oyster and another a Man—would you not say
this cosmogony could scarcely have misled the
human understanding even in the earliest dawn
of speculative inquiry?Yet such are the
hypotheses to which the desire to philosophise
away that simple proposition of a Divine First
Cause, which every child can comprehend, led
two of the greatest geniuses and profoundest
reasoners of modern times, La Place and La
Marck.* Certainly, the more you examine
those arch phantasmagorists, the philosophers,
who would leave nothing in the universe but
their own delusions, the more your intellectual
pride may be humbled. The wildest phenomena
which have startled you, are not more extravagant
than the grave explanations which
intellectual presumption adventures on the elements
of our own organism and the relations between
the world of matter and the world of ideas."

* See the observations on La Place and La Marck
in the Introduction to Kirby's Bridgewater Treatise.

Here our conversation stopped, for Amy had
now joined us, and, looking up to reply, I saw
the child's innocent face between me and the
furrowed brow of the old man.

MITES.

IF you drive the head of an insect wedgewise
into its thorax you will obtain the shape of a
spider; and if you shove the abdomen into the
other end of the thorax, the result will be
something of the form of a mite. Although, when
young, some of them have only six legs, adult
mites, like all the spider group, have always
eight legs, which are generally composed of
seven more or less distinguishable articulations.
The last articulation, joint, or segment, which
may be called the foot, is furnished with a couple
of movable hooks, folding backward into a
groove or socket adapted to receive them. The
feet of the mites are as various as their instincts.
The feet of the touching mites are dilated; the
feet of the swimming mites are ciliated; the
feet of the running mites are long and slender;
the feet of the weaving mites are bristled; and
the parasitic or near-bread mites are provided
with broad membranes, like discs, stalks, or
suckers, wherewith they stick themselves upon
their victims.

Many kinds of mites are blind. I would
express the fact more correctly by saying they
have no eyes. Fastened upon their food, they
have no need of eyes to guide them when searching
for it. The Hebrew name of these creatures
(cinnim) comes from a root signifying to fix or
establish, and these ticks lodge themselves
firmly in man and in beast, gorging themselves
with blood and juices. Dr. Adam Clark says of
the cinnim, or Acarus sanguisugus, that it is the
fixed or established insect, permitting itself to
be torn to pieces rather than withdraw its hold
and literally burying its head and trunk in the
flesh of its prey. .

The instruments, ordinarily called mandibles,
have in some kinds of mites the form of pincers;
they have in others the shape of lancets; and in
some they resemble stylets. They can pierce
and cut with them. The instruments are
sometimes free, sometimes sheathed, and sometimes
covered. The minuteness of the mites, which
is the very meaning of their English name, has
made the dissection and discrimination of their
internal anatomy extremely difficult, even to
skilful anatomists using the best microscopes.
An eminent French naturalist, not being able to
perceive the gullet, stomach, and intestines of
two species of mites (Trombidium and
Limnochares), having examined these specimens when
these sacks were empty, said he could distinguish
a cylindrical pharynx or opening to the
gullet, with distinct walls containing numerous
muscular fibres to enlarge it and aid suction,
but he could not see either æsophagus, stomach,
or intestines. The food, the blood, and juices
of animals and plants was therefore, he stated,
lodged in mere voids or lacunary spaces,
extending throughout the whole of the body, and
even into the bases of the legs. But more careful
observations have shown the error of these
views. When they are empty, owing to the
thinness, these walls may escape observation,
but when they are full of solid food, says Mr.
Siebold, they may be recognised even in the
smallest species. A good way of preparing
minute animals of this kind for examination
under the microscope is to give them coloured
food. The parts of the mouth and legs which
form the characters of the species, are obtained
by crushing the mites upon a slide, washing
away the exuding matters with a solution of
potash and acetic acid, drying them, and then,
immersing them in Canada balsam. The pincer,
lancet, and stylet mouths, and the dilated,
ciliated, slender, and bristled feet, the eyeless
heads, and adhesive membranes can, when thus
prepared, be preserved and shown distinctly and
beautifully.

Mites are found everywhere. It would be
difficult to say where they are not to be met
with, or to enumerate all the habitats in which
they have been discovered. The study of them
is far from complete, only begun, in fact, and
they have been grouped as those with a
transverse furrow (Acari); and those without a
transverse furrow (Tyroglyphi). Those without
claws and with bristles (Trichodactyli); those
with bristly projections on their body (Psoroptes);
and those with long bristles upon their hind legs
(Sarcoptes). The powder in English cheese
consists of the eggs of Acarus domesticus; and
the powder in the Dutch and Gruyère cheese of
the eggs of Acarus longior. The two-tailed
acarus (A. bicaudatus) occurs upon ostrich
feathers. This fact may be partly explained by
the circumstance that the ostrich feathers of
commerce are not obtained from the wild birds
of the sandy deserts, whose feathers are torn and
ragged, but from the tame birds, kept in
stables for the sake of their feathers. The
Hebrews called the female ostrich the daughter
of vociferation, and the Greeks called the
ostrich the camel bird, and the noise and