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On The Generation Of Animals   

perfect only as the embryo of a plant, but imperfect as that of an
animal. If, then, there had been no male sex in the class of birds,
the egg would have been produced as it is in some fishes, if indeed
there is any kind of fish of such a nature as to generate without a
male; but it has been said of them before that this has not yet been
satisfactorily observed. But as it is both sexes exist in all birds,
so that, considered as a plant, the egg is perfect, but in so far as
it is not a plant it is not perfect, nor does anything else result
from it; for neither has it come into being simply like a real plant
nor from copulation like an animal. Eggs, however, produced from
copulation but already separated into white and yolk take after the
first cock; for they already contain both principles, which is why
they do not change again after the second impregnation.


The young are produced in the same way also by the cephalopoda, e.g.
sepias and the like, and by the crustacea, e.g. carabi and their
kindred, for these also lay eggs in consequence of copulation, and the
male has often been seen uniting with the female. Therefore those
who say that all fish are female and lay eggs without copulation are
plainly speaking unscientifically from this point of view also. For it
is a wonderful thing to suppose that the former animals lay eggs in
consequence of copulation and that fish do not; if again they were
unaware of this, it is a sign of ignorance. The union of all these
creatures lasts a considerable time, as in insects, and naturally
so, for they are bloodless and therefore of a cold nature.

In the sepias and calamaries or squids the eggs appear to be two,
because the uterus is divided and appears double, but that of the
poulps appears to be single. The reason is that the shape of the
uterus in the poulp is round in form and spherical, the cleavage being
obscure when it is filled with eggs. The uterus of the carabi is
also bifid. All these animals also lay an imperfect egg for the same
reason as fishes. In the carabi and their like the females produce
their eggs so as to keep them attached to themselves, which is why the
side-flaps of the females are larger than those of the males, to
protect the eggs; the cephalopoda lay them away from themselves. The
males of the cephalopoda sprinkle their milt over the females, as
the male fish do over the eggs, and it becomes a sticky and
glutinous mass, but in the carabi and their like nothing of the sort
has been seen or can be naturally expected, for the egg is under the
female and is hard-shelled. Both these eggs and those of the
cephalopoda grow after deposition like those of fishes.

The sepia while developing is attached to the egg by its front part,
for here alone is it possible, because this animal alone has its front
and back pointing in the same direction. For the position and attitude
of the young while developing you must look at the Enquiries.


We have now spoken of the generation of other animals, those that
walk, fly, and swim; it remains to speak of insects and testacea
according to the plan laid down. Let us begin with the insects. It was
observed previously that some of these are generated by copulation,
others spontaneously, and besides this that they produce a scolex, and
why this is so. For pretty much all creatures seem in a certain way to
produce a scolex first, since the most imperfect embryo is of such a
nature; and in all animals, even the viviparous and those that lay a
perfect egg, the first embryo grows in size while still
undifferentiated into parts; now such is the nature of the scolex.
After this stage some of the ovipara produce the egg in a perfect
condition, others in an imperfect, but it is perfected outside as

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