior is, as a rule, more difficult than it is in the insane in whom the exaggeration of different traits of character becomes so marked that a clue as to their origin and development is given.

In the history of psychology it is particularly interesting to note that practically every advance made in this department has followed close upon the incorporation of the conceptions and terms of natural science; and it is equally obvious that the delays and regressions have