Aristotle

by Various Works [lit]

  To return to testacea, some of them are formed spontaneously, some

  emit a sort of generative substance from themselves, but these also

  often come into being from a spontaneous formation. To understand this

  we must grasp the different methods of generation in plants; some of

  these are produced from seed, some from slips, planted out, some by

  budding off alongside, as the class of onions. In the last way

  produced mussels, for smaller ones are always growing off alongside

  the original, but the whelks, the purple-fish, and those which are

  said to 'spawn' emit masses of a liquid slime as if originated by

  something of a seminal nature. We must not, however, consider that

  anything of the sort is real semen, but that these creatures

  participate in the resemblance to plants in the manner stated above.

  Hence when once one such creature has been produced, then is

  produced a number of them. For all these creatures are liable to be

  even spontaneously generated, and so to be formed still more

  plentifully in proportion if some are already existing. For it is

  natural that each should have some superfluous residue attached to

  it from the original, and from this buds off each of the creatures

  growing alongside of it. Again, since the nutriment and its residue

  possess a like power, it is likely that the product of those

  testacea which 'spawn' should resemble the original formation, and

  so it is natural that a new animal of the same kind should come into

  being from this also.

  All those which do not bud off or 'spawn' are spontaneously

  generated. Now all things formed in this way, whether in earth or

  water, manifestly come into being in connexion with putrefaction and

  an admixture of rain-water. For as the sweet is separated off into the

  matter which is forming, the residue of the mixture takes such a form.

  Nothing comes into being by putrefying, but by concocting;

  putrefaction and the thing putrefied is only a residue of that which

  is concocted. For nothing comes into being out of the whole of

  anything, any more than in the products of art; if it did art would

  have nothing to do, but as it is in the one case art removes the

  useless material, in the other Nature does so. Animals and plants come

  into being in earth and in liquid because there is water in earth, and

  air in water, and in all air is vital heat so that in a sense all

  things are full of soul. Therefore living things form quickly whenever

  this air and vital heat are enclosed in anything. When they are so

  enclosed, the corporeal liquids being heated, there arises as it

  were a frothy bubble. Whether what is forming is to be more or less

  honourable in kind depends on the embracing of the psychical

  principle; this again depends on the medium in which the generation

  takes place and the material which is included. Now in the sea the

  earthy matter is present in large quantities, and consequently the

  testaceous animals are formed from a concretion of this kind, the

  earthy matter hardening round them and solidifying in the same

  manner as bones and horns (for these cannot be melted by fire),

  and the matter (or body) which contains the life being included

  within it.

  The class of snails is the only class of such creatures that has

  been seen uniting, but it has never yet been sufficiently observed

  whether their generation is the result of the union or not.

  It may be asked, if we wish to follow the right line of

  investigation, what it is in such animals the formation of which

  corresponds to the material principle. For in the females this is a

  residual secretion of the animal, potentially such as that from

  which it came, by imparting motion to which the principle derived from

  the male perfects the animal. But here what must be said to correspond

  to this, and whence comes or what is the moving principle which

  corresponds to the male? We must understand that even in animals which

  generate it is from the incoming nourishment that the heat in the

  animal makes the residue, the beginning of the conception, by

  secretion and concoction. The like is the case also in plants,

  except that in these (and also in some animals) there is no

  further need of the male principle, because they have it mingled

  with the female principle within themselves, whereas the residual

  secretion in most animals does need it. The nourishment again of

  some is earth and water, of others the more complicated combinations

  of these, so that what the heat in animals produces from their

  nutriment, this does the heat of the warm season in the environment

  put together and combine by concoction out of the sea-water on the

  earth. And the portion of the psychical principle which is either

  included along with it or separated off in the air makes an embryo and

  puts motion into it. Now in plants which are spontaneously generated

  the method of formation is uniform; they arise from a part of

  something, and while some of it is the starting-point of the plant,

  some is the first nourishment of the young shoots.... Other animals

  are produced in the form of a scolex, not only those bloodless animals

  which are not generated from parents but even some sanguinea, as a

  kind of mullet and some other river fishes and also the eel kind.

  For all of these, though they have but little blood by nature, are

  nevertheless sanguinea, and have a heart with blood in it as the

  origin of the parts; and the so-called 'entrails of earth', in which

  comes into being the body of the eel, have the nature of a scolex.

