“7th. On the basis of the hypothesis above mentioned we have shown that the law of Weber-Fechner admits of a rational physico-chemical interpretation, and that the result thus obtained, provided the hypothesis above mentioned be an exact representation of facts, is that the intensity of the sensation is at each instant proportionate to the mass of the product of the autocatalyzed chemical reaction above mentioned and, consequently, to the extent of the trace of memory.”
While it is easy to understand that auto-catalysis may take part in the chemical process which underlies the performance of simple volition, as inferred by Robertson,[[60]] and perhaps reproduction in the memory process, it is difficult to understand how such a chemical action can explain conservation. The problem is not that of acceleration of an action, but of something like the storing up of energy.
Rignano[[61]] has proposed an hypothesis according to which the cells of the nervous system are to be considered as so many accumulators, analogous to electric accumulators or storage batteries. “The similarities and differences which nerve currents present in comparison with electric currents warrant us in assuming in nerve currents some of the properties of electric currents, and in attributing at the same time to the first other properties which the electric do not possess, provided these qualities are not incompatible with the others.”
Now, according to the hypothesis, the specific nervous current set up by any stimulus forms and deposits in the nucleus of the cells (through which the current flows) a substance which adds itself to the others already there without changing them and which is capable, under appropriate conditions, of being discharged and restoring the same specific current by which it was produced. Each cell thus becomes what Rignano calls an elementary nervous accumulator. He points out that “both the conception of accumulators of nervous energy in tension, and that of accumulators of a specific nervous energy constituting their specific irritability,” which the hypothesis includes, are not new but “an ordinary conception very generally employed.”... “The only new thing which the above definition includes is the hypothesis that the substance, which is thus capable of giving as a discharge a given nervous current, was produced and deposited only by a nervous current of the same specificity, but in the inverse direction, and could have been produced and deposited only by such a current.” "In just this capacity of restoring again the same specificity of nervous current as that by which each element had been deposited one would look for the cause of the mnemonic faculty, in the widest sense, which all living matter possesses. And further the very essence of the mnemonic faculty would consist entirely in this restitution.“
”The specific elementary accumulators (previously termed specific potential elements) are thus susceptible now of receiving a third name, namely, that of mnemonic elements." “The preservation of memories is to be ascribed to the accumulations of substance,” while “the reawakening of these memories consists in the restitution of the same currents [by discharge of the substance] as had formerly constituted the actual sensation or impression.”
By this hypothesis Rignano explains not only memory but the inheritance of acquired characters and the whole process of specialization of cells, all of which phenomena are special instances of such elementary accumulators of organic energy being formed and discharged.
Any attempt, with our present knowledge, to postulate particular kinds of chemical or physical changes in the nervous system as the theoretical residua of physiological dispositions left by psychological experiences must necessarily be speculative. And any hypothesis can only have so much validity as may come from its capability of explaining the known facts. It is interesting, however, to note some of the directions which attempts have taken to find a solution of the problem. For the present it is best to rest content with the theory to which we have been led, step by step, in our exposition, namely, that conservation is effected by some sort of physiological residua. This theory, of course, is an old one, and has been expressed by many writers. What we want, however, is not expressions of opinion but facts supporting them. It would seem as if the facts accumulated in recent years by experimental and abnormal psychology all tended to strengthen the theory, notwithstanding an inclination in certain directions to seek a psychological interpretation of conservation.
Some minds of a certain philosophical bent will not be able to get over the difficulty of conceiving how a psychological process can be conserved by the physical residuum of a physiological process. But this is only the old difficulty involved in the problem of the relation between mind and brain of which conservation is only a special example. That a mind process and a brain process are so intimately related that either one determines the other there is no question. It is assumed in every question of psycho-physiology. The only question is the How. I may point out in passing, but without discussion, that if we adopt the doctrine of panpsychism for which I have elsewhere argued[[62]]—namely, that there is only one process—the mental—in one and the same individual, and that what we know as the physical process is only the mode of apprehending the mental process by another individual; if we adopt this doctrine of monism the difficulty is solved. In other words, the psychical (and consciousness) is reality, while matter (and physical process) is a phenomenon, the disguise, so to speak, under which the psychical appears when apprehended through the special senses. According to this view in their last analysis all physical facts are psychical in nature, although not psychological (for psychological means consciousness), so that physiological and psychical are one. To this point I shall return in another lecture.
Neurograms.—Whatever may be the exact nature of the theoretical alterations left in the brain by life’s experiences they have received various generic terms; more commonly “brain residua,” and “brain dispositions.” I have been in the habit of using the term neurograms to characterize these brain records. Just as telegram, Marconigram, and phonogram precisely characterize the form in which the physical phenomena which correspond to our (verbally or scripturally expressed) thoughts, are recorded and conserved, so neurogram precisely characterizes my conception of the form in which a system of brain processes corresponding to thoughts and other mental experiences is recorded and conserved.[[63]]
Of course it must not be overlooked that such neurograms are pure theoretical conceptions, and have never been demonstrated by objective methods of physical research. They stand in exactly the same position as the atoms and molecules and ions and electrons of physics and chemistry, and the “antibodies” and “complements” of bacteriology. No one has seen any of these postulates of science. They are only inferred. All are theoretical concepts; but they are necessary concepts if the phenomena of physical, chemical, and bacteriological science are to be intelligible. The same may be said for brain changes if the phenomena of brain and mind are to be intelligible.