Chapter M: L. H (3)

This law is referred to by M. Ribot as one of the causes of deviation from heredity, and he speaks of it as "transformation." As examples of transformation of heredity, Ribot refers to fixed ideas in the progenitor, which may become in the descendants "melancholy, taste for meditation, aptitude for the exact sciences, energy of will, etc.;" the mania of progenitors may be changed in the descendants into "aptitude for the arts, liveliness of imagination, quickness of mind, inconsistency in desires, sudden and variable will." "Just as real insanity," says Moreau of Tours, "may be hereditarily reproduced only under the form of eccentricity, may be transmitted from progenitors to descendants only in modified form, and in more or less mitigated character, so a state of simple eccentricity in the parent--a state which is no more than a peculiarity or a strangeness of character--may in the children be the origin of true insanity. Thus in transformations of heredity we sometimes have the germ attaining its maximum intensity; and again, a maximum of activity may revert to the minimum."[84:A]

It should be borne in mind, as mentioned by Von Krafft-Ebings,[84:B] that everything which debilitates the nervous system and the generative powers of the parents, "be it immaturity or too advanced old age, previous debilitating diseases (typhus, syphilis), mercurial treatment, alcoholic and sexual excesses, overwork, etc., may give rise to neuropathic constitutions, and thereby indirectly to every possible nervous disease in the descendants."

TELEGONY.--There is one remarkable phenomenon, spoken of by various writers as _telegony_, which has an important bearing on the subject of the transmission of acquired characters, and shows the action of prenatal influence in an unexpected form. It is referred to by Professor Romanes, when he says, "It has not unfrequently been observed, at any rate in mammals, that when a female has borne progeny to a male of one variety, and subsequently bears progeny to a male of another variety, the younger progeny presents a more or less unmistakable resemblance to the father of the older one."[85:A] This curious fact was considered, in relation to plants especially, by Darwin, who affirms, as quoted by Romanes, that it is of the highest theoretical importance, as "The male element not only affects, in accordance with its proper function, the germ, but at the same time various parts of the mother-plant, in the same manner as it affects the same parts in the seminal offspring from the same two parents. We thus learn that an ovule is not indispensable for the reception of the influence of the male element."

The curious phenomenon of telegony is not limited, however, to plants. Mr. Herbert Spencer drew attention, in _The Contemporary Review_ for March, 1893, to a case which has long been known to horsebreeders, and which may be said to have become classic. The facts were brought, by the Earl of Morton, to the attention of the Royal Society of Great Britain, as long ago as the year 1820. The Earl, who possessed a male quagga, said, in a letter to the President: "I tried to breed from the male quagga and a young chestnut mare of seven-eighths Arabian blood, and which had never been bred from; the result was the production of a female hybrid, now five years old, and bearing, both in her form and in her colour, very decided indications of her mixed origin. I subsequently parted with the seven-eighths Arabian mare to Sir Gore Ouseley, who has bred from her by a very fine black Arabian horse. I yesterday morning examined the produce, namely, a two-year-old filly and a one-year-old colt. They have the character of the Arabian breed as decidedly as can be expected, where fifteen-sixteenths of the blood are Arabian; and they are fine specimens of that breed; but both in their colour and in the hair of their manes they have a striking resemblance to the quagga. Their colour is bay, marked more or less like the quagga in a darker tint. Both are distinguished by the dark line along the ridge of the back, the dark stripes across the forehead, and the dark bars across the back part of the legs." Mr. Spencer refers to an analogous case of the influence of a wild boar over the subsequent progeny of a domestic sow, and it now appears that such effects are not so uncommon as the scientific world has supposed.

Professor Romanes made particular enquiries on this subject of professional and amateur breeders of animals, and he says most of his correspondents "are quite persuaded that it is of frequent occurrence, many of them regard it as a general rule, while some of them go so far as to make a point of always putting a mare, bitch, etc., to a good pedigree male in her first season, so that her subsequent progenies may be benefited by his influence, even though they be engendered by inferior sires."[87:A] His own more modest conclusion is that the evidence he obtained "is enough to prove the fact of a previous sire asserting his influence on a subsequent progeny, although this fact is one of comparatively rare occurrence."

The English Darwinian met with only one case in which the offspring of a woman by a second husband, who was a white man, showed the influence of her first husband, who was a negro. Mr. Herbert Spencer would seem to have been more successful. In _The Contemporary Review_ for May, 1893, Mr. Spencer gives the result of his own enquiries as to the effect on a white woman's subsequent progeny of a previous union with a negro, and he quotes the opinion of a "distinguished correspondent," that information given to him many years ago was to the effect that "the children of white women by a white father had been _repeatedly_ observed to show traces of black blood, in cases where the woman had previous connexion with [i. e., a child by] a negro." Mr. Spencer refers also to Professor Marsh as authority for such a case, and to the opinion of several medical professors who assured him, through Dr. W. J. Youmans, that the alleged result "is generally accepted as a fact." He gives as authoritative testimony the following statement by Dr. Austin Flint, taken from his "Text-book of Human Physiology:" "A peculiar and, it seems to me, an inexplicable fact is, that previous pregnancies had an influence upon offspring. This is well known to breeders of animals. If pure blooded mares or bitches have been once covered by an inferior male, in subsequent fecundations the young are likely to partake of the character of the first male, even if they be bred with males of unimpeachable pedigree. What the mechanism of the influence of the first conception is, it is impossible to say; but the fact is incontestable. The same influence is observed in the human subject. A woman may have, by a second husband, children who resemble a former husband, and this is particularly well marked in certain instances by the color of the hair and eyes. A white woman who has had children by a negro may subsequently bear children to a white man, these children presenting some of the unmistakable peculiarities of the negro race."