  Hence one might suppose, in connexion with the origin of men and

  quadrupeds, that, if ever they were really 'earth-born' as some say,

  they came into being in one of two ways; that either it was by the

  formation of a scolex at first or else it was out of eggs. For

  either they must have had in themselves the nutriment for growth (and

  such a conception is a scolex) or they must have got it from

  elsewhere, and that either from the mother or from part of the

  conception. If then the former is impossible (I mean that nourishment

  should flow to them from the earth as it does in animals from the

  mother), then they must have got it from some part of the conception,

  and such generation we say is from an egg.

  It is plain then that, if there really was any such beginning of the

  generation of all animals, it is reasonable to suppose to have been

  one of these two, scolex or egg. But it is less reasonable to

  suppose that it was from eggs, for we do not see such generation

  occurring with any animal, but we do see the other both in the

  sanguinea above mentioned and in the bloodless animals. Such are

  some of the insects and such are the testacea which we are discussing;

  for they do not develop out of a part of something (as do animals

  from eggs), and they grow like a scolex. For the scolex grows towards

  the upper part and the first principle, since in the lower part is the

  nourishment for the upper. And this resembles the development of

  animals from eggs, except that these latter consume the whol
e egg,

  whereas in the scolex, when the upper part has grown by taking up into

  itself part of the substance in the lower part, the lower part is then

  differentiated out of the rest. The reason is that in later life

  also the nourishment is absorbed by all animals in the part below

  the hypozoma.

  That the scolex grows in this way is plain in the case of bees and

  the like, for at first the lower part is large in them and the upper

  is smaller. The details of growth in the testacea are similar. This is

  plain in the whorls of the turbinata, for always as the animal grows

  the whorls become larger towards the front and what is called the head

  of the creature.

  We have now pretty well described the manner of the development of

  these and the other spontaneously generated animals. That all the

  testacea are formed spontaneously is clear from such facts as these.

  They come into being on the side of boats when the frothy mud

  putrefies. In many places where previously nothing of the kind

  existed, the so-called limnostrea, a kind of oyster, have come into

  being when the spot turned muddy through want of water; thus when a

  naval armament cast anchor at Rhodes a number of clay vessels were

  thrown out into the sea, and after some time, when mud had collected

  round them, oysters used to be found in them. Here is another proof

  that such animals do not emit any generative substance from

  themselves; when certain Chians carried some live oysters over from

  Pyrrha in Lesbos and placed them in narrow straits of the sea where

  tides clash, they became no more numerous as time passed, but

  increased greatly in size. The so-called eggs contribute to generation

  but are only a condition, like fat in the sanguinea, and therefore the

  oysters are savoury at these periods. A proof that this substance is

  not really eggs is the fact that such 'eggs' are always found in

  some testacea, as in pinnae, whelks, and purple-fish; only they are

  sometimes larger and sometimes smaller; in others as pectens, mussels,

  and the so-called limnostrea, they are not always present but only

  in the spring; as the season advances they dwindle and at last

  disappear altogether; the reason being that the spring is favourable

  to their being in good condition. In others again, as the ascidians,

  nothing of the sort is visible. (The details concerning these last,

  and the places in which they come into being, must be learnt from

  the Enquiry.)

  Book IV

  1

  WE have thus spoken of the generation of animals both generally

  and separately in all the different classes. But, since male and

  female are distinct in the most perfect of them, and since we say that

  the sexes are first principles of all living things whether animals or

  plants, only in some of them the sexes are separated and in others

  not, therefore we must speak first of the origin of the sexes in the

  latter. For while the animal is still imperfect in its kind the

  distinction is already made between male and female.

