tion of plants are more or less parasitic, they gain, thereby in
interest to the botanist, and many of them are eagerly sought as the
choicest ornaments of our conservatories. Not so with their zooelogical
confreres. All that is repulsive and uncanny is associated with them,
and those who study them, though perhaps among the keenest intellects
and most industrious observers, speak of them without the limits of
their own circle in subdued whispers or under a protest, and their works
fall under the eyes of the scantiest few. But the study of animal
parasites has opened up new fields of research, all bearing most
intimately on those two questions that ever incite the naturalist to the
most laborious and untiring diligence--what is life and its origin? The
subjects of the alternation of generations, or parthenogenesis, of
embryology and biology, owe their great advance, in large degree, to the
study of such animals as are parasitic, and the question whether the
origin of species be due to creation by the action of secondary laws or
not, will be largely met and answered by the study of the varied
metamorphoses and modes of growth, the peculiar modification of organs
that adapt them to their strange modes of life, and the consequent
variation in specific characters so remarkably characteristic of those
animals living parasitically upon others.[6]

With these considerations in view surely a serious, thoughtful, and
thorough study of the louse, in all its varieties and species, is
neither belittling nor degrading, nor a waste of time. We venture to
say, moreover, that more light will be thrown on the classification and
morphology of insects by the study of the parasitic species, and other
degraded, wingless forms that do not always live parasitically,
especially of their embryology and changes after leaving the egg, than
by years of study of the more highly developed insects alone. Among
Hymenoptera the study of the minute Ichueumons, such as the
Proctotrupids and Chalcids, especially the egg-parasites; among moths
the study of the wingless canker-worm moth and Orgyla; among Diptera the
flea, bee louse, sheep tick, bat tick, and other wingless flies; among
Coleoptera, the Meloe, and singular Stylops and Xenos; among Neuroptera,
the snow insect, Boreus, the Podura (Fig. 109) and Lepisma, and
especially the hemipterous lice, will throw a flood of light on these
prime subjects in philosophical entomology.

[Illustration: 109. Pod