phenomena that people love to conceal behind the mystic veil of
supernatural power. We shall soon see, however, that it is a purely
mechanical process, and can be reduced to familiar physiological
functions. Moreover, this process of conception is of the same type,
and is effected by the same organs, in man as in all the other
mammals. The pairing of the male and female has in both cases for its
main purpose the introduction of the ripe matter of the male seed or
sperm into the female body, in the sexual canals of which it
encounters the ovum. Conception then ensues by the blending of the
two.

We must observe, first, that this important process is by no means so
widely distributed in the animal and plant world as is commonly
supposed. There is a very large number of lower organisms which
propagate unsexually, or by monogamy; these are especially the sexless
monera (chromacea, bacteria, etc.) but also many other protists, such
as the amoebae, foraminifera, radiolaria, myxomycetae, etc. In these
the multiplication of individuals takes place by unsexual
reproduction, which takes the form of cleavage, budding, or
spore-formation. The copulation of two coalescing cells, which in
these cases often precedes the reproduction, cannot be regarded as a
sexual act unless the two copulating plastids differ in size or
structure. On the other hand, sexual reproduction is the general rule
with all the higher organisms, both animal and plant; very rarely do
we find asexual reproduction among them. There are, in particular, no
cases of parthenogenesis (virginal conception) among the vertebrates.

Sexual reproduction offers an infinite variety of interesting forms in
the different classes of animals and plants, especially as regards the
mode of conception, and the conveyance of the spermatozoon to the