The term "The Determination of Sex" is employed in two general senses in
scientific circles.
The first usage is that of the biologist, and it includes within its
scope merely the discovery and understanding of the CAUSES which
determine whether the embryo shall develop into a male or into a female.
In the discussion of the subject from this standpoint there is but
little, if any, attention given to the question of whether the sex of
the unborn child may be determined by methods under the control of man.
The biologist simply studies the causes which seem to lead to the
production of an individual of one or the other sex, without regard to
whether these causes, when discovered, may or may not be amendable to
human control.
An authority, speaking of this standpoint concerning the question
referred to, says: "We may discover the causes of storms or earthquakes,
and when our knowledge of them is sufficiently advanced we may be able
to predict them as successfully as astronomers predict eclipses, but
there is little hope that we shall ever be able to control them. So it
may be with sex; a complete understanding of the causes which determine
it may not necessarily give us the power of producing one or the other
sex at will, or even of predicting the sex in any given case. Whether we
shall ever be able to influence the causes of sex-determination cannot
as yet be foretold; at present, biologists are engaged in the less
practical, but immensely interesting, problem, of discovering what those
causes are."
The second usage of the term, includes and embraces the idea of the
voluntary determination or control of the sex of the future child, by
means of certain methods or certain systems of treatment, etc. Of recent
years, science has been devoting considerable attention to the question
of whether or not man may not be able to produce any particular sex at
will, by means of certain systems or methods of procedure. Many theories
have been evolved, and many plans and methods have been advocated, often
with the expenditure of much energy and enthusiasm on the part of the
promulgators and their adherents.
In this lesson there will be briefly presented to you the general
consensus of modern thought on the subject, with a general outline of
the favorite methods and systems advocated by the several schools of
thought concerned in the investigation.
Professor Doncaster, the well-known authority on the subject, says: "But
little progress has been made in the direction of predicting the sex of
any child, and, if possible, even less in artificially influencing the
determination of its sex. When the general principles arrived at are
borne in mind, it must be confessed that the prospects of our ever
attaining this power of control or even of prediction are not very
hopeful, but the possibility of it cannot be yet regarded as entirely
excluded. The general conclusions arrived at are that sex is determined
by a physiological condition of the embryonic cells, that this condition
is induced, at least in the absence of disturbing causes, by the
presence of a particular sex-chromosome. [A "chromosome" is a portion of
the chromatin, or substance characteristic of the nucleus of the cell,
this nucleus seemingly controlling the life-processes of the cell.] But
there is evidence, which for the present at least cannot be neglected,
that certain extraneous conditions acting on the egg or early embryo may
perhaps be able to counteract the effect of sex chromosome.
"Quite generally, then, there are two conceivable methods by which the
sex might be artificially influenced in any particular case; firstly, if
means could be found of ensuring that any particular fertilized ovum
received the required chromosomes; and, secondly, by the discovery of
methods which always effect the ovum or embryo in such a way as to
produce the desired sex. Many suggestions for applying both methods have
been made, some of which have attained considerable notoriety, but
hitherto none of them has stood the test of practical experience. In the
case of the higher animals, especially of the mammals, in which the
embryo develops in the maternal uterus until long after the sex is
irrevocably decided, it is obviously difficult to apply methods which
might influence the sex after fertilization, even if it were certainly
known that such methods were ever really effective.
"Apart from the few experiments like those of Hertwig on rearing
tadpoles at different temperatures, there have been a very few cases in
which there is even a suggestion that the sex of the fertilized egg can
be modified by environment, and the belief that this is possible has
been entirely abandoned by many of the leading investigators of the
subject. It is probable, therefore, that if it will ever be possible to
predict or determine artificially the sex of a particular child, the
means will have to be sought in some method of influencing the output of
germ-cells in such a way that one kind is produced rather than the
other. It is in this way that Heape and others interpret the results of
their investigations; they find that certain conditions affect the
sex-ratio of cells, and they explain the result by assuming that UNDER
SOME CIRCUMSTANCES MALE-DETERMINING OVA ARE PRODUCED IN EXCESS, AND
UNDER OTHER CIRCUMSTANCES, FEMALE-DETERMINING."
Professor Rumley Dawson holds to the opinion that the male-determining
and female-determining ova are discharged alternately from the ovaries.