This phenomenon would alone seem to answer the question of the transmission of acquired characters in the affirmative, for its explanation is to be found in the facts brought out by Darwin, as to the action of foreign pollen on the structure of the mother plant; in relation to which Professor Romanes remarks: "When one variety fertilizes the ovules of another not unfrequently the influence extends beyond the ovules to the ovarium, and even to the calyx and flower-stalk, of the mother plant. This influence, which may affect the shape, size, colour, and texture of the somatic tissues of the mother, has been observed in a large number of plants belonging to many different orders."[89:A] May we not have here the explanation of the fact, which has frequently been pointed out, that husband and wife show a tendency to grow like each other, both physically and mentally, the resemblance after a long married life being sometimes very striking?

POWER OF HEREDITY.--The most important fact brought out in the discussion of the possibility of the transmission of acquired characters is the power of heredity. If organisms did not reproduce their own special characteristics, there could be no fixity of form and no order in organic nature. Nevertheless, if there were no change by individual modification or divergence, in whatever way this may be rendered permanent in the race, there could be no evolution. Hence we can say, with Dr. Eimer, "Any one who thus completely renders allegiance to the supremacy of the principles of the unity of the organic world, who rejects everything which contradicts that principle, cannot help admitting that in truth, as I assert, the ultimate origin of the various kinships in the animal and vegetable kingdom is to be traced to individual differences, and that the difference between the former, like the latter, must be essentially determined by external conditions, by the modification of organic growth."

The causes of diversity which interfere with the action of heredity may operate, as we have seen, at the moment of conception, or subsequent to conception. The former class of causes is of great importance, in accordance with the principle, laid down by M. Ribot, of the disproportion of effects to causes, and it is essential, therefore, if children are to be well-born, that their parents should be careful that at the moment of procreation they are fitted for the performance of so serious an act. Mr. J. F. Nisbet in his "Marriage and Heredity" (page 126), well observes, "Twins usually bear a closer resemblance to each other than to their brothers and sisters born at a different period; and the reason generally assigned is that they are conceived under precisely similar conditions. If so, it follows that the difference existing between ordinary members of a family is due to their being born at considerable intervals of time and therefore under changed conditions on the part of their parents."

SOBRIETY IN THE FATHER.--Especially does it concern the father, who is the most active agent in reproduction, to see that he is then in a fit condition. This is quite apart from the question of the diseased condition of the organism treated of by Dr. Von Krafft-Ebings, and refers to temporary rather than to continuing causes. Sobriety is in this connection of great importance, and, as appears from a passage, already quoted, in Xenophon, was insisted on at the time of procreation, by the ancients.

Zeigler points out, as quoted by Dr. Eimer, that "substances taken up from without, as, for example, poisons, are brought by the blood to the sexual cells, and others produced in the body are conveyed to the sexual organs."[91:A] It is suggested that alcohol has such an effect, and there can be no doubt that a tendency to the drinking habit may be implanted in a child by a parent intoxicated at the time of procreation, with the possibility of its leading to other evils in succeeding generations, ending in the early extinction of the family. Nisbet refers to several cases of this character, and remarks (page 112) that, "There is a limit to the transmission of abnormal characters, either in an original or in a disguised form. Always striving after perfection, or rather uniformity of type, Nature either purifies a race of its physical and moral defects, or, if the type be too vicious, exterminates it, as in the case of the Caesars, the Stuarts, and many other historical families." Doutrebente came to the conclusion, however, that insanity--and doubtless it is true of other conditions--may be worked out of a family by the infusion of healthy blood, except where both parents were insane, in which case their offspring will become extinct.

The law of Leviticus (chap. x, verse 9) provides, under penalty of death, that the priests should not drink wine or strong drink before going into the tent of meeting. The more stringent regulations provided by this law in relation to intercourse between Jehovah and His people require physical and moral perfection in those who approach the deity, and they may be studied with advantage at the present day by those who wish to aid in the perfecting of the race. The man who had a blemish was not allowed to go near the altar of sacrifice, that the sanctuary might not be profaned; and the sanctuary of the human organism should no less be preserved from profanation.