  It is disputed, however, whether the embryo is male or female, as

  the case may be, even before the distinction is plain to our senses,

  and further whether it is thus differentiated within the mother or

  even earlier. It is said by some, as by Anaxagoras and other of the

  physicists, that this antithesis exists from the beginning in the

  germs or seeds; for the germ, they say, comes from the male while

  the female only provides the place in which it is to be developed, and

  the male is from the right, the female from the left testis, and so

  also that the male embryo is in the right of the uterus, the female in

  the left. Others, as Empedocles, say that the differentiation takes

  place in the uterus; for he says that if the uterus is hot or cold

  what enters it becomes male or female, the cause of the heat or cold

  being the flow of the catamenia, according as it is colder or

  hotter, more 'antique' or more 'recent'. Democritus of Abdera also

  says that the differentiation of sex takes place within the mother;

  that however it is not because of heat and cold that one embryo

  becomes female and another male, but that it depends on the question

  which parent it is whose semen prevails,- not the whole of the

  semen, but that which has come from the part by which male and

  female differ from one another. This is a better theory, for certainly

  Empedocles has made a rather light-hearted assumption in thinking that

  the difference between them is due only to cold and heat, when he

  saw that there was a great difference in the whole of the sexual

  parts, the difference in fact between the male pudenda and the uterus.

  For suppose two animals already moulded in embryo, the one having

  all the parts of the female, the other those of the male; suppose them

  then to be put into the uterus as into an oven, the former when the

  oven is hot, the latter when it is cold; then on the view of

  Empedocles that which has no uterus will be female and that which

  has will be male. But this is impossible. Thus the theory of

  Democritus would be the better of the two, at least as far as this

  goes, for he seeks for the origin of this difference and tries to

  set it forth; whether he does so well or not is another question.

  Again, if heat and cold were the cause of the difference of the

  parts, this ought to have been stated by those who maintain the view

  of Empedocles; for to explain the origin of male and female is

  practically the same thing as to explain this, which is the manifest

  difference between them. And it is no small matter, starting from

  temperature as a principle, to collect the cause of the origin of

  these parts, as if it were a necessary consequence for this part which

  they call the uterus to be formed in the embryo under the influence of

  cold but not under that of heat. The same applies also to the parts

  which serve for intercourse, since these also differ in the way stated

  previously.

  Moreover male and female twins are often found together in the

  same part of the uterus; this we have observed sufficiently by

  dissection in all the vivipara, both land animals and fish. Now if

  Empedocles had not seen this it was only natural for him to fall

  into error in assigning this cause of his; but if he had seen it it is

  strange that he should still think the heat or cold of the uterus to

  be the cause, since on his theory both these twins would have become

  either male or female, but as it is we do not see this to be the fact.

  Again he says that the parts of the embryo are 'sundered', some

  being in the male and some in the female parent, which is why they

  desire intercourse with one another. If so it is necessary that the

  sexual parts like the rest should be separated from one another,

  already existing as masses of a certain size, and that they should

  come into being in the embryo on account of uniting with one

  another, not on account of cooling or heating of the semen. But

  perhaps it would take too long to discuss thoroughly such a cause as

  this which is stated
by Empedocles, for its whole character seems to

  be fanciful. If, however, the facts about semen are such as we have

  actually stated, if it does not come from the whole of the body of the

  male parent and if the secretion of the male does not give any

  material at all to the embryo, then we must make a stand against

  both Empedocles and Democritus and any one else who argues on the same

  lines. For then it is not possible that the body of the embryo

  should exist 'sundered', part in the female parent and part in the

  male, as Empedocles says in the words: 'But the nature of the limbs

  hath been sundered, part in the man's...'; nor yet that a whole embryo

  is drawn off from each parent and the combination of the two becomes

  male or female according as one part prevails over another.

  And, to take a more general view, though it is better to say that

  the one part makes the embryo female by prevailing through some

  superiority than to assign nothing but heat as the cause without any

  reflection, yet, as the form of the pudendum also varies along with

  the uterus from that of the father, we need an explanation of the fact

  that both these parts go along with each other. If it is because

  they are near each other, then each of the other parts also ought to

  go with them, for one of the prevailing parts is always near another

  part where the struggle is not yet decided; thus the offspring would

  be not only female or male but also like its mother or father

  respectively in all other details.

  Besides, it is absurd to suppose that these parts should come into

  being as something isolated, without the body as a whole having

  changed along with them. Take first and foremost the blood-vessels,

  round which the whole mass of the flesh lies as round a framework.

  It is not reasonable that these should become of a certain quality

  because of the uterus, but rather that the uterus should do so on

  account of them. For though it is true that each is a receptacle of

  blood of some kind, still the system of the vessels is prior to the

  other; the moving principle must needs always be prior to that which

  it moves, and it is because it is itself of a certain quality that