phenomena reveal themselves in patches, in little islets on the surface of the skin, leaving sound regions at intervals. Thus, in the cases to which we allude, the perceptive regions of the sensorium-those in which the manifestations of conscious personality take place, are sometimes spared, and in a condition of complete integrity, while the neighbouring regions are invaded by different kinds of morbid processes; and then we witness a strange phenomenon-a sort of duplication of the mental unity. The individual, thus divided into two parts-one portion of himself remaining healthy, while the other is at the mercy of the phenomena of automatic, involuntary impulse-looks on, as a conscious spectator, at certain extravagant acts that he is forced to commit, at certain senseless words that he utters. He is in a manner reduced to the painful position of the tetanic patient, who at the moment of the attack sees his muscles escape from the influence of his will, contract under the influence of the cells of the spinal cord, in a paroxysm of automatic, irresistible activity, and thus become unwieldable instruments which cease to belong to him.

The annals of mental diseases include numerous examples of this state of dissociation of the vital forces of cerebral activity. There are patients sometimes who write and describe their distresses-the involuntary agonies through which they pass, the words they have pronounced unwittingly; how they are impelled to speak in spite of themselves, to say what they would not have wished to say, to go through ridiculous gesticulations, and to commit extravagances they believe themselves incapable of restraining.

A lady described by Falret uttered cries, committed all sorts of disorderly acts, and felt herself the more to be pitied, because she knew that they were acts of madness, but could not avoid committing them.* A patient described by Moreau (of Tours) presented analogous symptoms:

X-, in consequence of grief, became irritable in temper, and was seized with eccentric ideas which his reason disapproved. Suddenly the idea of tossing his bed would occur to him; but he would ask himself what was the good of it. Or he would be tempted to throw his hat upon the ground without a motive. In conversation if any one dared to contradict him, a sudden desire to beat his adversary seized him, but he restrained himself by thinking of the absurdity he would thus commit; and a crowd of delirious ideas would incessantly traverse his mind without his permitting any one to suspect him of madness, so short was the duration of his paroxysm.+

These strange phenomena, these general or partial deliriums, these strange impulses, of which we see abortive specimens in certain pregnant women, constitute, in the form of suicidal or homicidal impulses, the essential morbid elements, and in a manner the primary factors of mental pathology. They are all, in different degrees, derived from the fundamental properties of the cerebral cell, from its automatic activity past into a phase of inveterate erethism. It is always the same fundamental property which is at the bottom of all morbid

* Falret, "Annales Médico-psycholog.," 1870, p. 117. Conscious Lunatics. Unusual impulses, with disorder of intelligence. Annales Médico

psychol.," p. 84, 1857.

manifestations of the brain, and which, always present, always identical with itself, either in normal or morbid conditions of the life of the brain, becomes the source of all the disorders and all the anomalies of mental life.

P

PART III.

EVOLUTION OF THE PROCESSES OF CEREBRAL

ACTIVITY.

HAVING thus far considered the elements of cerebral activity as individual simple forces in the statical condition, we shall, in this third part of the work, consider them from a dynamic point of view, as living forces. in movement, in combination one with another, effecting reciprocal reactions, and co-operating in the different modes of mental activity.

One general fact governs the essential organization of the cerebral cortex (see p. 15). This fact is the admirable order, the regular subordination which is established in the grouping and methodical distribution of all the elements of this cortical substance. In all its regions the zones of cells are arranged one below another in thicker or thinner strata; they are strictly united one with another, both transversely and horizontally as regards this substance; the regions of small cells, moreover, everywhere occupy the superficial sub-meningeal zones, while the regions of large cells are localized in the deep regions, and communicate with the preceding by a series. of intermediate links-strata of cells which serve as