Chapter 10
CHAPTERS VII AND VIII OF BOOK II OF GENERATION OF ANIMALS BY ARISTOTLE TRANSLATED BY ARTHUR PLATT. THIS LIBRIVOX RECORDING IS IN THE PUBLIC DOMAIN. VII. In viviparous animals, as said before, the embryo gets its growth through the umbilical cord.
For, since the nutritive power of the soul, as well as the others, is present in animals, it straightway sends off this cord like a root to the uterus. The cord consists of blood vessels in a sheath, more numerous in the larger animals as cattle and the like, one in the smallest, two in those of intermediate size. Through this cord the embryo receives its nourishment in the form of blood, for the uterus is the termination of many blood vessels.
all animals with no front teeth in the upper jaw, and all those which have them in both jaws, and whose uterus has not one great blood-vessel running through it, but many close together instead, all these have in the uterus the so-called cotyledons, with which the umbilical cord connects, and is closely united, for the vessels which pass through the cord run backwards and forwards, between embryo and uterus, and split up into smaller vessels all over the uterus.
Where they terminate, there are found the cotyledons. Their convexity is turned towards the uterus, the concavity towards the embryo. Between uterus and embryo are the chorion and the membranes. As the embryo grows and approaches perfection, the cotyledons become smaller and finally disappear when it is perfected. For nature sends the sanguineous nutriment for the embryo into this part of the uterus, as she sends milk into the breasts. And because the cotyledons are
gradually aggregated from many into a few, the body of the cotyledon becomes like an eruption or inflammation. So long as the embryo is comparatively small, being unable to receive much nutriment, they are plain and large. But when it has increased in size, they fall in together. But most of the animals which have front teeth in both jaws and no horns have no cotyledons in the uterus. But the umbilical cord runs to meet one blood vessel which is large and extends
throughout the uterus. Of such animals some produce one young at a time, some more than one, but the same description applies to both these classes. This should be studied with the aid of the examples drawn in the anatomy and the inquiries. For the young, if numerous, are attached each to its umbilical cord, and this to the blood-vessel of the mother. They are arranged next to one another along the stream of the blood-vessel as along a canal, and each embryo
is enclosed in its membranes and chorion. Those who say that children are nourished in the uterus by sucking some lump of flesh or other are mistaken. If so, the same would have been the case with other animals. But as it is, we do not find this, and this can easily be observed by dissection. Secondly, all embryos alike, whether of creatures that fly or swim or walk, are surrounded by fine membranes separating them from the uterus, and from the fluids which are formed
in it. But neither in these themselves is there anything of the kind, nor is it possible for the embryo to take nourishment by means of any of them. Thirdly, it is plain that all creatures developed in eggs grow when separated from the uterus. Natural intercourse takes place between animals of the same kind. However, those also unite whose nature is near akin, and whose form is not very different, if their size is much the same, and if the periods of gestation are equal.
In other animals such cases are rare, but they occur with dogs and foxes and wolves. The Indian dogs also spring from the union of a dog with some wild dog-like animal. A similar thing has been seen to take place in those birds that are amative as partridges and hens. Among birds of prey, hawks of different form are thought to unite, and the same applies to some other birds. Nothing worth mentioning has been observed
in the inhabitants of the sea, but the so-called rhinobatus especially is thought to spring from the union of the rhine and batus. And the proverb about Libya, that Libya is always producing something new, is said to have originated from animals of different species uniting with one another in that country. For it is said that because of the want of water all meet at the few places where springs are to be found, and that even different kinds unite in consequence.