SACREDNESS OF PARENTAGE.--It would be well if the sacred act of procreation were performed more often in the spirit of the ancients, who regarded marriage as a sacred institution, designed not only for the perpetuation of the race, but also for the carrying on of the religion of the domestic hearth. The first-born child especially was considered to have been sent by the gods, and care was taken, therefore, that it should be well-born. Prayer and offerings were made to the spirits before the nuptial bed was approached, and everything was done to ensure the gift they were asked for should be in every respect worthy of them. Among the ancient Hebrews the first-born of "all that openeth the womb" was dedicated to Jehovah (Exodus xxxiv, 19), and hence the rights of the eldest son could not be defeated by his father: "for he is the beginning of his strength" (Deut. xxi, 17).

The disturbance of uterine existence between conception and birth is that which has engaged most attention, and the fact that such disturbances can take place requires that the expectant mother should be protected from anything that can so act on her own organism as to prevent the due operation of the law of heredity. The precautions taken by primitive peoples in relation to food may have some foundation in fact, and any food should be avoided by the enceinte woman which will injuriously influence the system, or give rise to organic disturbances that may affect the blood by which the embryo is nourished. Emotional disturbances are to be no less avoided, as through the nervous system they act on the blood itself. How far the action of the emotions can influence the physical organism has become a moot question with psychologists, who now seem inclined to think that "movements are not caused by the emotions, but are aroused reflexly by the object." Thus, if the sight of a disagreeable object affects by reflex action the muscular system of the mother, it will arouse in her a concomitant emotion, which being transmitted to the embryo may act on its muscular system, leaving the impression as a birthmark, which may be regarded as a reflection from the cerebral nerve center of the mother, whether emotion is the cause or effect of muscular movement.

If the unborn child can be affected injuriously by disturbances of the mother's environment, it is reasonable to suppose that the child can be influenced in the opposite direction by making that environment as conducive to the normal activity of the material organism as possible. The story of Jacob and Laban, referred to at the beginning of this chapter, affords an important lesson as to the surroundings with which the wife should be provided. The bedchamber itself may become a means of influencing offspring for good or evil, and hence it should contain only what is agreeable to the senses, and capable of giving rise to pleasant imaginings. Especially should this be the case where a woman is of a highly sensitive nature. Impressions received from without depend largely for their force and influence, however, on the condition of the receptive mind, and beautiful surroundings cannot make up for the want of inward harmony. A happy and contented mind is the best guarantee that the due action of the law of heredity will not be disturbed at the time of conception or afterwards. Thus, bickerings between husband and wife must have a disturbing effect, especially if carried into the bedchamber. The sage of old said: "Let not the sun go down upon thy wrath," and parents should make it a point of duty, for the sake of their future offspring, never to let the disputes of the daytime--if unfortunately they occur--be carried into the night. The bedchamber is the place for mental as well as physical repose.

The surest guarantee against the occurrence of conditions which may injuriously affect the future offspring, either at the time of procreation, or during the subsequent period of gestation, is to be found in the general life of the parents. This will give the general impress which affects the disposition of the child as a whole, and it will show what are the conditions of the family life under the influence of which it was born. The nature of the "home" is thus an important factor in determining that of the offspring, and it will necessarily be a reflection of the general character of those on whom it depends. A noble life in the parent will bear fruit in the physical, intellectual and moral character of the child, and although this is true in relation to the father as well as to the mother, it is doubly true as to the latter, seeing that the mother alone is the bearer and nourisher of offspring during the period of gestation. During this period the child acquires probably many of the characters which it inherits from its mother, and the maternal influence may thus be extended to the period of lactation. The importance attached to fosterage, where this practice became an established custom, as with the early Irish and Arabs, would seem to prove that the characteristics of the nurse were to some extent transmitted to the child with the milk. The early Arabs regarded the milk-tie as constituting a real unity of flesh and blood between the foster mother and the foster child, and between foster children, so much so as to be a bar to marriage.

SELF-CONTROL.--One very serious matter which should be kept in mind by an expectant mother is the duty of exercising self-control. The influence of this principle in relation to the general life and conduct has been repeatedly pointed out, and it is referred to by Jennie Chandler in _The Journal of Hygiene_ for August, 1895, where we are told: "The power of self-mastery is believed by scientists to be the last one acquired by the human race in the process of evolution, and the last powers acquired are not so firmly fixed in our natures as some which have been longer in our possession. The result is, it becomes deranged more readily than more fixed forces. In many cases, self-control has never been acquired at all, and so the person can only partly master himself. As a rule, children have little of this power. They are like animals. Little by little, as they grow older, it grows, and in some it becomes so well developed that it is almost perfect. In others, like music in those who never acquire it, or any other faculty, it never becomes a potent factor in life."

Dr. Chandler adds, "Woman as well as man needs to learn self-mastery. With a large amount of feeling in her nature, it is very hard for her to do it, but she should try. Too many of us go through life never making any effort to be our own masters. We give way to caprices, whims, feelings, follies, far more than is good for our health. Hysteria gives us a good example of the loss of self-control. Any uncontrolled passion gives an equally vivid example. Men and women often say they can't govern themselves; that is admitting they have defects of character which are their masters. They ought to make effort and see if they are not mistaken. The worst effect of lack of self-control are on the health. It allows every kind of bad habit in eating, drinking, dressing, sleeping, to gain possession of the person, and the result is a weak instead of a strong character."

