during
waking hours only through strong stimulation of the activity of the
testes, accompanied by liberation of spermatozoa and of the other
elements of the vital fluid. Let us not forget in this connection, the
statement made above: that the testis produces two forms of secretion,
the internal secretion and the external secretion, the internal
secretion being absorbed, produces those male characteristics which we
group together under virility, while the external secretion is used
for procreation. Spermatozoa do not make any part of the internal
secretion. One reason for this must be evident, i.e., that being
cellular elements, they could not pass through the vessel walls and be
absorbed into the blood current, and if they could, by some special
adaptation, get into the blood current, there is no conceivable action
which they could perform in the body. We must then look upon the
internal secretion as composed of the liquid elements of the
testicular secretion.

So far as physiologists know at present, the external secretion
differs from the internal secretion only in possessing spermatozoa.
When we say that the testes form their external secretion under sexual
excitement only, we simply mean that they liberate or release
spermatozoa under sexual excitement. The spermatozoa must be looked
upon as the fertilizing element of the semen, while the liquid portion
of the semen probably contains that mysterious element which, absorbed
into the body, produces virility and which, passed out with the
spermatozoa, may have an important role to perform in the fertilizing
function.

If the adolescent young man is leading a continent life, we may assume
that from time to time he is subjected to conditions which serve as
strong sexual stimuli, arousing in him a definite desire for sexual
intercourse; but leading a continent life, he curbs his desire and
fixes his thoughts upon other subjects. In this way, though the sexual
excitement is brought quickly under abeyance, we can rest assured that
a certain number of spermatozoa have been released from the testes;
and that the other secretions have been increased in volume. The
excitement may be sufficient even to cause an erection, and produce a
few drops of the secretion of Cowper's glands. The spermatozoa,
together with a small amount of the liquid secretion, will make their
way gradually along the vasa deferentia and collect in the ampullae.
The bulk of the liquid secretion, however