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.