Considering the effect which the organic disposition of the mother has on the future offspring, it is evident that whether a child shall have the power of self-control depends very largely on the mother herself, and it is all-important, therefore, that she should have and exercise that power herself. As Dr. Chandler remarks, "No matter how much you have been to school, how many college degrees you have, you are not educated till you have a reasonable control of your own nature, and can direct your own lives rather than have them directed for you by your feelings and emotions." This truth obtains fresh significance when we consider that a woman's conduct affects the direction not only of her own life, but the lives of her future children, and possibly of succeeding generations.

Although much has yet to be done to prove the actual effects on offspring of the conduct of its parents, enough is known to establish the fact that both the general disposition and the particular conduct of father or mother may interfere with the orderly action of the law of heredity. This law ensures the inheritance of race and individual characters; but when these are good, a noble life will cause the tendencies towards good to be still further strengthened in offspring, and if they are evil, then the disposition will receive an inclination in the opposite direction, or, at least, the further development of evil will be arrested. On the other hand, a degrading life will produce bad effects on offspring, causing deterioration of the organic disposition and strengthening the tendency to evil it may have inherited, or weakening its tendencies towards the good.

FOOTNOTES:

[57:A] "Heredity." By Th. Ribot (New York: D. Appleton & Co., 1875), p. 201.

[59:A] "The Origin of the Fittest." By E. D. Cope (D. Appleton & Co., New York). Page 408.

[65:A] "Pioneering in New Guinea." By James Chalmers. 1887. Page 165.

[66:A] "Development of Kinship and Marriage." Page 264.

[67:A] "Researches into the Early History of Mankind." Page 292.

[71:A] Cope's "Origin of the Fittest." (Redway, London. 1889.) Page 407.

[72:A] "Organic Evolution." Translated by J. T. Cunningham, M. A. (London, Macmillan & Co., 1890.) Page 86.

[73:A] "Examination of Weismannism." The Open Court Publishing Co., Chicago. 1893.

[77:A] _The Contemporary Review_, September, 1893.

[79:A] "Organic Evolution." Translated by J. T. Cunningham, M. A. Page 13.

[80:A] "Organic Evolution," page 176.

[84:A] "Organic Evolution," page 211.

[84:B] Op. cit., page 201.

[85:A] "Examination of Weismannism," page 77.

[87:A] "Examination of Weismannism," page 22.

[89:A] "Examination of Weismannism," page 79.

[91:A] "Organic Evolution," page 187.

HEREDITY AND EDUCATION.

_A Lecture delivered before the Brooklyn Ethical Association._

In presenting the subject of heredity and its relation to education, it seems to me best to consider first what is meant by the term, and after this the views held on the subject by our leading evolutionists, when its relation to education will be easier and, I hope, more satisfactory.

In common parlance, heredity is the transmission of any trait or peculiarity from the parent to the offspring, as the color of the hair, the form of the nose, the tones of the voice; or any disease, or any special character that may exist in either parent.

If a horse has a star on its forehead like one of its ancestors, we say it is due to heredity. If an ox has color marks on its body like its parent, it is a case of heredity. If a human being has a disease which his ancestors had, very often he declares he inherited it from them, even if it be only a common catarrh. But this is a narrow view of the subject, and does not include all that a biologist means when he uses this word.

By heredity he understands the production from a fertilized ovum of an individual, with all the general characteristics of structure and function of body and brain of the species to which it belongs. It means that the offspring, however much they may vary in general characters, will always be of the same species as the parents. The offspring of dogs will be dogs; of wolves, wolves; of negroes, negroes, and of white men, white men. Anything less is not heredity in its full sense.

Darwin, whom we all love and honor, says: "The whole subject of inheritance is wonderful," and in this he but voices the universal sentiment of those who have given any serious consideration to it. Let me try to show you how wonderful it is by an illustration. From very ancient times the horse has been the constant companion of man. This animal, with his splendid muscular system, the most perfect, perhaps, of any creature, has for his food and shelter, and not always the best of these, rendered mankind almost infinite service. Now, every horse that has ever been born into the world began life as a minute ovum, which under the microscope presents no appearance of a horse, or any other animal, and, strange to say, this ovum is, to all appearance, like the ovum of other animals, and no amount of study, without knowing its origin, can decide whether it will develop as a dog, an ox, a horse or a man. After, however, it has gone through the process of gestation, this apparently simple egg becomes an animal of a very complex nature, with heart, lungs, brain, eyes, ears, mouth, stomach, and blood vessels, all where they should be and ready to perform their functions; with mental traits of a peculiar kind which adapt him to the service which man requires. Nay more: In the process of the evolution of the horse, little by little he has changed in various ways, and many, if not all of these changes in his bodily constitution and in his mental characteristics, which have been found useful or made him more serviceable to man, his greater docility, his increased size, his enormous strength and speed, his wonderful beauty, through a wise selection and the weeding out of the unfit on the part of the breeder, have been transmitted through heredity to his offspring, so that today only a paleontologist can tell us if he finds the remains of a primitive horse, that it belongs to the same class of animals as the horse of our time.

