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dark though flushed with scarlet lichens-casting their quiet shadows across its restless radiance, the fountain underneath them filling its marble hollow with blue mist and fitful sound, and over all-the multitudinous bars of amber and rose, the sacred clouds that have no dark ness, and only exist to illumine, were seen in fathomless intervals between the solemn and orbed repose of the stone pines, passing to lose themselves in the last, white blinding lustre of the measureless line where the Campagna melted into the blaze of the sea."

MARY WOOD-ALLEN, M. D.
ROSE M. WOOD-ALLEN.

Heredity

HE two factors which produce human character and measure human endeavor are inheritance and environment. The latter is education in the broadest sense. It includes the food and caresses of infancy, the temperature and barometric pressure of the atmosphere during life, the associations of childhood, and the thoughts of old age; in short, the influence of every external force which in any way affects the body or mind of the child or adult. Education in the narrower sense is merely our efforts to concentrate and select these forces, to prevent the action of some of them, and to direct the action of others, both in the order of their sequence and in the degree of their activity.

Control of the other factor,-inheritance,-is not yet possible in human society. It would seem, at first thought, therefore, that the phe nomena of heredity could have but little practical value for teachers and parents. This conclusion is, however, so far from the truth that it is doubtful whether any other class of facts is as important to the trainer of children. It is true that society cannot directly match the parents of successive generations, but it is all the more necessary that educators should know how to bring the forces of environment to bear upon the tendencies of heredity, both to restrain the undesirable ones and to further those which contribute to the welfare of individual and race. Besides, it is certain that a more extensive knowledge of the facts of heredity will influence the mating of many intelligent persons and thus give the human race some of the advantages now experienced by domestic animals through artificial selection.

We are much surprised to find children who differ essentially from their parents. It is true

we expect stronger resemblances in body than in mind, and in both we are satisfied with agreement in essentials, in the larger features and more general characteristics, though we are not disturbed by the reappearance of insignificant body marks or mental idiosyncrasies. We expect that children will resemble their parents, and from this fact alone teachers and parents should receive many hints in the training of the young. Knowledge of the individual child may be greatly increased by personal acquaintance with the parents and with the home life of the children.

The enormous influence of our ancestors on our lives is often a source of anxiety as well as sometimes a cause of pride. The inheritance of certain diseases (or, strictly speaking, the tendency to certain diseases) is an established fact so frightful in its possible consequences as to revive the ancient awe of fate. But surely it is best to know the truth and thus to avoid the dangers as far as possible. Even when too late to prevent the unfortunate combination of causes the severity of the effects may be diminished by the introduction of suitable factors in education (environment). The extreme cases of mismating are fortunately rare and their influence seldom outlives a few generations. But perfect men and women are not to be found, and no family is without weak points.

A knowledge of the elementary facts of heredity may lead parents to such a study of themselves as will enable them to save their children much sorrow and pain. It will modify the methods of teachers in the management of pupils and will finally do away with the dogma of uniformity in course of study.

We do not now attempt to make roadsters, draft horses, and trick mules out of all colts and by the same kinds of feed and training. Sometime we shall cease making business men, preachers, and clowns out of the same mass of boys by the same kind of training. It is easy to over-emphasize this analogy, and yet there is in it an important truth for parents and teachers regarding the differences of children which are more than skin deep, and which must be reckoned with as fast as knowledge and funds are available. It is not possible for us to | change the sun, but we may carry a sun-shade, İ and by other means we may destroy completely the effects of the sun on an individual life, or continue much of its influence during the entire night. Knowledge may in some degree affect

heredity itself, but in much greater degree it will counteract the influences of heredity by opposing appropriate factors of environment, and by strengthening the desirable tendencies through selective education.

Material basis of heredity.

The propagation of all kinds of life is by The propagation of all kinds of life is by means of a division of body substance. In the lowest animals there may be an equal division of the individual. Then the two parts immediately become new animals and are young. In time each may divide again. There is thus no natural death among such creatures. There is no loss of material in the death of the old, and each of the young is the direct continuation of the single parent. By assimilation of new material and by the gradual wearing out of the old elements the actual substance of the body is changed just as it is constantly changed by similar processes in the human individual during his whole life.