In woman one ovum is usually discharged each month, and it is maintained
that on one month the ovum is male-determining, and in the next,
female-determining. It is obvious that exceptions must occur, for boy
and girl twins are quite common, but if the cases which support the
hypothesis are taken by themselves, and the exceptions explained away,
it is possible to make out a strong case in favor of this theory. Some
authorities hold that the right ovary produces male-determining ova, and
the left ovary female-determining, and that the two ovaries discharge an
ovum alternately, but an impartial examination of the evidence for this
belief shows that it rests on very slender foundations. Experiments on
the lower animals have shown that after the complete removal of one
ovary the female may produce young of both sexes. Women, also, have
produced children of a particular sex after the corresponding ovary has
been removed, and it is hardly possible to believe that the removal in
all these cases was incomplete. On the whole it must be concluded that
the theory is insufficiently supported by the evidence.
Another widely promulgated and vigorously supported theory is that which
holds that the sex of the future child may be determined by specific
nutrition of the mother before conception, and in some cases after
conception. Schenk's theory, advanced about 1900, attracted much
attention at the time. He based his method on the observation that a
number of women whose children were all girls all excreted sugar in
their urine, such as happens in the case of persons affected with
diabetes. From this he suspected that the physiological condition which
leads to the excretion of sugar was inimical to the development of
male-determining ova, and that males could be produced by its
prevention. He therefore recommended that those who desire a male child
should undergo treatment similar to that prescribed for diabetes for two
or three months before conception, and held that a boy would be produced
by these methods. Although this method has had considerable vogue, it
cannot be held to have been established on a scientific basis.
Doncaster says "The general conclusion with regard to man must therefore
be that if sex is determined solely by the spermatozoon there is no hope
either of influencing or predicting it in special cases. On the other
hand, there is considerable evidence that the ovum has some share in the
effect, and if this is so, before any practical results are reached it
will be necessary to discover which of two conceivable causes of
sex-determination is the true one. It is possible that there are two
kinds of ova, as well as two kinds of spermatozoa, and that there is a
selective fertilization of such a kind that one kind of spermatozoon
only fertilizes one kind of ovum, the second kind of spermatozoon the
second kind of ovum. If this should prove to be the case, it is possible
that means might be found of influencing or predicting that kind of ovum
which is discharged under any set of conditions. Secondly, it is
possible that the ova are potentially all alike, but that their
physiological condition may under some circumstances be so altered that
the sex is determined independently of the spermatozoon. * * * It is
hardly possible to avoid the conclusion that the sex of the offspring
may be influenced, at least under certain circumstances, by the mother.
The search for means of influencing the sex of the offspring through the
mother is not of necessity doomed to failure. No results of a really
positive kind have been obtained hitherto, and some of the facts point
so clearly to sex-determination by the male germ-cell alone in man and
other animals that many investigators have concluded that the quest is
hopeless; but until an adequate explanation has been given of certain
phenomena discovered in the investigation of the subject, it seems more
reasonable to maintain an open mind, and to regard the control of sex in
man as an achievement not entirely impossible of realization."
Another writer on the subject has said: "Every individual among the
higher animals, whether male or female, begins as an impregnated ovum in
the mother's body. Any such ovum contains elements of constitution from
both of its parents. In the earliest existence of this impregnated ovum,
there is a season of sexual indifference, or indecision, in which the
embryo is both male and female, having the characteristic rudiments of
each sex, only indifferently manifested. In this stage, the embryo is
susceptible of being influenced by external conditions to develop more
strongly in the one or the other direction and thus become distinctly
and permanently male or female. It is evident that this is the season in
the development of the individual in which influencing conditions and
causes must operate in deciding its sex, although it is possible in some
of the lower animals to alter the tendency of sex in the embryo from one
sex to the other, even after it has been quite definitely determined. It
is well established, in fact, that differences do not come from a
difference in the ova themselves; that is, there is not one kind of ova
from the female which becomes female, while other ova become male, for
it is possible to alter the tendency toward the one sex or the other
after the ovum has been fertilized and the embryo has begun its career
of development. This possible change in sex tendency in the embryo also
proves that sex is not decided by a difference in the spermatozoa; that
is some of the sperm cells from the father are not male, while others
are female, in their constitution.
"It is incorrect to suppose, as has been held by some theorists, that
one testicle give rise to male spermatozoa and the other to female
spermatozoa, for both male and female offspring have been produced from
the same male parent after one testicle or the other has been removed.