THEORIES.--Our theories of heredity will depend on the extent of our knowledge, and especially our knowledge of embryology. In the last century knowledge on this subject was very meagre, especially that part of embryology which could only be studied with the microscope; consequently the views of scientists and others of that time were exceedingly crude. The most important was that of Malphigi and Bonnet, who maintained that the miniature animal existed in the egg; that fertilization by the male element simply furnished it with food for growth, and that this was added to and stored up in its interstices. Cuvier, Haller and Leibnitz adopted substantially these views. The latter found them to support his opinion that everything was the result of growth from monads, and that there was no such thing in all nature as generation.

Such a theory was very simple, but it explained nothing except the bare production of offspring. It gave no clue to their endless variations, nor to the fact that they often resembled the father more than the mother. According to this theory the offspring should resemble the mother, as the complete individual is formed by her and should be in her image.

Leeuwenhock, one of the early microscopists, by the aid of his lenses, opened a new world to mankind, and discovered the sperm cells to be active, living, moving elements, and he gave a death-blow to the belief that the perfect organism exists in the ovum; but he went to the opposite extreme, and maintained that it exists in the male cell and that it is only fed and developed by the female. Even today we find in a vague way both these theories held by educated persons.

We are indebted to Harvey in the early part of the eighteenth century for advocating the view held by Aristotle, now known as _Epigenesis_, and combatting the view of growth from a miniature, but already perfectly formed animal, to a visible one. Epigenesis consists in the successive differentiation from the relatively homogeneous elements as found in the egg, to the complicated parts and structure as seen in the offspring.

According to Huxley, this work of Harvey alone would have entitled him to recognition as one of the founders of biological science, had he not immortalized himself as the discoverer of the circulation of the blood.

Not long after Harvey's publication, Casper Frederick Wolf established the theory of epigenesis upon a firm foundation, where it still remains.

The doctrine of _epigenesis_ has very much complicated the whole question of heredity. No wonder even so great a mind as that of Darwin exclaimed, "The whole subject is wonderful." How can an egg, which in structure is comparatively simple, an aggregation of cells, not one of which bears the slightest resemblance to any organ in the body, develop into the perfect individual? How can this egg, formed in special organs, develop other organs than those like the ones in which it was formed? How can sexual cells develop brain cells, with their wonderful modes of action?

We cannot explain the philosophy of heredity without being able to answer these questions; but difficult as is the problem, our biologists have made various attempts at an explanation. I cannot go over all the various speculations, but only those most intimately connected with the subject will be mentioned.

The first is Darwin's own attempt at an explanation by the theory of _pangenesis_, or genesis from every part. He saw the necessity of having in the sexual cells some power or force to represent the other organs and functions of the body, else how could these organs be formed in the embryo? Pangenesis was supposed to be accomplished as follows: Every organ through its cells gives off _gemmules_. These are inconceivably small, too small for any microscopical vision; also inconceivably great in numbers, and with great power of growth and multiplication. They pass from the various organs in which they are formed to the special sex organs for generating the sexual cells; some of them are stored up as representatives of the various organs from which they have been given off. The consequence is that every egg has in it something from every organ in the body of both parents which is able, during gestation, to develop into that organ.

According to this theory, for instance, if no gemmules are given off from the brain, then no brain can be developed from the egg, and so of other organs. As in a representative government, all parts of the country send representatives to the capitol to do the bidding of the people, so every organ of the body sends representatives to the sexual cells to form their respective organs; without them these organs would not be formed.

There are many objections to pangenesis, but they need not be named here. It occurred to Galton, whose studies in heredity have been more prolific of good than those of any other man, to test it by practical experiment. If these gemmules are circulating in the blood of animals before being stored up in the sexual cells, by transfusing blood from one variety of any species to another it ought to affect the offspring of this other. For his test cases he chose eighteen silvergrey rabbits which breed true, and into their bodies he transfused the blood of other different varieties, in several cases replacing one-half of this fluid. There were eighty-six offspring bred at once from these silvergrey rabbits, and all true silvergreys. The theory did not work. But if it did not work in practice, it certainly worked on the intellects of biologists everywhere, exactly what Darwin wished; it set them to thinking. It acted as a ferment, so to say, and brought forth a rich harvest in speculation if not in actual knowledge.[106:A]