Among other lowest animals, instead of equal division of the body, there is a separation of a small piece of body substance which then by growth soon equals and resembles its parent. In this case the body of the parent finally dies. In both these methods of generation there is no difference of sex. The individual animals reproduce themselves without aid from other individuals of the same species. The second method (called budding) is evidently only a modification of the first (called fission), and by a further modification it becomes the type of all generation, even in the highest animals and in

man.

This change is produced by the development of two kinds of individuals in the same species and the purpose is said to be to increase variation in the species. It consists in the coale scence of two buds, one from each of two individuals of the same species, but of different These buds, the sperm from the male and the ovum from the female, are the material instruments for all the wonders of hereditary transmission. Each offspring of the higher animals and of human beings, therefore, starts with a body composed of material particles from each parent. These parent buds are each unable to develop without the assistance of the other. But it is evident that the life of the human being begins with the union of these two buds. It is also clear in a general way how the offspring comes to resemble the parents and even remoter ancestors; it is composed of the

same substance as its parents. We are so accustomed to the figurative use of words that their literal significance is often lost even when it is most essential.

These buds of parent substance forming the human germ grow by changing nutriment into body substance like that of themselves, and they develop by differentiation of organs common to their species. The germ is a single cell. Development proceeds by increase in size and by successive divisions into two, four, and many cells. The numerous cells also become different from each other as the multiplication goes on. This leads to the formation of different tissues and organs to perform the innumerable and complex functions of adult life. These are the bare facts of the material basis of heredity upon which there is no difference of opinion.

When we try to explain how the original parental buds transmit to all the cells of the new being the ancestral peculiarities we encounter some diverging views, which we may

call

Theories of heredity.

It was formerly thought by scientists, and is perhaps now believed by most persons, that the ovum, or female bud, contained a miniature body like that of the parent, complete in all respects except size, and that the sperm, or male bud, merely gave it life or induced it to commence growing. It has even been said that the mother furnished the body and the father the spirit. Literally there is no truth in this statement, for both buds are alive and both are equally powerless to develop without the other; moreover, the "spirit" of the father resides in the matter of the sperm and the spirit of the mother is also necessarily present in the matter of the ovum.

Scientists no longer believe that the germ is a reduced copy of the adult. It is a simple cell, complex enough as we are coming to know, but when compared with the adult body it is indeed a simple cell. There is no appreciable difference between the germs of the lower animals and those of man, and the first stages in the development of the germs of very unlike animals are identical in process. The agree ment of scientists on this point is followed by an important difference of view regarding the minuter means of transmitting likenesses. broad line separating the two schools is the possibility of transmitting characters acquired from its own experience during the life of the

The

use.

individual. One party affirms and the other denies this proposition. There is no difference of opinion concerning the effect of environment on the individual. The occupation, the food, the climate, the associates, the successes and failures, and indeed every insignificant experience is recognized by all as influencing the life of every person. The hands of the trench digger and those of the hay pitcher show the effects of The weakness of the pampered lap-dog illustrates the results of disuse. At first thought the casual reader will be convinced that acquired characters are transmitted to offspring, and yet he does not expect rat terriers which have had their ears trimmed, even for several generations, to produce short and sharpeared puppies, much less would he expect to find the brand of cattle already burned on newborn calves, or the ear-marks of swine apparent on young pigs.

Common observation teaches that some acquired marks are not inherited and one school of biologists maintains that no influence of the environment is transmitted to the offspring. Even if this is true it should not discourage instructors of the young; for education would then be far more essential to the individual and we already know that knowledge is not inherited. The ultimate effect of a decision of this question cannot be as important as it seems to the novices, else there would be less doubt as to the facts. It is a question of means rather than results. And yet a decision would have important bearings on educational theory and practice. It is the constant endeavor of the wise to conceive the minutest processes of nature in terms of what is already known. The mystery of life is pushed as far back as imagination can reach.

The Neo-Lamarckian view.

