CHAPTER VIII

THE EMBRYOLOGY OF THE SOUL

Importance of Ontogeny to Psychology--Development of the Child-Soul--Commencement of Existence of the Individual Soul--The Storing of the Soul--Mythology of the Origin of the Soul--Physiology of the Origin of the Soul--Elementary Processes in Conception--Coalescence of the Ovum and the Spermatozoon--Cell-Love--Heredity of the Soul from Parents and Ancestors--Its Physiological Nature as the Mechanics of the Protoplasm--Blending of Souls (Psychic Amphigony)--Reversion, Psychological Atavism--The Biogenetic Law in Psychology--Palingenetic Repetition and Cenogenetic Modification--Embryonic and Post-Embryonic Psychogeny

The human soul--whatever we may hold as to its nature--undergoes a continual development throughout the life of the individual. This ontogenetic fact is of fundamental importance in our monistic psychology, though the "professional" psychologists pay little or no attention to it. Since the embryology of the individual is, on Baer's principle--and in accordance with the universal belief of modern biologists--the "true torch-bearer for all research into the organic body," it will afford us a reliable light on the momentous problems of its psychic activity.

Although, however, this "embryology of the soul" is so important and interesting, it has hitherto met with the consideration it deserves only within a very narrow circle. Until recently teachers were almost the only ones to occupy themselves with a part of the problem; since their avocation compelled them to assist and supervise the formation of the psychic activity in the child, they were bound to take a theoretical interest, also, in the psychogenetic facts that came under their notice. However, these teachers, for the most part, both in recent and in earlier times, were dominated by the current dualistic psychology--in so far as they reflected at all; and they were totally ignorant of the important facts of comparative psychology, and unacquainted with the structure and function of the brain. Moreover, their observations only extended to children in their school-days, or in the years immediately preceding. The remarkable phenomena which the individual psychogeny of the child offers in its earliest years, and which are the joy and admiration of all thoughtful parents, were scarcely ever made the subject of serious scientific research. Wilhelm Preyer was the pioneer of this study in his interesting work on _The Mind of the Child_ (1881). To obtain a perfectly clear knowledge of the matter, however, we must go further back still; we must commence at the first appearance of the soul in the impregnated ovum.

The origin of the human individual--body and soul--was still wrapped in complete mystery at the beginning of the nineteenth century. Caspar Friedrich Wolff had, it is true, discovered the true character of embryonic development in 1759, in his _theoria generationis_, and proved with the confidence of a critical observer that there is a true _epigenesis_--_i.e._, a series of very remarkable formative processes--in the evolution of the foetus from the simple ovum. But the physiologists of the time, with the famous Albert Haller at their head, flatly refused to entertain these empirical truths, which may be directly proved by microscopic observation, and clung to the old dogma of "preformation." This theory assumed that in the human ovum--and in the egg of all other animals--the organism was already present, or "preformed," in all its parts; the "evolution" of the embryo consisted literally in an "unfolding" (_evolutio_) of the folded organs. One curious consequence of this error was the theory of _scatulation_, which we have mentioned on p. 55; since the ovary had to be admitted to be present in the embryo of the woman, it was also necessary to suppose that the germs of the next generation were already formed in it, and so on _in infinitum_. Opposed to this dogma of the "Ovulists" was the equally erroneous notion of the "Animalculists"; the latter held that the germ was not really in the female ovum, but in the paternal element, and that the store of succeeding generations was to be sought in the spermatozoa.

Leibnitz consistently applied this theory of scatulation to the human soul; he denied that either soul or body had a real development (_epigenesis_), and said in his _Theodicy_: "Thus I consider that the souls which are destined one day to become human exist in the seed, like those of other species; that they have existed in our ancestors as far back as Adam--that is, since the beginning of the world--in the forms of organized bodies." Similar notions prevailed in biology and philosophy until the third decade of the present century, when the reform of embryology by Baer gave them their death blow. In the province of psychology, however, they still find many adherents; they form one group of the many curious mystical ideas which give us a living illustration of the ontogeny of the soul.