CONTINUITY OF THE GERM-PLASM.--The only other theory which I shall mention is that of Weismann, which has been before the public for more than a decade, and it is safe to say it has produced a more profound impression upon biologists than all others. It has its basis in what he calls _continuity of the germ-plasm_. By the germ-plasm is meant that part of the germ cell containing all the chemical and physical properties, including the molecular structure, which enables it to become, under appropriate conditions, a new individual of the same species as the parents. In it lies hidden all the characteristics both of the species and of the future individual. In it lies all the phenomena of heredity. It is the product of the coalescence of the male and female elements requisite for reproduction. Only, however, in the nuclear substance is to be found the hereditary tendencies. Now, this germ-plasm is _continuous_, that is to say, it contains not only material from both parents, but from grandparents and greatgrandparents, and so on indefinitely. This germ-plasm is exceedingly minute in quantity, but has great power of growth. Not all is used up in the production of any individual, but some is left over and stored up for the next generation. The germ-plasm might be represented as a long creeping root, from which arise at intervals all the individuals of successive generations. The amount of ancestral germ-plasm in each fertilized ovum is calculated in the same way that stock breeders calculate the amount of blood of any ancestor running in any individual. For instance: The germ-plasm contributed by the father and mother is each one-half; each grandparent one fourth, and so on. Ten generations back each ancestor contributes only one part in one thousand and twenty-four parts. This continuity has by some been called the immortality of the germ-plasm. Theoretically, the original Adam and Eve have contributed an infinitesimal part. This probably explains why there is so much of the original Adam in most of us. By it we are able to explain that wonderful fact of _atavism_, or the appearance of characters from a remote ancestor in offspring. Some of the germ-plasm from this ancestor by some means has had an opportunity to grow rapidly and contribute more than its share in the production of the individual in which it appears.

It also enables us to explain the fact that no two individuals are quite alike, but that there is constant variation. Each person is the product of a multitude of ancestors, and the germ-plasm which produced them is never mixed, in quite the same proportion, nor do the different parts grow with quite the same vigor.

It was on this theory of the continuity of the germ-plasm that Weismann built his doctrine of the non-transmission of acquired characters. On this subject he says: "Hence it follows that the transmission of acquired characters is an impossibility, for if the germ-plasm is not formed anew in each individual, but is derived from that which preceded it, its structure, and above all, its molecular constitution, cannot depend upon the individual in which it happens to occur, but such an individual only forms, as it were, the nutritive soil at the expense of which it grows, while the latter possessed its character from the beginning, that is, before the commencement of growth." Of this, however, I will speak later.

A RATIONAL VIEW OF HEREDITY.--I might continue giving other theories of heredity--Haeckel's, for instance--or the metaphysical theory, but it is hardly necessary. I do not accept in full any of them. Their authors, it seems to me, have not worked along the lines of evolution, but have gone further than was necessary into the fields of speculation. Darwin, in his theory of Pangenesis, admitted this frankly, and yet he clung to the idea with great tenacity. If we take the unicellular organisms which multiply by division, we may see that heredity is simple. One unicellular individual growing larger than is convenient, divides into two. Each is like the other. It could hardly be different. Reproduction by spores or buds is practically the same thing. The spores or buds are minute particles of the parent organism. When it comes to the coalescence of the germ and sperm elements from two organisms, the phenomena become more complicated, and it is still more so as the animal rises in the scale of creation; but I believe the processes of organic evolution have gone on so slowly that the sexual cells have acquired the power to transmit the whole organism without the necessity of the germ-plasm being continued from parent to offspring indefinitely, and also without the aid of pangenesis.

The egg has acquired a tendency to develop in a certain direction. Just how we cannot tell, further than to say that it was probably the result of variation first and natural selection selecting out those variations most suitable. It is this tendency to vary that gives rise to many of the phenomena of heredity. The subject is, for the present, beyond our power to settle satisfactorily, and so hypotheses must be resorted to. The sexual cells, comparatively simple in anatomical structure, must be highly complex in their molecular structure; and the more highly evolved the organism, the more complex becomes this molecular structure. If it were possible to study this molecular structure we should be able to understand the whole subject far better than is possible now. But this is not possible, and there is little hope that we shall ever be able to accomplish it.

HEREDITY AND THE EDUCATION OF CHILDREN.--The next question which comes up for consideration is that of the education of children and its relation to heredity. This brings us at once to the problem as to whether acquired characters are transmitted to offspring or not. If acquired characters are transmitted, the relation of heredity to education must be very close and important. If acquired characters are not inherited, then heredity and education have a very different relation. That acquired characters are transmitted has long been believed. It was the belief of Lamarck. He tried to explain the structure of the organism by this principle. The illustration of the long neck of the giraffe is familiar to every one. It originated by the constant stretching of this part to obtain food from the trees. In times of scarcity, he had to exert himself in this way still more to reach the higher branches. The young of the giraffe had longer necks than their parents because of the efforts of the latter in this way. So the keen sight of birds, it was argued, was acquired in the same manner. The hawk had to exercise his eyes most vigorously to discern his prey at a distance, and his offspring inherited this keenness of sight acquired by the exercise of his ancestors.

