certainly most extensive. It would be impossible to lay it all before
you, and the most I can do, or need do to-night, is to take up the
principal points and put them before you with such prominence as may
subserve the purposes of our present argument.

The method of the perpetuation of organic beings is of two kinds,--the
asexual and the sexual. In the first the perpetuation takes place from
and by a particular act of an individual organism, which sometimes may
not be classed as belonging to any sex at all. In the second case, it
is in consequence of the mutual action and interaction of certain
portions of the organisms of usually two distinct individuals,--the
male and the female. The cases of asexual perpetuation are by no means
so common as the cases of sexual perpetuation; and they are by no means
so common in the animal as in the vegetable world. You are all
probably familiar with the fact, as a matter of experience, that you
can propagate plants by means of what are called "cuttings;" for
example, that by taking a cutting from a geranium plant, and rearing it
properly, by supplying it with light and warmth and nourishment from
the earth, it grows up and takes the form of its parent, having all the
properties and peculiarities of the original plant.

Sometimes this process, which the gardener performs artificially, takes
place naturally; that is to say, a little bulb, or portion of the
plant, detaches itself, drops off, and becomes capable of growing as a
separate thing. That is the case with many bulbous plants, which throw
off in this way secondary bulbs, which are lodged in the ground and
become developed into plants. This is an asexual process, and from it
results the repetition or reproduction of the form of the original
being from which the bulb proceeds.