The same is true in cases in which either ovary has been removed from
the mother; that is, male and female offspring are produced from mothers
in whom either ovary has been removed. In like manner, the sex of
offspring is shown not to be materially affected by the comparative
vigor of the parents; thus, a stronger father than mother does not
necessarily produce one sex to the exclusion of the other. These
negative decisions are important because they simplify the solution of
the problem of sex-determination, by excluding, more or less fully,
various causes which have been supposed to operate quite forcibly in
deciding the sex of offspring. Some of the more positive agencies that
enter into the determination of sex are found (1) in the influence of
nutrition upon the embryo during its indifferent stage of sexual
development, and (2) in the constitution and general condition of the
mother before and during the early stages of pregnancy. These two
factors appear to enter more fully than any others in the decision of
the sex in offspring, and deserve the greatest consideration. The
influence of food in supplying the embryo with nourishment for its
development is, perhaps, the most potent of these determining causes."
Investigators along the line of theory indicated in the above last
quotation, i. e., the theory of sex determination by means of
nourishment of the mother and embryo, have presented a volume of reports
which demand respectful consideration. The general report may be said to
be the discovery that ABUNDANT NOURISHMENT DURING THE PERIOD OF SEXUAL
NEUTRALITY TENDS TO PRODUCE FEMALES; WHILE LACK OF ABUNDANT NUTRITION
DURING SUCH PERIOD TENDS TO PRODUCE MALES.
These experiments, of course, have been chiefly performed upon the lower
animals. The frog has been a favorite subject of such experiments--the
tadpole stage being the one selected, because in that stage there exists
a lack of sex, the stage being one of sex neutrality. Professor Yung's
celebrated experiments will illustrate this class of experiments. Here
were chosen 300 tadpoles, which when left to themselves manifested a
ratio of 57 prospective females to 43 prospective males. These were
divided into three classes of 100 tadpoles each. Each class was then fed
upon one of several kinds of nutritious diet in order to ascertain the
change in sex-tendency due to such food. The first set, with an original
ratio of femaleness of 54 to 46, were fed abundantly on beef, and the
ratio of femaleness was changed to 78 to 22. The second class, with a
ratio of femaleness of 61 to 39, were fed on fish (specially nourishing
to frogs), and the ratio changed to 81 to 19. The third class, with a
ratio of 56 to 44, were fed upon a still more nutritious diet (i. e.,
that of frogs' flesh), and the ratio was raised to 92 to 8. In short,
the experiments showed that the increase of nourishment in diet changed
every two out of three male-tendency tadpoles into females. The
experiment was held to prove that a rich diet, affording nourishment,
during the period of sexual neutrality in the embryo, tended to develop
femaleness.
The advocates of this theory also point to the instance of the bees.
With the bees, the larva of ordinary worker-bees are fed ordinary food,
and do not develop sex; while the larva which is intended to produce the
queen-bee is fed specially nutritious "royal food," and consequently
develops larger size and full female sex powers. If the queen is killed,
or dies, the hive of bees proceeds to produce a new queen by means of
feeding a selected larva with the "royal food" and thus developing full
femaleness in it. It is said by some authorities that in cases in which
some other of the larva accidently receive, through mistake, crumbs of
the "royal food," they, too, grow to an extraordinary size, and develop
fertility. This fact is held by the advocates of the nutrition theory to
go toward establishing the fact that abundant nourishment of the embryo,
during the neutral stage, tends to produce femaleness in it. They also
claim that caterpillars which are very poorly nourished before entering
into the chrysalis stage usually develop into male butterflies, while
those highly nourished in the said stage tend to become females.
Experiments on sheep have shown that when the ewes are particularly well
nourished the offspring will show a large proportion of females.
