Moreover, an engram may be revived by the enfeebled return of the primary irritating agent which produced it, or by an analogous enfeebled irritation. Thus, the sight of a photograph will revive the image of a known person. A certain kind of maize imported for a long time into Norway and influenced in that country during many generations by the sun of the long summer days, finally accelerated its time of maturation. When imported again to the south of Europe it first preserved its faculty of accelerated maturation in spite of the shortness of the days (Schübeler). Semon gives a series of analogous examples which show how engrams repeated during several generations accumulate and end by becoming ecphoriated when they have acquired enough power.
Engrams may be associated simultaneously in space, such as those of sight. But they may also be associated in succession, such as those of hearing and of ontogeny. Simultaneous engrams are associated in every direction with the same intensity. Successive engrams, on the contrary, are associated more strongly forwards than backwards, and have only two poles. In the succession a b, a acts more strongly on b than b on a. In the successions of engrams it often happens that two or more analogous engrams are associated in a manner more or less equivalent to a preceding engram. Semon calls this phenomenon dichotomy, trichotomy, etc. But in the successions, two engrams cannot be ecphoriated simultaneously. Hence the phenomenon which Semon names alternating ecphoria; that is sometimes one, sometimes the other of the constituent engrams, for example, of a dichotomy, which arrives at ecphoria. Similarly, the engram of the ecphoriated dichotomy is most often that which has been previously most often repeated.
In the laws of ontogeny and heredity alternating ecphoria plays an important part. The branch less often repeated remains latent and the other only is ecphoriated. But certain combinations which reënforce the latent branch or paralyze the other may induce ecphoria of the first to the second generation.
Semon also shows that the phenomena of regeneration in the embryo, as well as those of the adult, obey the law of the mneme.
Homophony.—The terms engram and ecphoria correspond to the well-known introspective phenomena in psychology of memory and the association of ideas. Engrams are thus ecphoriated. At the time of such phenomena every mnemic irritation of the engrams vibrates simultaneously with the state of synchronous irritation produced by a new irritation. This simultaneous irritation is named by Semon homophony. When a partial discord is produced between the new irritation and the mnemic irritation, the organism always tends to reëstablish homophony (harmony). This is seen in psychological introspection by activity of attention; in embryology by the phenomenon of regeneration; and in phylogeny by that of adaptation.
Relying on these convincing facts, Semon shows that irritative actions are only localized at first in their zone of entry (primary zone); but that afterward they irradiate or vibrate, gradually becoming weaker in the whole organism (not only in the nervous system, for they also act on plants). By this means, engraphia, although infinitely enfeebled, may finally reach the germinal cells. Semon then shows how the most feeble engraphias may gradually arrive at ecphoria, as the result of numerous repetitions (in phylogeny after innumerable generations). This is how the mnemic principle allows us to conceive the possibility of an infinitely slow heredity of characters acquired by individuals, a heredity resulting from prolonged repetition.
The facts invoked by Weismann against the heredity of acquired characters lose nothing of their weight by this, for the influence of crossing (conjugation) and selection transforms the material organic forms in an infinitely more rapid and intense manner than individual mnemic engraphias. The latter, on the other hand, furnish the explanation of the mutations of de Vries, which appear to be only sudden ecphoria of accumulated long engraphic actions.
The way in which Semon studies and discusses the laws of the mneme in morphology, physiology and psychology, is truly magisterial, and the perspective which opens out from these new ideas is extensive. The mneme, with the aid of the energetic action of the external world, acts on organisms by preserving them and combining them by engraphia, while selection eliminates all that is ill-adapted, and homophony reëstablishes the equilibrium. The irritations of the external world, therefore, furnish the material for the construction of organisms. I confess to having been converted by Semon to this way of conceiving the heredity of acquired characters. Instead of several nebulous hypotheses, we have only one—the nature of mnemic engraphia. It is for the future to discover its origin in physical and chemical laws.
I must refer my readers to Semon's book, for this volume of 343 pages, filled with facts and proofs, cannot be condensed into a few paragraphs.
Each Cell bears in itself Ancestral Energy. As we have already seen, the germinal, cells are not the only ones which possess the energies of all the characters of the species. On the contrary it becomes more and more certain, from further investigation, that each cell of the body bears in itself, so to speak, all the energies of the species, as is distinctly seen in plants. But in all the cells which are not capable of germinating, these energies remain incapable of development. It results that such energies, remaining virtual, have no practical importance.