When the currents of blood which carry life to the cells of the sensorium are suspended, another order of very significant phenomena is developed. There is a sudden arrest of the working of the living machine. Everything stops at once ; everything imme diately remains suspended. The perceptive regions of the sensor/um, struck, in a manner, with asphyxia, are all at once deprived of the property of feeling excita tions from the surrounding medium ; they remain torpid, inert, and the human personality ceases at the same time to be conscious of the things of the external world, of which it thus loses the knowledge (syncope, fainting, epileptic vertigo).
Again, if the plexuses of cells in the cortical sub stance, which are to a certain extent isolated as regards the arrival of blood in their tissue, as they are as regards dynamic activity, receive at a given moment more blood than is their wont, and thus assume a condition of morbid erethism, the regions ef.con scious personality remaining comparatively unaffected, a strange phenomenon will result, in which the individual, without having lost consciousness of external things, will be almost passively hurried away by the auto matic activity of certain regions of his brain, which will urge him to utter words and to commit extravagant actions, and this in an irresistible manner, and quite without the agency of his will.
These facts lead us to the opinion that the pheno mena of conscious perception, like true physiological processes, are decomposable by analysis into successive phases, and that they only develop and come to per fcction through the integrity of the different media which give them birth.
From this point of view they are quite comparable to the phenomena of bxmatosis, which take place in an incessant and continuous manner only by means of the effective co-operation of a series of apparatuses of organic life, for this common end. I-kematosis is, in its essence, a fundamental operation as important in the sphere of the phenomena of organic life as conscious perception in that of the phenomena of psychical activity. In the first case it is the arrival of the oxygen that comes to animate the blood-corpuscle and render the venous blood ruddy at the moment of its passage into the pulmonary tissue. In the second case it is the incessant and uninterrupted arrival of stimulations from the external world which animates the cerebral cell and excites its latent energies. In both cases it is the non-interruption of the arrival of the external element which is the cause of the perpetual maintenance of the function which occurs as its con sequence ; so much so that the notion of conscious personality is, in its essence, a phenomenon of vital order which exists only through the continuity and co operation of the nervous apparatuses laid under contri bution.