Characteristics acquired during the life of an individual may be transmitted to offspring. This opinion is held by some continental biologists, by Herbert Spencer, and by most American biologists. Various complex suppositions of the means by which such transmission takes place have been suggested. With the advance of our knowledge of the structure and action of the germ cell there is a convergence of views on the question of inheritance until now the two schools are agreed on all essential facts, but still differ on the hidden processes back of the facts. They are also coming more nearly together on the main question of inheritance of acquired

characters. Each side is diminishing the importance of its contention as it becomes more interested in the process of inheritance itself. So that now one side admits that many former examples of inheritance of acquired characters may be explained in other ways and the other side admits that some "tiny modifications" may be inherited. The effect is to diminish the importance of the question, and also to lessen the influence of education and experience on future generations.

The Neo-Darwinian view.

Characters acquired during the life of an individual cannot be transmitted to offspring. This opinion is held by Weismann, Galton, Wallace, and most other European biologists. The particular explanation of the process of inheritance which underlies this view is chiefly the work of Weismann and is called the continuity of the germ plasm. In outline it can readily be understood, and as its main features are also accepted by the other school it is worth while to obtain some conception of it.

The life of all higher animals begins in a single cell formed by the fusion of two parent cells. Development of the individual takes place by growth and division of this cell, and by differentiation of the resulting cells. A portion of this original cell does not change, but is set apart and forms the germ-plasm of the new individual, thus the germ-plasm passes from generation to generation without alteration except as it unites with the germ-plasm of the opposite sex. The bare fact of the continuity of the germ-plasm is agreed to by all biologists. They differ only as to the possibility and degree of influence on the germ cells by the other cells of the body. The Neo-Darwinians maintaining that the germ cells are isolated from all influence of body cells. They are the parents of the latter, but are not at all subject to them. This is pure hypothesis, and is an exception to the rule of mutual dependence of parts of the body upon each other. The Neo-Lamarckians deny it and affirm that the germ cells, like all other cells, are influenced by nutrition and by the condition of the blood.

"The organism is a unity; cell is often linked to cell by bridges of living matter; the blood is a common medium carrying food and waste; nervous relations bind the whole in harmony. Would it not be a physiological miracle if the reproductive cells led a charmed life unaffected even by influences which touch the very heart

of the organism? Is it unreasonable to presume that some influences of habit and conditions, of training and control, saturate the organism thoroughly enough to affect every part of it?"

"A slight change of food affects the development of the reproductive organs in a bee-grub and makes a queen out of what otherwise would have been a worker. A difference of diet causes a brood of tadpoles to become almost altogether female. There is no doubt that some (body) changes affect the reproductive cells in some way. Is it inconceivable that they affect them in such a precise way that the bodily changes may be transmitted?"

We cannot tell how these modifications take place, and until we can do so it will be denied that they actually take place at all. And yet we know that body cells do affect each other. If they affect the germ cells, which are nourished by the same blood and which are in immediate protoplasmic connection with the body cells, there can be no doubt of the transmission of acquired characters.

The Neo-Darwinian view is so contrary to the supposed observations of everyday life that it may seem needless to mention it. Our daily "observations," however, count for little when the weight of scientific authority is opposed to them. A single example must suffice to show how the facts actually observed may be accounted for by either of two hypotheses. The long neck of the giraffe is due to its continued efforts to reach the high foliage of trees. The stretched necks of one generation are then in herited by the next generation and the process is repeated with more or less gain to the species. On the contrary, says the Neo-Darwinian, these long necks are entirely due to natural selection which gives those individuals with longest necks a decided advantage over their shorter necked fellows, especially in dry years, by en abling them to reach the branches inaccessible to the less favored ones. Long-necked individuals would thus survive and transmit the advantages to posterity. Short-necked giraffes would soon die out. And all this without any transmission of the "stretching" accomplished upon individual necks. In this manner the in heritance of every acquired character is explained away. Natural selection and the known tendency of offspring to vary from parents is sufficient to account for all cases of apparent use-inheritance. ural selection is a factor.

We know that natThen why call in an

other until it is proved that this is insufficient, or that the other is in any degree efficient?

Let us not lose our compass. Children are like their parents, but they may be made vastly different from their parents by proper environment (education). If this transformation is only for one generation it may discourage some of the world-reformers in education, but it will not seriously disturb the common educators. We have as compensation the correlative fact that if the improvements are not handed down then the backslidings of our generation are not counted up against posterity. As already stated, the truth will be found to lie somewhere between the extremes of present theories. Education probably does exert influence on future generations directly, as we know it does indirectly. But this influence is not strong enough in itself to furnish much motive for the necessary effort. We must, therefore, continue to derive our chief incentive to study and to teach from the good to the present participants, and through them to their descendants by securing better care in infancy and a better preparation for the duties of life.