Of the animals that arise from such union, all except mules are found to copulate again with each other, and to be able to produce young of both sexes. But mules alone are sterile, for they do not generate by union with one another or with other animals. The problem why any individual, whether male or female, is sterile, is a general one. For some men and women are sterile, and so are other animals in their several kinds, as horses and sheep. But this kind,
that of mules, is universally so. The causes of sterility in other animals are several. Both men and women are sterile from birth, when the parts useful for union are imperfect, so that men never grow a beard, but remain like eunuchs, and women do not attain puberty. The same thing may befall others as their years advance, sometimes on account of the body being too well nourished. For in men who are in too good condition, and women who are too fat,
the seminal secretion is taken up into the body, and the former have no semen, the latter no catamemia. At other times, by reason of sickness, men emit the semen in a cold and liquid state, and the discharges of women are bad and full of morbid secretions. Often, too, in both sexes, the state is caused by injuries in the parts and regions contributory to copulation. Some such cases are curable, others incurable, but the subjects especially remain sterile if anything
of the sort has happened in the first formation of the parts in the embryo. For then are produced women of a masculine, and men of a feminine appearance, and in the former the cataminae do not occur. In the latter the semen is thin and cold. Hence it is, with good reason, that the semen of men is tested in water to find out if it is infertile. For that which is thin and cold is quickly spread out on the surface, but the fertile sinks to the bottom, for that which is
well concocted is hot indeed, but that which is firm and thick is well concocted. They test women by pessaries to see if the smells thereof permeate from below upwards to the breath from the mouth, and by colors smeared upon the eyes to see if they color the saliva. If these results do not follow, it is a sign that the passages of the body through which the cataminae are secreted are clogged and closed. For the region about the eyes is, of all the hand, that most nearly
connected with the generative secretions. A proof of this is that it alone is visibly changed in sexual intercourse, and those who indulge too much in this are seen to have their eyes sunken in. The reason is that the nature of the semen is similar to that of the brain, for the material of it is watery, the heat being acquired later, and the seminal purgations are from the region of the diaphragm, for the first principle of nature is there, so that the movements
from the pudenda are communicated to the chest, and the smells from the chest are perceived through the respiration. 8. In men, then, and in other kinds, as said before, such deficiency occurs sporadically, but the whole of the mule kind is sterile. The reason has not been rightly given by Empedocles and Democritus, of whom the former expresses himself obscurely, the latter more intelligibly. For they offer their demonstration
in the case of all these animals alike, which unite against their affinities. Democritus says that the genital passages of mules are spoilt in the mother's uterus, because the animals from the first are not produced from parents of the same kind. But we find that, though this is so with other animals, they are, nonetheless, able to generate. Yet, if this were the reason, all others that unite in this manner ought to be barren.
Empedocles assigns, as his reason, that the mixture of the seeds becomes dense, each of the two seminal fluids, out of which it is made being soft. For the hollows in each fit into the densities of the other, and in such cases a hard substance is formed out of soft ones, like bronze mingled with tin. Now, he does not give the correct reason in the case of bronze and tin. We have spoken of them in the problems. Nor to take general ground does he take his
principles from the intelligible. How do the hollows and solids fit into one another to make the mixing? Exempli gratia, in the case of wine and water. This saying is quite beyond us, for how we are to understand the hollows of the wine and water is too far beyond our perception. again when as a matter of fact horse is born of horse ass of ass and mule of horse and ass in two ways according as the parents are stallion and she-ass or jackass and mare why in the last case
does there result something so dense that the offspring is sterile whereas the offspring of male and female horse, male and female ass, is not sterile. And yet the generative fluid of the male and female horse is soft. But both sexes of the horse cross with both sexes of the ass, and the offspring of both crosses are barren, according to Empedocles, because from both is produced something dense, the seeds being soft. If so, the offspring of stallion and
mare ought also to be sterile. If one of them alone united with the ass, it might be said that the cause of the mules being unable to generate was the unlikeness of that one to the generative fluid of the ass. But, as it is, whatever be the character of that generative fluid with which it unites in the ass, such it is also in the animal of its own kind. Then again the argument is intended to apply to both male and female mules alike. But the male
does generate at seven years of age, it is said. It is the female alone that is entirely sterile, and even she is so only because she does not complete the development of the embryo. for a female mule has been known to conceive. Perhaps an abstract proof might appear to be more plausible than those already given. I call it abstract because the more general it is, the further is it removed from the special principles involved. It runs somewhat as follows.
