e annual history of plant lice and the plants on
which they feed.

FOOTNOTES:

[Footnote 7: "Science from an Easy Chair," Methuen & Co., 1910.]

CHAPTER XIV

PRIMITIVE BELIEFS ABOUT FATHERLESS PROGENY

In the preceding chapter I related the curious and exceptional cases
of "fatherless reproduction" by means of true egg-cells, those cells
of special nature produced in the organs called "ovaries," present in
all but the simplest animals and plants. These egg-cells are usually,
with elaborate sureness and precise mechanism after liberation from
the ovary, fertilised by (that is to say, fused with) the complemental
reproductive cells--the sperm-filaments--produced by other
individuals, the males.

But we must not forget--and, indeed, one should not enter on the
consideration of this subject without a knowledge of the fact--that
vast numbers of animals and plants reproduce themselves "asexually,"
as it is termed, namely, by breaking-off or separating buds, branches,
or other good solid bits of their structure which, when thus
separated, are capable of individual life and growth. Thus plants very
largely multiply, using this method in addition to the sexual method
of egg-cells and sperm-cells. One may take "cuttings" from plants and
rear them, and plants also "cut" or detach such bits themselves, in
the form of runners, of dividing bulbs, of bulbules, and such
reproductive growths seen on the lily, on the viviparous, alpine
grass, and many other plants. Even a bit cut off from the leaf of a
plant (for instance, a begonia) will sprout, root itself, and grow
into a completely formed and healthy individual. Animals, too, such as
polyps or zoophytes, and many beautiful and elaborate worms, multiply
by "fission," dividing into two or more parts, each of which becomes a
complete animal. This process is not seen in any fish, amphibian,
reptile, bird, or mammal, nor in molluscs, nor in insects,
crustaceans, myriapods, and arachnids (spiders and scorpions). It is
almost wholly confined to lower animals (worms and polyps) and to
plants, and hence is often called "vegetative reproduction." The most
remarkable case of its appearance among higher forms is that of the
marine Ascidians, or tunicates--close allies of the true
vertebrates--where reproduction by budding and the formation of
wonderfully elaborate star-like forms produced by budding and the
cohesion of the budded individuals as one composite individual are
well