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On The Generation Of Animals   

has been often stated of fish. With animals internally viviparous
the embryo becomes egg-like in a certain sense after its original
formation, for the liquid is contained in a fine membrane, just as
if we should take away the shell of the egg, wherefore they call the
abortion of an embryo at that stage an 'efflux'.

Those insects which generate at all generate a scolex, and those
which come into being spontaneously and not from copulation do so at
first from a formation this nature. I say that the former generate a
scolex, for we must put down caterpillars also and the product of
spiders as a sort of scolex. And yet some even of these and many of
the others may be thought to resemble eggs because of their round
shape, but we must not judge by shapes nor yet by softness and
hardness (for what is produced by some is hard), but by the fact
that the whole of them is changed into the body of the creature and
the animal is not developed from a part of them. All these products
that are of the nature of a scolex, after progressing and acquiring
their full size, become a sort of egg, for the husk about them hardens
and they are motionless during this period. This is plain in the
scolex of bees and wasps and in caterpillars. The reason of this is
that their nature, because of its imperfection, oviposits as it were
before the right time, as if the scolex, while still growing in
size, were a soft egg. Similar to this is also what happens with all
other insects which come into being without copulation in wool and
other such materials and in water. For all of them after the scolex
stage become immovable and their integument dries round them, and
after this the latter bursts and there comes forth as from an egg an
animal perfected in its second metamorphosis, most of those which
are not aquatic being winged.

Another point is quite natural, which may wondered at by many.
Caterpillars at first take nourishment, but after this stage do so
no longer, but what is called by some the chrysalis is motionless. The
same applies to the scolex of wasps and bees, but after this comes
into being the so-called nymph.... and have nothing of the kind. For
an egg is also of such a nature that when it has reached perfection it
grows no more in size, but at first it grows and receives
nourishment until it is differentiated and becomes a perfect egg.
Sometimes the scolex contains in itself the material from which it
is nourished and obtains such an addition to its size, e.g. in bees
and wasps; sometimes it gets its nourishment from outside itself, as
caterpillars and some others.

It has thus been stated why such animals go through a double
development and for what reason they become immovable again after
moving. And some of them come into being by copulation, like birds and
vivipara and most fishes, others spontaneously, like some plants.


There is much difficulty about the generation of bees. If it is
really true that in the case of some fishes there is such a method
of generation that they produce eggs without copulation, this may well
happen also with bees, to judge from appearances. For they must (1)
either bring the young brood from elsewhere, as some say, and if so
the young must either be spontaneously generated or produced by some
other animal, or (2) they must generate them themselves, or (3) they
must bring some and generate others, for this also is maintained by
some, who say that they bring the young of the drones only. Again,
if they generate them it must be either with or without copulation; if
the former, then either (1) each kind must generate its own kind, or
(2) some one kind must generate the others, or (3) one kind must unite
with another for the purpose (I mean for instance (1) that bees may
be generated from the union of bees, drones from that of drones, and

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