From male and female of the same species there are born in course of nature male and female of the same species as the parents. Exempli gratia, male and female puppies from male and female dog. From parents of different species is born a young one different in species. Thus, if a dog is different from a lion, the offspring of male dog and lioness, or of lion and bitch, will be different from both parents. If this is so, then since 1. Mules are produced
of both sexes, and are not different in species from one another, and 2. A mule is born of horse and ass, and these are different in species from mules, it is impossible that anything should be produced from mules. For 1. Another kind cannot be, because the product of male and female of the same species is also of the same species. And 2. A mule cannot be, because that is the product of horse and ass, which are different in form. And it was laid down, that from parents
different in form is born a different animal. Now, this theory is too general and empty, for all theories not based on the special principles involved are empty. They only appear to be connected with the facts without being so, really. As geometrical arguments must start from geometrical principles, so it is with the others. That which is empty may seem to be something, but is really nothing. Now, the basis of this particular theory is not true.
For many animals of different species are fertile with one another, as was said before. So we must not inquire into questions of natural science in this fashion any more than any other questions. We shall be more likely to find the reason by considering the facts peculiar to the two kinds concerned, horse and ass. In the first place, each of them, if mated with its own kind, bears only one young one. Secondly, the females are not always able to conceive from the male,
wherefore breeders put the horse to the mare again at intervals. Indeed, both the mare is deficient in cataminae, discharging less than any other quadruped, and the she-ass does not admit the impregnation, but ejects the semen with her urine, wherefore men follow flogging her after intercourse. Again, the ass is an animal of cold nature, and so is not wont to be produced in wintry regions, because it cannot bear cold, as in Scythia and the neighboring country, and among the
kilts beyond Iberia, for this country also is cold. For this cause they do not put the jackasses to the females at the equinox, as they do with horses, but about the summer solstice, in order that the ass-fools may be born in a warm season. For the mothers bear at the same season as that in which they are impregnated, the period of gestation in both horse and ass being one year. The animal, then, being, as has been said, of such a cold nature, its semen also must be cold.
A proof of this is that if a horse mount a female already impregnated by an ass, he does not destroy the impregnation of the ass. But if the ass be the second to mount her, he does destroy that of the horse, because of the coldness of his own semen. When, therefore, they unite with each other, the generative elements are preserved by the heat of the one of them, that contributed by the horse being the hotter. For in the ass both the semen of the male
and the material contributed by the female are cold, and those of the horse in both sexes are hotter. Now, when either hot is added to cold, or cold to hot, so as to mix, the result is that the embryo itself arising from these is preserved. And thus these animals are fertile when crossed with one another. But the animal produced by them is no longer fertile, but unable to produce perfect offspring. And in general each of these animals naturally tends towards sterility.
The ass has all the disadvantages already mentioned, and if it should not begin to generate after the first shedding of teeth, it no longer generates at all. So near is the constitution of the ass to being sterile. The horse is much the same. It tends naturally towards sterility, and to make it entirely so, it is only necessary that its generative secretion should become colder. Now this is what happens to it when mixed with the corresponding secretion
of the ass. The ass, in like manner, comes very near generating a sterile animal when mated with its own species. Thus, when the difficulty of a cross, contrary to nature, is added, when two, even in the other case, when united with their own species, they with difficulty produce a single young one, the result of the cross, being still more sterile and contrary to nature will need nothing further to make it sterile, but will be so of necessity. We find
also that the bodies of female mules grow large because the matter which is secreted in other animals to form the catamemia is diverted to growth. But since the period of gestation in such animals is a year. The mule must not only conceive if she is to be fertile, but must also nourish the embryo till birth, and this is impossible if there are no cataminae. But there are none in the mule. The useless part of the nutriment is discharged with the excretion from
the bladder. This is why male mules do not smell to the pudenda of the females, as do the other solid-hoofed ungulates, but only to the evacuation itself, and the rest of the nutriment is used up to increase the size of the body. Hence it is sometimes possible for the female to conceive, as has been known to happen before now, but it is impossible for her to complete the process of nourishing the embryo and bringing it to birth. The male again may sometimes generate
both because the male sex is naturally hotter than the female, and because it does not contribute any material substance to the mixture. The result in such cases is a gynos, that is to say a dwarf mule. Four gyni are produced also from the crossing of horse and ass, when the embryo is diseased in the uterus. The guinos is in fact like the so-called metacoera in swine, for a metacoerum also is a pig injured in the uterus. This may happen to any pig. The origin of human
dwarfs is similar, for these also have their parts and their whole development injured during gestation, and resemble Guinea and Metaquera. End of chapter 8 and end of book 2.