The more accurate knowledge which we have recently obtained, through comparative ethnology, of the various forms of myths of ancient and modern uncivilized races, is also of great interest in psychogeny. Still, it would take us too far from our purpose if we were to enter into it with any fulness here; we must refer the reader to Adalbert Svoboda's excellent work on _Forms of Faith_ (1897). In respect of their scientific and poetical contents, we may arrange all pertinent _psychogenetic myths_ in the following five groups:

I. The myth of transmigration.--The soul lived formerly in the body of another animal, and passed from this into a human body. The Egyptian priests, for instance, taught that the human soul wandered through all the species of animals after the death of the body, returning to a human frame after three thousand years of transmigration.

II. The myth of the in-planting of the soul.--The soul existed independently in another place--a psychogenetic store, as it were (in a kind of embryonic slumber or latent life); it was taken out by a bird (sometimes represented as an eagle, generally as a white stork), and implanted in the human body.

III. The myth of the creation of the soul.--God creates the souls, and keeps them stored--sometimes in a pond (living in the form of _plankton_), according to other myths in a tree (where they are conceived as the fruit of a phanerogam); the Creator takes them from the pond or tree, and inserts them in the human germ during the act of conception.

IV. The myth of the scatulation of the soul (the theory of Leibnitz which we have given above).

V. The myth of the division of the soul (the theory of Rudolph Wagner [1855] and of other physiologists).--In the act of procreation a portion is detached from both the (immaterial) souls of the parents; the maternal contribution passes in the ovum, the paternal in the spermatozoa; when these two germinal cells coalesce, the two psychic fragments that accompany them also combine to form a new (immaterial) soul.

Although the poetic fancies we have mentioned as to the origin of the individual human soul are still widely accepted, their purely mythological character is now firmly established. The deeply interesting and remarkable research which has been made in the course of the last twenty-five years into the more minute processes of the impregnation and germination of the ovum has made it clear that these mysterious phenomena belong entirely to the province of cellular physiology (cf. p. 48). Both the female element, the ovum, and the male fertilizing body, the sperma or spermatozoa, are _simple cells_. These living cells possess a certain sum of physiological properties to which we give the title of the "cell-soul," just as we do in the permanently unicellular protist (see p. 48). Both germinal cells have the faculty of movement and sensation. The young ovum, or egg-cell, moves after the manner of an amoeba; the minute spermatozoa, of which there are millions in every drop of the seminal fluid, are ciliated cells, and swim about as freely in the sperm, by means of their lashes or _cilia_, as the ordinary ciliated infusoria (the flagellata).

When the two cells meet as a result of copulation, or when they are brought into contact through artificial fertilization (in the fishes, for instance), they attract each other and become firmly attached. The main cause of this cellular attraction is a chemical sensitive action of the protoplasm, allied to smell or taste, which we call "erotic chemicotropism"; it may also be correctly (both in the chemical and the romantic sense) termed "cellular affinity" or "sexual cell-love." A number of the ciliated cells in the sperm swim rapidly towards the stationary egg-cell and seek to penetrate into it. As Hertwig showed in 1875, as a rule only one of the suitors is fortunate enough to reach the desired goal. As soon as this favored spermatozoon has pierced into the body of the ovum with its head (the nucleus of the cell), a thin mucous layer is detached from the ovum which prevents the further entrance of spermatozoa. The formation of this protective membrane was only prevented when Hertwig kept the ovum stiff with cold by lowering the temperature, or benumbed it with narcotics (chloroform, morphia, nicotine, etc.); then there was "super-impregnation" or "poly-spermy"--a number of sperm-threads pierced into the body of the unconscious ovum. This remarkable fact proved that there is a low degree of "cellular instinct" (or, at least, of specific, lively sensation) in the sexual cells just as effectively as do the important phenomena that immediately follow in their interior. Both nuclei--that of the ovum and of the spermatozoon--attract each other, approach, and, on contact, completely fuse together. Thus from the impregnated ovum arises the important new cell which we call the "stem-cell" (_cytula_), from the repeated segmentation of which the whole polycellular organism is evolved.

The psychological information which is afforded by these remarkable facts of impregnation, which have only been properly observed during the last twenty-five years, is supremely important; its vast significance has hitherto been very far from appreciated. We shall condense the main conclusions of research in the following five theses:

I. Each human individual, like every other higher animal, is a single simple cell at the commencement of his existence.

II. This "stem-cell" (cytula) is formed in the same manner in all cases--that is, by the blending or copulation of two separate cells of diverse origin, the female ovum and the male spermatozoon.

