arteries with hot, eager blood, the penis becomes distended and erect;
also the neck of the _vesicula urinalis_,[5] but when the influx of
blood ceases, and when it is absorbed by the veins, the penis becomes
limp and flabby. Below those nervous bodies is the urethra, and whenever
they swell, it swells also. The penis has four muscles; two shorter ones
springing from the _Cox endix_ and which serve for erection, and on that
account they are called _erectores_; two larger, coming from _sphincters
ani_, which serve to dilate the urethra so as to discharge the semen,
and these are called dilatantes, or wideners. At the end of the penis is
the _glans_, covered with a very thin membrane, by means of which, and
of its nervous substance, it becomes most extremely sensitive, and is
the principal seat of pleasure in copulation. The outer covering of the
_glans_ is called the _preputium_ (foreskin), which the Jews cut off in
circumcision, and it is fastened by the lower part of it to the _glans_.
The penis is also provided with veins, arteries and nerves.

The _testiculi_, stones or testicles (so called because they testify one
to be a man), turn the blood, which is brought to them by the spermatic
arteries into seed. They have two sorts of covering, common and proper;
there are two of the common, which enfold both the testes. The outer
common coat, consists of the _cuticula_, or true skin, and is called the
scrotum, and hangs from the abdomen like a purse; the inner is the
_membrana carnosa_. There are also two proper coats--the outer called
_cliotrodes_, or virginales; the inner _albugidia_; in the outer the
cremaster is inserted. The _epididemes_, or _prostatae_ are fixed to the
upper part of the testes, and from them spring the _vasa deferentia_, or
_ejaculatoria_, which deposit the seed into the _vesicule seminales_
when they come near the neck of the bladder. There are two of these
_vesiculae_, each like a bunch of grapes, which emit the seed into the
urethra in the act of copulation. Near them are the _prostatae_, about