incipal organs of reproduction, we may obtain a more definite
idea of the relation of the several organs of each class by a connected
review of the anatomy of the parts.

Male Organs.--As previously stated, the external organs of generation
in the male are the _penis_ and the _testicles_, the latter being
contained in a pouch called the _scrotum_. The penis is the organ of
urination as well as copulation. Its structure is cellular, and it
contains a vast number of minute coils of blood-vessels which become
turgid with blood under the influence of sexual excitement, producing
distention and erection of the organ. A canal passes through its entire
length, called the _urethra_, which conveys both the urine and the
seminal fluid. The organ is protected by a loose covering of integument
which folds over the end. This fold is called the _foreskin_ or
_prepuce_.

The fluid formed by each testicle is conveyed by the _vas deferens_,
a curved tube about two feet in length, to the base of the bladder.
Here the vas deferens joins with another duct which communicates with
an elongated pouch, the _vesicula seminalis_, which lies close upon
the under side of the bladder. The single tube thus formed, the
_ejaculatory duct_, conveys the seminal fluid to the urethra, from
which it is discharged.

As the production of seminal fluid is more or less constant in man and
some animals, while its discharge is intermittent, the vesiculae
seminales serve as reservoirs for the fluid, preserving it until
required, or allowing it to undergo absorption. Some claim that the
zoosperms are matured in these organs. They always contain seminal
fluid after the age of puberty. During coition, their contents are
forcibly expelled by a spasmodic contraction of the muscles which
surround them and the ducts leading from them.

The Prostate Gland.--Surrounding the ejaculatory ducts and their
openings into the urethra at the base of the bladder is the _prostate
gland_, which produces a peculiar secretion which forms a considerable
portion of the seminal fluid, being mingled with the secretion of the
testes during its ejaculation. This gland sometimes becomes the seat
of somewhat serious disease. In old age it usually becomes somewhat
indurated, and often to such an extent as to seriously affect the health
and comfort of the individual by interference with urination and by
occasioning pain.

Anterior to this organ, in the urethra, is a curious little pouch,