_The testicles_ are the glandular organs that secrete the spermatozoa, the
essential elements of the seminal fluid. These glands are lodged in the
scrotal sack, situated between the two thighs.

Lying along the superior border of the testicle is a mass of ducts, the
_epididymis_. The _vas deferens_ is the canal or duct that passes
from the epididymis to the region of the bladder and terminates near its
neck by emptying into the seminal vesicles.

_The seminal vesicles_ are two membranous pouches situated just above the
bladder. They act as receptacles for the seminal fluid. Two short ducts,
the _ejaculatory_, carry the seminal fluid from the seminal vesicles to the
urethra.

_The prostate gland_ is situated near the origin of the urethra. _Cowper's
glands_ lie along the course of the urethra and near the origin of the
penis. These glands empty their secretions into the urethra and dilute the
seminal fluid.

_The penis_ is the male organ of copulation. It originates at the arch of
the ischium and extends forward between the thighs. It may be divided into
fixed and free portions. The free portion is lodged in the prepuce or
sheath, but at the time of erection protrudes from it.

STERILITY, IMPOTENCY.--Fecundation does not always follow intercourse of
the male and female. Impotency in the male and sterility in the female
frequently occur.

_The causes_ are quite varied. A normal copulation may be impossible