peculiar metabolic action of the nervous plexuses in the womb of which it is incarnated, and then, transforming itself into a psychic excitation, it develops the latent energies proper to the cerebral cells, imprints itself upon them, and perpetuates itself in them in the form of persistent vibrations, like a phosphoric gleam of the external world.

Thus it is, that this mysterious property which the nervous elements possess-that of persisting in the vibratory condition in which they have been placedis here again found consistent with itself throughout the different stages traversed by the sensorial excitations; from the peripheral regions where it reveals itself in so indubitable a manner (as in the persistence of impressions on the retina), to the central regions, where it acquires characters entirely dependent upon the multitude of elements which serve to maintain it.

Thus it is then, that external impressions of all kinds, the diverse emotions we have felt, become finally attenuated in the plexuses of the sensorium, and in the form of persistent vibratory thrills become the posthumous expressions of impressions and past emotions which remain alive in us when the primordial excitations have long ago disappeared.

Sensorial excitations, when they are diffused in the plexuses of the sensorium and fix themselves there. in a persistent manner, do not usually remain there in the state of vague, uncertain impressions. They go further, penetrate more deeply into the recesses of cerebral life, and when they are sufficiently lively and often enough repeated, they penetrate even into those inmost regions where the notion of conscious personality

is elaborated, and thus become conscious reminiscences of ancient emotions that have thrilled us.

Thus it is that, as regards the phenomena of memory, our inner personality is seized upon by the same process by which it was seized upon on the arrival of sensorial impressions; only that these impressions which call it into activity prolong their action, implant themselves in the organism, and become, as it were, a vibratory echo of the past. It is thus then, that the reminiscence of anterior excitations perpetuates itself in the sensorium with the particular coefficients of joy or sorrow that have presided over their genesis in the peripheral regions, and thus a series of emotions related to each of them becomes developed, and perpetuates itself in the central sensitive regions of our organism.

The phenomena of psychical and moral activity, understood as we have previously explained, perpetuate themselves in a similar manner, and develop incessantly, by the mere calling into activity of the two fundamental processes of the nerve-cells-sensibility, and that peculiar retentive power, organic phosphorescence, by means of which they prolong the vibratory excitations which have first set them in motion.

In the domain of intellectual activity it is still the same force that underlies most of the dynamic operations to which this activity gives birth.

It is, indeed, because he remembers, because his sensibility has been impressed in a special manner, and this impression is persistent in him, that the young child, from the first instant of his life, expresses his inner sentiments. It is because he remembers, that he recognizes external objects and names them with an

appropriate word, which he has retained in his memory from having heard it. It is by means of the persistence of acoustic impressions, preserved in the state of sonorous reminiscences, that he speaks, and that his phonetic expressions are applied to each surrounding object.

It is also by the same means that he learns to trace written characters, which he recognizes as the symbolic expression of absent objects, and that he reads aloud, transforming each written character into sonorous concordant expressions which he knows to be their equivalents.

There are always at the bottom of these different operations of the intelligence, persistent sensorial impressions which direct the processes in evolution, and vibrate like a faithful echo of the first impression. It is the same with that admirable faculty which the human being possesses, the power of translating into verbal expression his emotions and the thoughts which pass through his mind. It is because man has learned that each word expresses an external object, a thought, a sentiment, and because this acquired notion, preserved by daily use, is maintained in him in a state of permanent freshness, that he speaks, addresses his kind, and is understood by them. It is memory-the accumulated reminiscences always present to the mind-that forms the basis of his language, and thus becomes the inexhaustible store in which he finds the means of expressing what he feels and what he thinks.

CHAPTER III.

THE MEMORY IN EXERCISE.

BESIDES those phenomena of memory into which the human personality more or less enters, there exist a whole series of similar acts which represent processes of memory to some extent incompletely developed.

These are those phenomena in which sensorial excitations, not having carried their action as far as the plexuses of conscious personality, remain in the condition of sterile materials, not perceived by the sensorium. Like those dark ultra-violet rays of the spectrum, which though not perceptible to our eyes, have nevertheless a real existence, they remain silently accumulated in the plexuses of the cerebral cortex, and only await the presence of an exciting cause capable of causing them to start from their obscurity.

Thus, we all know that during the period of our diurnal activity, there are a host of various impressions which assail us on all sides, and even strike redoubled blows upon our sensitive plexuses, yet to which we pay no attention. The multifarious noises of carriages rolling around us all day, finally come to be unperceived by us and indifferent to us. We know also that when we give ourselves up to an absorbing intellectual work, the ticking of the clock beside us strikes

in vain upon our ears, and yet our acoustic nerves have been again and again set vibrating without our having a notion of it.

Onimus has made a very curious observation in connection with this class of ideas. A man who was walking began automatically humming an air, being very much surprised by its having come into his head. It was only accidentally that he perceived that the air had been suggested to him by a wandering musician who was playing it on his instrument as he passed by, and whom he had not perceived.* This man in humming the air echoed an auditory impression, an unconscious reminiscence.

We all know that in examining a picture, or landscape, or a histological preparation, we first passively see the whole, and that certain details when we are not prepared for them at first escape us; and if a person, after we have gone to a distance from the object we have examined, retrospectively calls to our notice certain peculiarities of the object, we are quite astonished that we have remarked them, and that we recognize in ourselves the existence of certain impressions which have remained silent.

It is by means of unconscious impressions which persist in the brain that the activity of our spirit, in the automatic work which takes place in the act of reflection and meditation, is maintained.

It is thus that the unexplored sides of certain questions in suspense are made clear by the juxta-position of old impressions which have arisen. A sort of automatic appeal is made to revived impressions which have

* Onimus, "Journal d'Anat. et Physiol.," de Robin, p. 551, 1873.