III. Each of these sexual cells has its own "cell-soul"--that is, each is distinguished by a peculiar form of sensation and movement.

IV. At the moment of conception or impregnation, not only the protoplasm and the nuclei of the two sexual cells coalesce, but also their "cell-souls"; in other words, the potential energies which are latent in both, and inseparable from the matter of the protoplasm, unite for the formation of a new potential energy, the "germ-soul" of the newly constructed stem-cell.

V. Consequently each personality owes his bodily and spiritual qualities to both parents; by heredity the nucleus of the ovum contributes a portion of the maternal features, while the nucleus of the spermatozoon brings a part of the father's characteristics.

By these empirical facts of conception, moreover, the further fact of extreme importance is established, that every man, like every other animal, _has a beginning of existence_; the complete copulation of the two sexual cell-nuclei marks the precise moment when not only the body, but also the "soul," of the new stem-cell makes its appearance. This fact suffices of itself to destroy the myth of the immortality of the soul, to which we shall return later on. It suffices, too, for the destruction of the still prevalent superstition that man owes his personal existence to the favor of God. Its origin is rather to be attributed solely to the "eros" of his parents, to that powerful impulse that is common to all polycellular animals and plants, and leads to their nuptial union. But the essential point in this physiological process is not the "embrace," as was formerly supposed, or the amorousness connected therewith; it is simply the introduction of the spermatozoa into the vagina. This is the sole means, in the land-dwelling animals, by which the fertilizing element can reach the released ova (which usually takes place in the uterus in man). In the case of the lower aquatic animals (fishes, mussels, medusæ, etc.) the mature sexual elements on both sides are simply discharged into the water, and their union is let to chance; they have no real copulation, and so they show none of those higher psychic "erotic" functions which play so conspicuous a part in the life of the higher animals. Hence it is, also, that all the lower, non-copulating animals are wanting in those interesting organs which Darwin has called "secondary sexual characters," and which are the outcome of sexual selection: such are the beard of man, the antlers of the stag, the beautiful plumage of the bird of paradise and of so many other birds, together with other distinctions of the male which are absent in the female.

Among the above theses as to the physiology of conception the inheritance of the psychic qualities of the two parents is of particular importance for psychological purposes. It is well known that every child inherits from both his parents peculiarities of character, temperament, talent, acuteness of sense, and strength of will. It is equally well known that even psychic qualities are often (if not always) transmitted from grandparents by heredity--often, in fact, a man resembles his grandparents more than his parents in certain respects; and that is true both of bodily and mental features. All the chief laws of heredity which I first formulated in my _General Morphology_, and popularized in my _Natural History of Creation_, are just as valid and universal in their application to psychic phenomena as to bodily structure--in fact, they are frequently more striking and conspicuous in the former than in the latter.

However, the great province of heredity, to the inestimable importance of which Darwin first opened our eyes in 1859, is thickly beset with obscure problems and physiological difficulties. We dare not claim, even after forty years of research, that all its aspects are clear to us. Yet we have done so much that we can confidently speak of heredity as a _physiological function_ of the organism, which is directly connected with the faculty of generation; and we must reduce it, like all other vital phenomena, to exclusively physical and chemical processes, to the _mechanics of the protoplasm_. We now know accurately enough the process of impregnation itself; we know that in it the nucleus of the spermatozoon contributes the qualities of the male parent, and the nucleus of the ovum gives the qualities of the mother, to the newly born stem-cell. The blending of the two nuclei is the "physiological moment" of heredity; by it the personal features of both body and soul are transmitted to the new individual. These facts of ontogeny are beyond the explanation of the dualistic and mystic psychology which still prevails in the schools; whereas they find a perfectly simple interpretation in our monistic philosophy.