The aristocracy of birth.

As we diminish the importance of inheriting acquired characteristics we recognize more clearly the value of good blood. We are also more apt to misunderstand the meaning of this term. We must come to recognize that the desirable thing in this regard is quality of blood and nerve substance. Good breeding generally means training in the forms of social congress. The training of one's ancestors has but slight influence on the fibre of one's being. Indeed, most of the finest natures of the world have sprung right from the soil. Ancestral training has generally had but little to do with the quality of their minds and hearts. In so far as this training has led to the selection of better mates and to the better training of children it has been helpful. We do not now receive the greatest amount of human energy from the so-called higher classes (that is, higher by birth).

None of this means, however, that brains are not inherited. It all means that only brains are inherited. The education, the training, the veneer, perishes with the body cells. The qual ity of the foundation upon which this temporary structure is raised is transmitted to future generations, much as it was received from ancestral sources. This foundation is essential, but it exists in the peasant as well as in the prince.

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The applications of the lessons of heredity would require a volume for presentation. A moderate understanding of the process will show the inexorableness of the laws. It will also show that the parent and educator may employ this knowledge to great advantage. It does not indicate that "the cobbler should stick to his last," much less that the children of the cobbler should attach themselves to their father's last. Neither does it mean that the aristocratic idler and parasite should continue in idleness. The children of the cobbler need the influence of the best available means of development even more than the dukelet. The life of the former will be a battle royal, that of the latter may be a fairy dream and dreams go of themselves. The "lower classes" are not yet stirred up sufficiently to allow the emergence of a tenth of the persons with fair ability. Universal education, and especially higher education, will increase this fraction in spite of a few timid and conceited college professors who fear lest they may spoil a good hodcarrier in their classrooms. It is probable that education should be adapted to its ends as well as to its material, but it is unfortunate that anyone in charge of youth should believe that education is only for the gifted. The supremely gifted don't need it. Indeed they would be injured by such as we now have to offer them; but the mediocre and the dull need the influence of most favorable environment in order to develop to their full capacity. The burdens of the world are upon these classes and they should be encouraged to strengthen themselves for endurance or avoidance.

Our conclusions from the study of heredity.

I. Any trait or tendency of body or mind may be inherited unless it was acquired during the lifetime of the parent. Marks of human species are most unerringly transmitted, then come the marks of race, of nation, and of family. The peculiarities of the individual parents as distinguished from their family resemblances are less likely to be transmitted. Though if such marks have been derived by inheritance they are apt to cling very persistently to descendants. Well marked physical features are most certain to be handed down. Complexion, color of hair and eyes, shape of head, form of nose, of ears, and of internal mouth are commonly reproduced with much resemblance to one or other of the parents. Stature and tendency to cor pulency or leanness are equally inheritable. Strength of muscles and power of endurance, especially of lungs and quality of heart, size and functional power of the stomach, in fact the actual conditions of all the important organs of the body are naturally transmitted, excepting always when these conditions have been acquired by the parent during his own lifetime. The mental powers are subject to this same law of inheritance, but are more variable because they are more complex. The temperament is most likely to be transmitted, especially when it is very marked. The taste for study, occupation, and the greater pleasures of life are often transmitted to offspring. The more complex a function is the less probability there is of its transmission. Thus the religious and moral natures of parents are inherited by children only in rare cases and in imperfect degrees. True the lack of moral character often seems to be especially persistent in the offspring of criminals, but this only proves the rule that the more complex functions are less stable and less likely to reappear in descendants. A strong derangement of the organism is much more certain to reappear than a marked delicacy of coordination which we call character or genius. In some cases the lack of normal nature is due to disease, and in other cases it is due to arrested development or to the absence of the coordinating power necessary for the finer adjustments of modern life.

The tendency to certain diseases is commonly inherited. Especially is this true of organic deficiencies. While unusual mental power is seldom retained long in one family, nothing in the whole list of mental inheritances is more certain of transmission than extreme instability

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