for a vague phrase upon the conservation and reproduction of memory, a clear representation of the extremely complex process which produces and sustains it. The first point to be established is with regard to the seat of memory. This question can give no room for serious controversy. The law, as formulated by Bain, is that "the renewed feeling occupies the very same parts, and in the same manner, as the original feeling." To give a striking example: experiment shows that the persistent idea of a brilliant color fatigues the optic nerve. We know that the perception of a colored object is often followed by a consecutive sensation which shows us the object with the same outline, but in a complementary color. It may be the same in the memory. It leaves, although with less intensity, a consecutive image. If with closed eyes we keep before the imagination a bright-colored figure for a long time, and then suddenly open the eyes upon a white surface, we may see for an instant the imaginary object with a complementary color. This fact, noted by Wundt, from whom we borrow it, proves that the nervous process is the same in both cases-in perception and in remembrance." We now begin to see more clearly into the * For further details on this point, see Bain, "The Senses and the Intellect," p. 358. problem of the physiological conditions of memory. These conditions are: 1. A particular modification impressed upon the nervous elements. 2. An association, a specific connection established between a given number of elements. This second condition has not received the attention which it merits, as we shall endeavor to show. To keep for the present to the organic memory, let us take one of the secondary automatic movements which have served as a type, and consider what takes place during the period of organization; let us take, for example, the movements of the lower limbs in locomotion. Each movement requires the operation of a certain number of muscles, tendons, joints, ligaments, etc. These modifications-for the most part, at least-are transmitted to the sensorium. Whatever opinion may be held with regard to the anatomical conditions of muscular sensibility, it is certain that the sensibility exists, and that it makes known the part of the body participating in a movement, and permits us to regulate it. What does this fact show? It implies modifications received and conserved by a determined group of nervous elements. "The movements that are instigated or actuated by a particular nervous center do, like the idea, leave behind them residua, which, after several repetitions, become so completely organized into the nature of the nervous center that the movements may henceforth be automatic."* "The residua of volitions, like the residua of sensations or ideas, remain in the mind and render future volitions of a like kind more easy and more definite.”† By this organization of residua, after the period of experiment of which we have spoken, we are able to execute movements with facility and increasing precision, until they finally become automatic. Submitting this familiar instance of organic memory to analysis, we see that it implies the two conditions mentioned above. The first is a particular modification impressed upon the nervous elements. As this has been often discussed, it need not detain us. But does the nervous fiber, in receiving an entirely new impression, retain a permanent modification? This point is disputed. Some regard the nerves as simple conductors, whose constituent matter, disturbed for a moment, returns to a state of primitive equilibrium. Whether transmission is explained by longitudinal vibration in the axiscylinder, or the chemical decomposition of pro * Maudsley, "Physiology and Pathology of the Mind," p. 167. + Idem, p. 157. toplasm, it is difficult to believe that no trace remains. We find at least in the nerve-cell an element which, by common consent, receives, stores up, and reacts. Now, an impression once received leaves its imprints. Hence, according to Maudsley, there is produced an aptitude, and with that a differentiation of the element, although we have no reason to think that originally it differed from homologous cells. "Every impression leaves a certain ineffaceable trace; that is to say, molecules once disarranged and forced to vibrate in a different way can not return exactly to their primitive state. If I brush the surface of water at rest with a feather, the liquid will not take again the form which it had before; it may again present a smooth surface, but molecules will have changed places, and an eye of sufficient power would see traces of the passage of the feather. Organic molecules acquire a greater or less degree of aptitude for submitting to disarrangement. No doubt, if this same exterior force did not again act upon the same molecules, they would tend to return to their natural form; but it is far otherwise if the action is several times repeated. In this case they lose, little by little, the power of returning to their original form, and become more and more closely identified with that which is forced upon them, until this becomes natural in its turn, and they again obey the least cause that will set them in vibration.” * It is impossible to say in what this modification consists. Neither the microscope, nor reagents, nor histology, nor histochemistry can reveal it ; but facts and reason indicate that it takes place. The second condition, which consists in the establishment of stable associations between different groups of nervous elements, has up to this time received but little attention. I do not find that contemporary authors even have realized its importance. It is, however, a necessary corollary to their thesis upon the seat of memory. Some seem to admit, at least by implications, that an organic or conscious remembrance is impressed upon a given cell, which, with its nervous filaments, has in a certain sense a monopoly of conservation and reproduction. I believe that this illusion has in part arisen through indefinite language, which leads us to regard a movement, a perception, an idea, an image, a sentiment, as one thing, as a unity. Reflection will show, however, that each of these supposed unities is composed of numerous and heterogeneous elements; that it is an association, a group, a fusion, a complexus, a *Delbœuf, "Théorie générale de la sensibilité," p. 60. |