therefore women and mares are the only animals which admit the male
during gestation, the former for the reason stated, and mares both
because of the barrenness of their nature and because their uterus
is of superfluous size, too large for one but too small to allow a
second embryo to be brought to perfection by superfoetation. And the
mare is naturally inclined to sexual intercourse because she is in the
same case as the barren among women; these latter are barren because
they have no monthly discharge (which corresponds to the act of
intercourse in males) and mares have exceedingly little. And in all
the vivipara the barren females are so inclined, because they resemble
the males when the semen has collected in the testes but is not
being got rid of. For the discharge of the catamenia is in females a
sort of emission of semen, they being unconcocted semen as has been
said before. Hence it is that those women also who are incontinent
in regard to such intercourse cease from their passion for it when
they have borne many children, for, the seminal secretion being then
drained off, they no longer desire this intercourse. And among birds
the hens are less disposed that way than the cocks, because the uterus
of the hen-bird is up near the hypozoma; but with the cock-birds it is
the other way, for their testes are drawn up within them, so that,
if any kind of such birds has much semen naturally, it is always in
need of this intercourse. In females then it encourages copulation
to have the uterus low down, but in males to have the testes drawn up.
It has been now stated why superfoetation is not found in some
animals at all, why it is found in others which sometimes bring the
later embryos to birth and sometimes not, and why some such animals
are inclined to sexual intercourse while others are not.
Some of those animals in which superfoetation occurs can bring the
embryos to birth even if a long time elapses between the two
impregnations, if their kind is spermatic, if their body is not of a
large size, and if they bear many young. For because they bear many
their uterus is spacious, because they are spermatic the generative
discharge is copious, and because the body is not large but the
discharge is excessive and in greater measure than is required for the
nourishment wanted for the embryo, therefore they can not only form
animals but also bring them to birth later on. Further, the uterus
in such animals does not close up during gestation because there is
a quantity of the residual discharge left over. This has happened
before now even in women, for in some of them the discharge
continues during all the time of pregnancy. In women, however, this is
contrary to Nature, so that the embryo suffers, but in such animals it
is according to Nature, for their body is so formed from the
beginning, as with hares. For superfoetation occurs in these
animals, since they are not large and they bear many young (for
they have many toes and the many-toed animals bear many), and they
are spermatic. This is shown by their hairiness, for the quantity of
their hair is excessive, these animals alone having hair under the
feet and within the jaws. Now hairiness is a sign of abundance of
residual matter, wherefore among men also the hairy are given to
sexual intercourse and have much semen rather than the smooth. In
the hare it often happens that some of the embryos are imperfect while
others of its young are produced perfect.
6
Some of the vivipara produce their young imperfect, others
perfect; the one-hoofed and cloven-footed perfect, most of the
many-toed imperfect. The reason of this is that the one-hoofed produce
one young one, and the cloven-footed either one or two generally
speaking; now it is easy to bring the few to perfection. All the
many-toed animals that bear their young imperfect give birth to
many. Hence, though they are able to nourish the embryos while newly
formed, their bodies are unable to complete the process when the
embryos have grown and acquired some size. So they produce them
imperfect, like those animals which generate a scolex, for some of
them when born are scarcely brought into form at all, as the fox,
bear, and lion, and some of the rest in like manner; and nearly all of
them are blind, as not only the animals mentioned but also the dog,
wolf, and jackal. The pig alone produces both many and perfect
young, and thus here alone we find any overlapping; it produces many
as do the many-toed animals, but is cloven-footed or solid-hoofed
(for there certainly are solid-hoofed swine). They bear, then, many
young because the nutriment which would otherwise go to increase their
size is diverted to the generative secretion (for considered as a
solid-hoofed animal the pig is not a large one), and also it is
more often cloven-hoofed, striving as it were with the nature of the
solid-hoofed animals. For this reason it produces sometimes only
one, sometimes two, but generally many, and brings them to
perfection before birth because of the good condition of its body,
being like a rich soil- which has sufficient and abundant nutriment
for plants.
