These organs in
the female are in all cases internal; in the male they present
numerous diversities.
In the blooded animals some males are altogether devoid of
testicles, and some have the organ but situated internally; and of
those males that have the organ internally situated, some have it
close to the loin in the neighbourhood of the kidney and others close
to the belly. Other males have the organ situated externally. In the
case of these last, the penis is in some cases attached to the belly,
whilst in others it is loosely suspended, as is the case also with the
testicles; and, in the cases where the penis is attached to the belly,
the attachment varies accordingly as the animal is emprosthuretic or
opisthuretic.
No fish is furnished with testicles, nor any other creature that has
gills, nor any serpent whatever: nor, in short, any animal devoid of
feet, save such only as are viviparous within themselves. Birds are
furnished with testicles, but these are internally situated, close to
the loin. The case is similar with oviparous quadrupeds, such as the
lizard, the tortoise and the crocodile; and among the viviparous
animals this peculiarity is found in the hedgehog. Others among those
creatures that have the organ internally situated have it close to the
belly, as is the case with the dolphin amongst animals devoid of feet,
and with the elephant among viviparous quadrupeds. In other cases
these organs are externally conspicuous.
We have already alluded to the diversities observed in the
attachment of these organs to the belly and the adjacent region; in
other words, we have stated that in some cases the testicles are
tightly fastened back, as in the pig and its allies, and that in
others they are freely suspended, as in man.
Fishes, then, are devoid of testicles, as has been stated, and
serpents also. They are furnished, however, with two ducts connected
with the midriff and running on to either side of the backbone,
coalescing into a single duct above the outlet of the residuum, and by
'above' the outlet I mean the region near to the spine. These ducts in
the rutting season get filled with the genital fluid, and, if the
ducts be squeezed, the sperm oozes out white in colour. As to the
differences observed in male fishes of diverse species, the reader
should consult my treatise on Anatomy, and the subject will be
hereafter more fully discussed when we describe the specific character
in each case.
{BK3|CH1 ^paragraph 5}
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