THE STUDY OF NEUROLOGY 233 



dition of the patient than the seemingly less serious psychic 

 seizures. 



We owe also to Hughlings Jackson the generalization that lesions 

 which occur suddenly, and throw out of gear, as they are bound 

 to do, the more delicate of the functions represented in that part 

 of the nervous system which is concerned, are likely to be followed 

 by symptoms of a more violent sort than those which take place 

 slowly. Thus, the epileptic discharge accompanying a lesion so 

 slight as to leave no recognizable anatomic trace behind is liable, 

 by virtue of its suddenness, to give rise to a maniacal outbreak, 

 which represents the uncontrolled activity of relatively uninjured 

 portions of the brain, while, on the other hand, lesion which anatom- 

 ically may appear infinitely more serious are accompanied by no 

 such outburst. Different forms of epileptic discharge and their sec- 

 ondary results differ widely also among themselves in these respects. 



These hypotheses are in need of further analysis and should be 

 tested anew by neurologists trained in physiological methods. 



Reasoning on lines similar to those laid down by Hughlings Jack- 

 son, Edward Cowles has recently sought to unify the various mem- 

 bers of the large class of the psychoneuroses of exhaustion, or of 

 lowered mental tension. Thus the different phases of manic-de- 

 pressive insanity are not due, he thinks, to separate and specific 

 processes for which we might expect to find special chemic or ana- 

 tomic expressions, one process leading to excitement and another 

 to depression, but these phases, which in fact are often mixed, are 

 phenomena of secondary occurrence, and are explicable on prin- 

 ciples analogous to those outlined above as indicating the genesis 

 of epileptic mania. 



Some of the principles brought out by Hughlings Jackson are 

 quite in harmony with those insisted upon of late years by a re- 

 latively small group of observers, abroad and at home, who have 

 brought psychologic investigations to the aid of clinical research. 

 I have especially in mind the fine work done by such men as Janet 

 and Treud in Europe, Morton Prince and Sidis in America, not to 

 speak of many others who have labored in the same field. To them 

 we owe such knowledge as we now possess of the contrast between 

 the dissociation of consciousness so characteristic of hysteria, and 

 of the contrast between this tendency and that which gives rise to 

 the complex and varied mental phenomena of asthenic states, or 

 to the temporary and quasi-normal disturbances of daily life. 



It would be impossible even to name, in a few paragraphs, the 

 many clinical researches tending toward a better understanding 

 of mental symptoms, for the prosecution of which a knowledge of 

 psychological and physiological generalizations is essential. A few 

 illustrations must suffice. 