The young of some birds also are hatched imperfect, that is to say
blind; this applies to all small birds which lay many eggs, as crows
and rooks, jays, sparrows, swallows, and to all those which lay few
eggs without producing abundant nourishment along with the young, as
ring-doves, turtle-doves, and pigeons. Hence if the eyes of swallows
while still young be put out they recover their sight again, for the
birds are still developing, not yet developed, when the injury is
inflicted, so that the eyes grow and sprout afresh. And in general the
production of young before they are perfect is owing to inability to
continue nourishing them, and they are born imperfect because they are
born too soon. This is plain also with seven-months children, for
since they are not perfected it often happens that even the
passages, e.g. of the ears and nostrils, are not yet opened in some of
them at birth, but only open later as they are growing, and many
such infants survive.
In man males are more often born defective than females, but in
the other animals this is not the case. The reason is that in man
the male is much superior to the female in natural heat, and so the
male foetus moves about more than the female, and on account of moving
is more liable to injury, for what is young is easily injured since it
is weak. For this same reason also the female foetus is not
perfected equally with the male in man (but they are so in the
other animals, for in them the female is not later in developing
than the male). For while within the mother the female takes longer
in developing, but after birth everything is perfected more quickly in
females than in males; I mean, for instance, puberty, the prime of
life, and old age. For females are weaker and colder in nature, and we
must look upon the female character as being a sort of natur
al
deficiency. Accordingly while it is within the mother it develops
slowly because of its coldness (for development is concoction, and it
is heat that concocts, and what is hotter is easily concocted); but
after birth it quickly arrives at maturity and old age on account of
its weakness, for all inferior things come sooner to their
perfection or end, and as this is true of works of art so it is of
what is formed by Nature. For the reason just given also twins are
less likely to survive in man if one be male and one female, but
this is not at all so in the other animals; for in man it is
contrary to Nature that they should run an equal course, as their
development does not take place in equal periods, but the male must
needs be too late or the female too early; in the other animals,
however, it is not contrary to Nature. A difference is also found
between man and the other animals in respect of gestation, for animals
are in better bodily condition most of the time, whereas in most women
gestation is attended with discomfort. Their way of life is partly
responsible for this, for being sedentary they are full of more
residual matter; among nations where the women live a laborious life
gestation is not equally conspicuous and those who are accustomed to
work bear children easily both there and elsewhere; for work
consumes the residual matter, but those who are sedentary have a great
deal of it in them because not only is there no monthly discharge
during pregnancy but also they do no work; therefore their travail
is painful. But work exercises them so that they can hold their
breath, upon which depends the ease or difficulty of child-birth.
These circumstances then, as we have said, contribute to cause the
difference between women and the other animals in this state, but
the most important thing is this: in some animals the discharge
corresponding to the catamenia is but small, and in some not visible
at all, but in women it is greater than in any other animal, so that
when this discharge ceases owing to pregnancy they are troubled
(for if they are not pregnant they are afflicted with ailments
whenever the catamenia do not occur); and they are more troubled as a
rule at the beginning of pregnancy, for the embryo is able indeed to
stop the catamenia but is too small at first to consume any quantity
of the secretion; later on it takes up some of it and so alleviates
the mother. In the other animals, on the contrary, the residual matter
is but small and so corresponds with the growth of the foetus, and
as the secretions which hinder nourishment are being consumed by the
foetus the mother is in better bodily condition than usual. The same
holds good also with aquatic animals and birds. If it ever happens
that the body of the mother is no longer in good condition when the
foetus is now becoming large, the reason is that its growth needs more
nourishment than the residual matter supplies. (In some few women
it happens that the body is in a better state during pregnancy;
these are women in whose body the residual matter is small so that
it is all used up along with the nourishment that goes to the foetus.)