The physiological fact which is most material for a correct appreciation of individual psychogeny is the _continuity_ of the _psyche_ through the rise and fall of generations. A new individual comes into existence at the moment of conception; yet it is not an independent entity, either in respect of its mental or its bodily features, but merely the product of the blending of the two parental factors, the maternal egg-cell and paternal sperm-cell. The cell-souls of these two sexual cells combine in the act of conception for the formation of a new cell-soul, just as truly as the two cell-nuclei, which are the material vehicles of this psychic potential energy, unite to form a new nucleus. As we now see that the individuals of one and the same species--even sisters born of the same parents--always show certain differences, however slight, we must assume that these variations were already present in the chemical plasmatic constitution of the generative cells themselves.[17]

These facts alone would suffice to explain the infinite variety of individual features, of soul and of bodily form, that we find in the organic world. As an extreme, but one-sided, consequence of them, there is the theory of Weismann, which considers the _amphimixis_, or the blending of the germ-plasm in sexual generation, to be the universal and the sole cause of individual variability. This exclusive theory, which is connected with his theory of the continuity of the germ-plasm, is, in my opinion, an exaggeration. I am convinced, on the contrary, that the great laws of _progressive heredity_ and of the correlative _functional adaptation_ apply to the soul as well as to the body. The new characteristics which the individual has acquired during life may react to some extent on the molecular texture of the germ-plasm in the egg-cell and sperm-cell, and may thus be transferred to the next generation by heredity in certain conditions (naturally, only in the form of latent energy).

Although in the soul-blending at the moment of conception only the latent forces of the two parent souls are transmitted by the coalescence of the erotic cell-nuclei, still it is possible that the hereditary psychic influence of earlier, and sometimes very much older, generations may be communicated at the same time. For the laws of _latent heredity_ or atavism apply to the soul just as validly as to the anatomical organization. We find these remarkable phenomena of reversion in a very simple and instructive form in the alternation of generations of the polyps and medusæ. Here we see two very different generations alternate so regularly that the first resembles the third, fifth, and so on; while the second (very different from the preceding) is like the fourth, sixth, etc. (_Natural History of Creation_). We do not find such alternation of generations in man and the higher animals and plants, in which, owing to continuous heredity, each generation resembles the next; nevertheless, even in these cases we often meet with phenomena of reversion, which must be reduced to the same law of latent heredity.

Eminent men often take more after their grandparents than their parents even in the finer shades of psychic activity--in the possession of certain artistic talents or inclinations, in force of character, and in warmth of temperament; not infrequently there is a striking feature which neither parents nor grandparents possessed, but which may be traced a long way back to an older branch of the family. Even in these remarkable cases of atavism the same laws of heredity apply to the _psyche_ and to the physiognomy, to the personal quality of the sense-organs, muscles, skeleton, and other parts of the body. We can trace them most clearly in the reigning dynasties and in old families of the nobility, whose conspicuous share in the life of the State has given occasion to a more careful historical picture of the individuals in the chain of generations--for instance, in the Hohenzollerns, the princes of Orange, the Bourbons, etc., and in the Roman Cæsars.

The causal-nexus of _biontic_ (individual) and _phyletic_ (historical) evolution, which I gave in my _General Morphology_ as the supreme law at the root of all biogenetic research, has a universal application to psychology no less than to morphology. I have fully treated the special importance which it has with regard to man, in both respects, in the first chapter of my _Anthropogeny_. In man, as in all other organisms, "the embryonic development is an epitome of the historical development of the species. This condensed and abbreviated recapitulation is the more complete in proportion as the original _epitomized development_ (_palingenesis_) is preserved by a constant heredity; on the other hand, it falls off from completeness in proportion as the later _disturbing development_ (_cenogenesis_) is accentuated by varying adaptation."

While we apply this law to the evolution of the soul, we must lay special stress on the injunction to keep _both_ sides of it critically before us. For, in the case of man, just as in all the higher animals and plants, such appreciable perturbations of type (or _cenogeneses_) have taken place during the millions of years of development that the original simple idea of _palingenesis_, or "epitome of history," has been greatly disturbed and altered. While, on the one side, the _palingenetic_ recapitulation is preserved by the laws of like-time and like-place heredity, it is subject to an essential _cenogenetic_ change, on the other hand, by the laws of abbreviated and simplified heredity. That is clearly seen in the embryonic evolution of the psychic organs, the nervous system, the muscles, and the sense-organs. But it applies in just the same manner to the psychic functions, which are absolutely dependent on the normal construction of these organs. Their evolution is subject to great cenogenetic modification in man and all other viviparous animals, precisely because the complete development of the embryo occupies a longer time within the body of the mother. But we have to distinguish two periods of individual psychogeny: (1) the embryonic, and (2) the post-embryonic development of the soul.