Darwin believed that the effects of the exercise of any part were transmitted. He says: "We may feel assured that the inherited effects of the use and disuse of parts will have done much in the same direction with natural selection in modifying man's structure of body."

We may say that this belief has been held by the common people, uneducated in science. They not unfrequently get at truths in a rude way long before the scientists do. Many parents tell us their children are strongly influenced by some particular occupation of the mother during pregnancy. So strong is this belief, that many mothers are in our times trying to influence the character of their unborn children by special modes of life, by cultivating music or art, or science, in order to give the child a love for these pursuits.

It is by Herbert Spencer that this has been most ably presented. Indeed, he holds that there is no explanation of evolution without the transmission of the effects of the use and disuse of parts. His words are: "If there has been no transmission of acquired character there has been no evolution."

He also says: "If we go back to the genesis of the human type from some lower type of primates, we see that while the little toe has ceased to be of any use for climbing purposes, it has not come into any considerable use for walking or running. It is manifest that the great toes have been immensely developed since there took place the change from arboreal to terrestrial habits. A study of the mechanism of walking shows why this has happened. Stability requires that the line of direction--the vertical line, let fall from the center of gravity--shall fall within the base, and the walking shall be brought at each step within the area of support, or so near that any tendency to fall may be checked at the next step. A necessary result is that _if_ at each step the chief stress of support is thrown on the outer side of the foot, the body must be swayed so that the line of direction may fall within the outside of the foot, or close to it; and when the next step is taken it must be similarly swayed in an opposite direction, so that the outer side of the foot may bear the weight. That is to say, the body must oscillate from side to side, or waddle. The movement of the duck when walking shows what happens when the points of support are far apart. This kind of movement conflicts with efficient locomotion. There is a waste of muscular energy in making these lateral movements, and they are at variance with the forward movement. We may infer, then, that the developing man profited by throwing the stress as much as possible on the inner side of the feet, and was especially led to do this when going fast, which enabled him to abridge the oscillations, as indeed we see it now in the drunken man. Then there was thrown a continually increasing stress upon the inner digits as they progressively developed from the efforts of use, until now the inner digits, so large compared with the outer, bear the greater part of the weight, and being relatively near one another render needless any swaying of the body from side to side in walking. But what has meanwhile happened to the outer digits? Evidently as fast as the great toes have come more and more into play and the small ones have gone more and more out of play, dwindling for--how long shall we say?--perhaps 100,000 years." In other and simpler words, the great toe of man has wonderfully developed since he began to walk upright. This has been from greater use, and the transmission of the effects of this use to offspring. The small toe has decreased in size proportionately. This we can reasonably infer has been the result of disuse, the effects of which were also transmitted to offspring.

A still more remarkable illustration of the effects of use and disuse is seen in the sense of touch in different parts of the body. Prof. Weber, in his laboratory for experimental psychology, has worked out this difference most minutely. He finds that by taking a pair of compasses, the points of which are less than one-twelfth of an inch apart, the end of the forefinger is not able to distinguish more than one point. Going to the middle of the back we have the least discriminating power in the skin, for the points must be separated two and one half inches before the nerves can decide that there are two. Any one may test this on himself. Between these extremes we have many differences. The end of the nose has four times as great power of discrimination as the forehead. When we come to the tip of the tongue, we find it far excels any part of the body in its power of tactual discrimination, it being twice that of the forefinger. In every case we find there is greatest delicacy of touch in those parts where this sense has been most exercised. The tongue is being constantly exercised on our food, on the roof of the mouth, the teeth, etc. It is rarely idle. There is in man no advantage for his survival, Mr. Spencer asserts, by having such a sensitive tongue. He could get on just as well without it. He regards it as a case where the exercise of a function has exalted it remarkably, and this exaltation has been transmitted to offspring. Natural selection, he thinks, is not sufficient to account for it. Natural selection only preserves those characters which will give their possessor some advantage in the struggle for existence.

Still another argument is drawn from the whale. This monster once lived, it is believed, partly on land, probably on low land near water, and must have been smaller than now. It had hind legs; but since it has lived continuously in the water its tail has so developed as to make a far better organ of locomotion, and the legs have dwindled from disuse, so that now there is only a remnant left, and this is hidden beneath the skin. The tail has become more efficient from use, and this has been transmitted so that all whales are born with well developed tails. The legs have dwindled for want of use until they have almost disappeared; and this effect of disuse has also been transmitted to offspring.

Another illustration is furnished by Havelock Charles, an English surgeon, who has spent much time among the Punjab tribes in India, and studied them anthropologically. His account is given in "The Journal of Anatomy," in a paper on the structure of the skeletons of these people. It appears they have facets on the bones, fitting them for the sitting posture. These do not develop after birth, but are seen in the fetus. It seems hardly possible that these facets could have any other origin except by transmission after being acquired by ages of use of sitting posture.

