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
castration, and actually to impregnate her.)