I. _Embryonic Psychogeny._--The human foetus, or embryo, normally takes nine months (or two hundred and seventy days) to develop in the uterus. During this time it is entirely cut off from the outer world, and protected, not only by the thick muscular wall of the womb, but also by the special foetal membranes (_embryolemmata_) which are common to all the three higher classes of vertebrates--reptiles, birds, and mammals. In all the classes of amniotes these membranes (the _amnion_ and the _serolemma_) develop in just the same fashion. They represent the protective arrangements which were acquired by the earliest reptiles (_proreptilia_), the common parents of all the amniotes, in the Permian period (towards the end of the palæozoic age), when these higher vertebrates accustomed themselves to live on land and breathe the atmosphere. Their ancestors, the amphibia of the Carboniferous period, still lived and breathed in the water, like their earlier predecessors, the fishes.

In the case of these older and lower vertebrates that lived in the water, the embryonic development had the palingenetic character in a still higher degree, as is the case in most of the fishes and amphibia of the present day. The familiar tadpole and the larva of the salamander or the frog still preserve the structure of their fish-ancestors in the first part of their life in the water; they resemble them, likewise, in their habits of life, in breathing by gills, in the action of their sense-organs, and in other psychic organs. Then, when the interesting metamorphosis of the swimming tadpole takes place, and when it adapts itself to a land-life, the fish-like body changes into that of a four-footed, crawling amphibium; instead of the gill-breathing in the water comes an exclusive breathing of the atmosphere by means of lungs, and, with the changed habits of life, even the psychic apparatus, the nervous system, and the sense-organs reach a higher degree of construction. If we could completely follow the psychogeny of the tadpole from beginning to end, we should be able to apply the biogenetic law in many ways to its psychic evolution. For it develops in direct communication with the changing conditions of the outer world, and so must quickly adapt its sensation and movement to these. The swimming tadpole has not only the structure but the habits of life of a fish, and only acquires those of a frog in its metamorphosis.

It is different with man and all the other amniotes; their embryo is entirely withdrawn from the direct influence of the outer world, and cut off from any reciprocal action therewith, by enclosure in its protective membranes. Besides, the special care of the young on the part of the amniotes gives their embryo much more favorable conditions for the cenogenetic abbreviation of the palingenetic evolution. There is, in the first place, the excellent arrangement for the nourishment of the embryo; in the reptiles, birds, and monotremes (the oviparous mammals) it is effected by the great yellow nutritive yelk, which is associated with the egg; in the rest of the mammals (the marsupials and placentals) it is effected by the mother's blood, which is conducted to the foetus by the blood-vessels of the yelk-sac and the allantois. In the case of the most highly developed placentals this elaborate nutritive arrangement has reached the highest degree of perfection by the construction of a placenta; hence in these classes the embryo is fully developed before birth. But its soul remains during all this time in a state of embryonic slumber, a state of repose which Preyer has justly compared to the hibernation of animals. We have a similar long sleep in the chrysalis stage of those insects which undergo a complete metamorphosis--butterflies, bees, flies, beetles, and so forth. This sleep of the pupa, during which the most important formations of organs and tissues take place, is the more interesting from the fact that the preceding condition of the free larva (caterpillar, grub, or maggot) included a highly developed psychic activity, and that this is, significantly, lower than the stage which is seen afterwards (when the chrysalis sleep is over) in the perfect, winged, sexually mature insect.

Man's psychic activity, like that of most of the higher animals, runs through a long series of stages of development during the individual life. We may single out the five following as the most important of them:

I. The soul of the new-born infant up to the birth of self-consciousness and the learning of speech.

II. The soul of the boy or girl up to puberty (_i.e._, until the awakening of the sexual instinct).

III. The soul of the youth or maiden up to the time of sexual intercourse (the "idealist" period).

IV. The soul of the grown man and the mature woman (the period of full maturity and of the founding of families, lasting until about the sixtieth year for the man and the fiftieth for the woman--until _involution_ sets in).

V. The soul of the old man or woman (the period of degeneration).

Man's psychic life runs the same evolution--upward progress, full maturity, and downward degeneration--as every other vital activity in his organization.