Another argument is drawn from the coadaptation of parts. We know that the male sheep, likewise the goat, the stag, and the males of many other animals, have large horns. They are supposed to be useful in fighting with rivals in order to secure as large a number of females as possible. Now these large horns require at the same time a greater development of the bones of the head to hold them, also larger and stronger vertebrae of the neck and back, and larger muscles of these parts to maintain and use them effectively. In other words, there must be coadaptation of all the parts, otherwise these larger horns would be an incumbrance and useless. Now, if we accept the theory of the inheritance of acquired characters, this is all simple. The use of the head in butting against other males exercises all these parts simultaneously, and they develop equally and at the same time. If, however, inheritance has no part in the matter, then we must fall back on variation in the germ-plasm and natural selection for an explanation; but it is difficult or, as Spencer says, impossible to conceive of variation producing large and heavy horns on these animals and at the same time coadaptation of all the other parts to hold and use them. Sometimes coadaptation does not take place, as in the common brook crab, familiar to every country boy. Its foreclaws or fingers are out of all proportion to the rest of the leg, and its awkwardness is well known. The lobster is another case. Even in human beings we have instances of non-coadaptation, as where the head and brain are out of proportion to the size of the body, or the reverse. I need not multiply instances.

Now, if acquired characters are transmitted, any system of training which exists for a considerable time must necessarily appear in the structure of the body and in the character. If the training is not in accord with the laws of evolution, it causes the race to deviate from the true line of progress, and by just so much hinder advancement. If, on the other hand, our systems of education conform to correct principles, progress is advanced by them.

Quite recently an entirely new theory has grown up, opposed to Lamarckianism, and the theory of the transmission of acquired characters. It has been before the world little more than a decade and has made remarkable progress, though it is too soon to say it has been established beyond dispute. Prof. Weismann, its author, is well equipped as a biologist to maintain and defend it. I have already stated briefly his theory of heredity, namely, that the germ-plasm is continuous from parent to offspring. This necessitates a remodeling of commonly accepted views, an entire giving up of the Lamarckian belief that use and disuse have their effect on progeny. If the germ-plasm continues from one generation to another, then it must already have been formed, or at least provided for, even before the birth of the parents. They may modify it, through growth and nutrition, but not through exercise of any function. Prof. Weismann went at the demonstration of his views in a thoroughly scientific way by the making of experiments on living animals and the collection of facts. From his experiments it is now pretty well established that wounds and injuries, which he considers to be acquired characters, are not transmitted. No matter for how many generations you cut off the tails of dogs, cats, horses or sheep, the effects of this removal do not appear in the progeny. Most parents have some mark on the body, received in early life, some cut or bruise, some scratch, but their children do not inherit them. The famous experiment of cutting off the tails of mice, for generation after generation, and then breeding from them was one of Weismann's methods of substantiating the theory that acquired character is not inherited. The offspring of these mutilated mice had as long tails as if those of their parents had not been removed. The explanation is, the germ-plasm was not in any way affected by the bodily mutilation. The practice of the Flathead Indian is another case. The children of parents whose heads have been artificially flattened are not affected by it. The small feet of Chinese women, made so by binding them and preventing their growth, may also be mentioned.

INTELLECTUAL ACQUIREMENTS.--Not to depend on such evidence, however, he adduces that of a very different character, namely, the non-transmission of intellectual acquirements. Language is an example. Although human beings have been communicating their thoughts to each other from very ancient times by speech, yet every child has to learn how to do this for itself. No matter how many languages the parents master, their children have to go over all the ground the parents did, make all the toil and effort to learn to speak. The children of the most gifted linguists, if brought up without coming in contact with those who can teach them to talk, will never learn a single word. There are, it is claimed, a few cases on record of children who never acquired their natural tongue because they had lived among animals and not among human beings. They learned to make the same vocal sounds the animals did, no more. The environment in this case was everything, the parental acquirements nothing.

Music, like language, is also an acquired character, and it is probably not transmitted. Our musical geniuses are not the children of great musicians, but in most cases the reverse. They seem to spring into existence from lowly sources, or at least from parents whose advantages for a musical education have been very limited, though generally they have had good health, and a climatic environment of a favorable kind. Great musical talent usually dies out in any family in a few generations, no matter how much it is cultivated, or, if it does not die out entirely, it becomes mediocre; and yet the opportunities of the children of great musicians, and the ambition of their parents for its culture, are usually very favorable.

INSTINCT.--In accepting the theory of the non-transmission of acquired characters, it becomes necessary to give up prevailing views of the origin of instinct. According to the old belief it was a gift of God, and not acquired by any effort on the part of its possessor. In speaking of the instinct of bees, Sidney Smith says: "_Providence has done it._ There are the bees, there is the comb, and the honey, get rid of it or find some other explanation if you can."

The early evolutionists changed all this, and made instinct the inheritance of an oft-repeated act. The young kitten, as soon as old enough, hunts for a mouse and catches it without any training. The sight of the mouse acts on its nervous system in such a way as to compel it to creep up softly, jump on it, toy and play with it, and finally kill and eat it. It would have required long practice on the part of its ancestors before so wonderful a character could have become fixed. The same is true of the setter dog.