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History of Animals   


in each case.
The males of oviparous animals, whether biped or quadruped, are
in all cases furnished with testicles close to the loin underneath the
midriff. With some animals the organ is whitish, in others somewhat of
a sallow hue; in all cases it is entirely enveloped with minute and
delicate veins. From each of the two testicles extends a duct, and, as
in the case of fishes, the two ducts coalesce into one above the
outlet of the residuum. This constitutes the penis, which organ in the
case of small ovipara is inconspicuous; but in the case of the
larger ovipara, as in the goose and the like, the organ becomes
quite visible just after copulation.
The ducts in the case of fishes and in biped and quadruped
ovipara are attached to the loin under the stomach and the gut, in
betwixt them and the great vein, from which ducts or blood-vessels
extend, one to each of the two testicles. And just as with fishes
the male sperm is found in the seminal ducts, and the ducts become
plainly visible at the rutting season and in some instances become
invisible after the season is passed, so also is it with the testicles
of birds; before the breeding season the organ is small in some
birds and quite invisible in others, but during the season the organ
in all cases is greatly enlarged. This phenomenon is remarkably
illustrated in the ring-dove and the partridge, so much so that some
people are actually of opinion that these birds are devoid of the
organ in the winter-time.
Of male animals that have their testicles placed frontwards, some
have them inside, close to the belly, as the dolphin; some have them
outside, exposed to view, close to the lower extremity of the belly.
These animals resemble one another thus far in respect to this
organ; but they differ from one another in this fact, that some of
them have their testicles situated separately by themselves, while
others, which have the organ situated externally, have them
enveloped in what is termed the scrotum.
Again, in all viviparous animals furnished with feet the
following properties are observed in the testicles themselves. From
the aorta there extend vein-like ducts to the head of each of the
testicles, and another two from the kidneys; these two from the
kidneys are supplied with blood, while the two from the aorta are
devoid of it. From the head of the testicle alongside of the
testicle itself is a duct, thicker and more sinewy than the other just
alluded to-a duct that bends back again at the end of the testicle
to its head; and from the head of each of the two testicles the two
ducts extend until they coalesce in front at the penis. The duct
that bends back again and that which is in contact with the testicle
are enveloped in one and the same membrane, so that, until you draw
aside the membrane, they present all the appearance of being a
single undifferentiated duct. Further, the duct in contact with the
testicle has its moist content qualified by blood, but to a
comparatively less extent than in the case of the ducts higher up
which are connected with the aorta; in the ducts that bend back
towards the tube of the penis, the liquid is white-coloured. There
also runs a duct from the bladder, opening into the upper part of
the canal, around which lies, sheathwise, what is called the 'penis'.
All these descriptive particulars may be regarded by the light of
the accompanying diagram; wherein the letter A marks the
starting-point of the ducts that extend from the aorta; the letters KK
mark the heads of the testicles and the ducts descending thereunto;
the ducts extending from these along the testicles are marked MM; the
ducts turning back, in which is the white fluid, are marked BB; the
penis D; the bladder E; and the testicles XX.
(By the way, when the testicles are cut off or removed, the ducts
draw upwards by contraction. Moreover, when male animals are young,
their owner sometimes destroys the organ in them by attrition;
sometimes they castrate them at a later period. And I may here add,
that a bull has been known to serve a cow immediately after

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