A writer, favoring the theory in question, says: "In general, it is
reasonable to infer that the higher sexual organization which
constitutes the female is to be attained in the greatest number of cases
by embryos which have superior vital conditions during the formative
period. Among human beings, some facts of general observation become
significant in the light of the foregoing inferences. After epidemics,
after wars, after seasons of privation and distress, the tendency is
toward a majority of male births. On the other hand, abundant crops, low
prices, peace, contentment and prosperity tend to increase the number of
females born. Mothers in prosperous families usually have more girls;
mothers in families of distress have more boys. Large, well-fed, fully
developed, healthy women, who are of contented and passive disposition,
generally become mothers of families abounding in girls; while mothers
who are small or spare of flesh, who are poorly fed, restless, unhappy,
overworked, exhausted by frequent childbearing, or who are reduced by
other causes which waste their vital energies, usually give birth to a
greater number of boys. As a general proposition, the facts and
inferences tend to establish the truth of the doctrine with women, that,
the more favorable the vital conditions of the mother during the period
in which the sex of her offspring is being determined, the greater the
ratio of females she will bear; the less favorable her vital conditions
at such times, the greater will be her tendency to bear males. That many
apparent exceptions occur does not disprove the general tendency here
maintained. Moreover, it is impossible to know in all cases what were
the conditions of the mother's organism at the time in which her child
was in its delicate balance between predominant femaleness and maleness;
else many cases which seemingly disprove the proposition would be found
to be forcible illustrations of its truth. Still further, it is probable
that other causes besides those here mentioned act with greater or less
effect in determining the sex of offspring."
Based upon this general theory of the relation of nutrition to
sex-determination, many methods and systems have been devised by as many
authorities, and have been followed and promulgated by as many schools.
Without going into the almost endless detail which would be necessitated
by a synopsis of these various methods and systems, it may be said that
they all consist of plans having for their object the decrease of
nutrition of the woman in cases in which male children are desired, and
the increase of nutrition in cases in which female children are sought
for. This increase or decrease in nutrition is enforced for a reasonable
period before the time selected for the conception of the child, and
also for a reasonable period after the time of conception. The decrease
in nutrition does not consist of "starvation," but rather of a "training
diet" similar to that followed by athletics, and from which dietary all
rich foods, sweets, etc., are absent. In fact, the average dietary
advocated by the "Eat and Grow Thin" writers would seem to be almost
identical with that of the "male offspring" theorists.
Many persons who have followed the methods and systems based on the
nutrition theory above mentioned claim to have been more or less
successful in the production of the particular sex desired, but many
exceptions to the rule are noted, and some writers on the subject are
disposed to regard the reported successes as mere coincidences, and
claim that the failures are seldom reported while the successes are
widely heralded. The present writer presents the claims of this school
to the attention of his readers, but without personally positively
endorsing the idea. He is of the opinion that the data obtainable is not
as yet sufficient to justify the strong claims made for the theory in
some quarters; but, at the same time, he does not hesitate to say that
there are many points of interest brought out in the presentation of the
theory, and that many thoughtful persons seem to accept the same as
reasonably well established and logical.
Another theory which has been heard of frequently of late years is that
in which it is held that the ova are expelled in alternating sex, each
month. Thus, if a male ovum is expelled in January, the February ovum
will be a female one, according to this theory. Under this theory if the
date of conception of a child be ascertained, and the sex of the child
noted at its birth, it is a simple matter to count forward from the
menstrual period following which the child was conceived, and thus
determine whether the ovum of any succeeding period is male or female.
It should be noted, however, that the periods are regulated by the lunar
months, and not the calendar months. The fact that twins of different
sexes are sometimes born would seem to disturb this theory--but not more
than any other theory of sex-determination voluntarily produced, for
that matter. The several schools explain this apparent discrepancy by
the familiar saying that "exceptions prove the rule."
Another theory of sex-determination is that which holds that when
conception occurs within a few days after the last day of menstruation,
the child will be a girl; and that when conception occurs at a later
period, the child will be a boy. Methods and systems based upon this
theory are also reported as being reasonably successful in producing
satisfactory results. But, inasmuch as there appears to be a great
difference in individual women in this respect (even according to the
claims of this school of sex-determination), it would seem that it would
be difficult to proceed with certainty in the matter in most cases. One
of the writers advocating this method, says: "Conception within five
days after the end of the menstrual period is almost certain to produce
a girl child; within five days to ten days, it may be either a boy or a
girl; from ten to fifteen days, it is almost sure to be a boy; from
eighteen to twenty-five days is the period of probable sterility, in
which conception is extremely unlikely to occur."
In conclusion, it may be said that Nature undoubtedly has certain rules
of sex-determination which govern in these cases; and that it is
possible if not indeed probable that these rules may some day be
discovered by man, and turned to account; but that it is very doubtful
whether the secret has as yet been solved by the investigators. The
writer may be pardoned for suggesting that, in his opinion, if the
discovery is ever made it will likely be found to be very simple--so
simple that we have probably overlooked it because it was in too plain
sight to attract our attention. Nature's methods are usually very
simple, when once discovered. She hides her processes from man by making
them simple, it would seem.