Final
Cause of Spermatic Organs
With regard to the
difference of the spermatic organs in males, if we are to
investigate
the causes of their existence, we must first grasp the final cause
of the testes. Now if nature makes everything either because it is
necessary
or because it is better so, this part also must be for one of these
two reasons. But that it is not necessary for generation is plain
[because]
neither serpents have testes nor have fish... It remains then that it
must
be because it is somehow better so... [Those animals] which have not
testes
but only ducts... are all quicker in accomplishing copulation. But
those
which are to be more temperate... have their ducts twisted to prevent
their
desire being too violent and hasty. It is for this that the testes are
contrived; for they make the movement of the spermatic secretion
steadier....
Serpents copulate
twining
round one another, and ... have neither testes nor penis, the latter
because
they have no legs, the former because of their length, but they have
ducts
like fish; for on account of their extreme length the seminal fluid
would
take too long in its passage and be cooled if it were further delayed
by
testes. (This happens also if the penis is large; such men are less
fertile
than when it is smaller because semen, if cold, is not generative, and
that which is carried too far is cooled.) So much the reason why some
animals
have testes and others not.
- Aristotle, "Generation of Animals" (4th cent. BCE)