7
We must also speak of what is known as mola uteri, which occurs
rarely in women but still is found sometimes during pregnancy. For
they produce what is called a mola; it has happened before now to a
woman, after she had had intercourse with her husband and supposed she
had conceived, that at first the size of her belly increased and
everything else happened accordingly, but yet when the time for
birth came on, she neither bore a child nor was her size reduced,
but she continued thus for three or four years until dysentery came
on, endangering her life, and she produced a lump of flesh which is
called mola. Moreover this condition may continue till old age and
death. Such masses when expelled from the body become so hard that
they can hardly be cut through even by iron. Concerning the cause of
this phenomenon we have spoken in the Problems; the same thing happens
to the embryo in the womb as to meats half cooked in roasting, and
it is not due to heat, as some say, but rather to the weakness of
the maternal heat. (For their nature seems to be incapable, and
unable to perfect or to put the last touches to the process of
generation. Hence it is that the mola remains in them till old age
or at any rate for a long time, for in its nature it is neither
perfect nor altogether a foreign body.) It is want of concoction that
is the reason of its hardness, as with half-cooked meat, for this
half-dressing of meat is also a sort of want of concoction.
A difficulty is raised as to why this does not occur in other
animals, unless indeed it does occur and has entirely escaped
observation. We must suppose the reason to be that woman alone among
animals is subject to troubles of the uterus, and alone has a
superfluous amount of catamenia and is unable to concoct them; when,
then, the embryo has been formed of a liquid hard to concoct, then
comes the so-called mola into being, and this happens naturally in
women alone or at any rate more than in other animals.
8
Milk is formed in the females of all internally viviparous
animals, becoming useful for the time of birth. For Nature has made it
for the sake of the nourishment of animals after birth, so that it may
neither fail at this time at all nor yet be at all superfluous; this
is just what we find happening, unless anything chance contrary to
Nature. In the other animals the period of gestation does not vary,
and so the milk is concocted in time to suit this moment, but in
man, since there are several times of birth, it must be ready at the
first of these; hence in women the milk is useless before the
seventh month and only then becomes useful. That it is only
concocted at the last stages is what we should expect to happen also
as being due to a necessary cause. For at first such residual matter
when secreted is used up for the development of the embryo; now the
nutritious part in all things is the sweetest and the most
concocted, and thus when all such elements are removed what remains
must become of necessity bitter and ill-flavoured. As the embryo is
perfecting, the residual matter left over increases in quantity
because the part consumed by the embryo is less; it is also sweeter
since the easily concocted part is less drawn away from it. For it
is no longer expended on moulding the embryo but only on slightly
increasing its growth, it being now fixed because it has reached
perfection (for in a sense there is a perfection even of an embryo).
Therefore it comes forth from the mother and changes its mode of
development, as now possessing what belongs to it; and no longer takes
that which does not belong to it; and it is at this season that the
milk becomes useful.
The milk collects in the upper part of the body and the breasts
because of the original plan of the organism. For the part above the
&nb
sp; hypozoma is the sovereign part of the animal, while that below is
concerned with nourishment and residual matter, in order that all
animals which move about may contain within themselves nourishment
enough to make them independent when they move from one place to
another. From this upper part also is produced the generative
secretion for the reason mentioned in the opening of our discussion.
But both the secretion of the male and the catamenia of the female are
of a sanguineous nature, and the first principle of this blood and
of the blood-vessels is the heart, and the heart is in this part of
the body. Therefore it is here that the change of such a secretion
must first become plain. This is why the voice changes in both sexes
when they begin to bear seed (for the first principle of the voice
resides there, and is itself changed when its moving cause changes).
At the same time the parts about the breasts are raised visibly
even in males but still more in females, for the region of the breasts
becomes empty and spongy in them because so much material is drained
away below. This is so not only in women but also in those animals
which have the mammae low down.
This change in the voice and the parts about the mammae is plain
even in other creatures to those who have experience of each kind of
animal, but is most remarkable in man. The reason is that in man the
production of secretion is greatest in both sexes in proportion to
their size as compared with other animals; I mean that of the
catamenia in women and the emission of semen in men. When,
therefore, the embryo no longer takes up the secretion in question but
yet prevents its being discharged from the mother, it is necessary
that the residual matter should collect in all those empty parts which
are set upon the same passages. And such is the position of the mammae
in each kind of animals for both causes; it is so both for the sake of
what is best and of necessity.
It is here, then, that the nourishment in animals is now formed
and becomes thoroughly concocted. As for the cause of concoction, we
may take that already given, or we may take the opposite, for it is