splendid objects. From amongst these the observer may select the peacock
or coloured copper ore, green crystallized ditto, lead ore,
crystallized ditto, crystals of lead, small grained marcasites, coloured
mundic, cinnabar, native sulphur, needle and other antimony, moss
copper, &c. A mixture of small pieces of ores, &c. of different kinds,
produces a pleasing effect. Sands in general exhibit something not
discoverable with the naked eye. Sand from the sea-shore is often
intermixed with minute shells, particularly that from Rimini, in Italy.
Mr. Walker has published a specimen of the small microscopic shells
which are found on our own coast. From this work we learn, that there
are shell-fish as small as the minutest insects, and possessed of
beauties of which we can form no conception till we have seen them. Mr.
Walker’s work is entitled, “A Collection of the minute and rare Shells
lately discovered in the Sand on the Sea-shore near Sandwich.”[147]
There is a sand from Africa full of small garnets. The ketton, or
kettering stone, is a pleasing object; when examined by the microscope,
we find the grain of it very different from that of other stones, being
composed of innumerable minute balls, which barely touch each other, and
yet form a substance much harder than free-stone; the grains are, in
general, so firmly united together at the points of contact, that it is
hardly possible to separate them without breaking one or both of the
grains. See Hooke’s Micrographia.
[147] This publication will be more particularly noticed in the
ensuing chapter. EDIT.
Insects of all kinds, both foreign and domestic, are pleasing objects;
but as the foreign ones are not so easily met with, I shall mention but
a few of them, confining myself principally to those of this country.
Among the exotic insects, none appear more beautiful in the microscope
than the curculio imperialis, Brazil or diamond beetle; the buprestis
ignita, or large beetle from China; the meloe vesicatorius, Linn. the
cantharis or Spanish fly of the shops; several species of locusts,
grasshoppers, &c. Among the English beetles, we may reckon the
scarabæus auratus or rose chaffer, scarabæus nobilis, scarabæus
horticola, silpha aquatica, cassida nobilis and nebulosa. Coccinella or
lady-cow; of these there are great varieties both in size and colour,
some red and black, others black and red, and some yellow and black.
Chrysomela graminis, chrysomela fastuosa, chrysomela nitidula,
chrysomela sericea, chrysomela melanopa, chrysomela asparagi, see Plate
XX. Fig. 2. Curculio frumentarius, lapathi, betula, nucum, scrophularia,
argenteus, a beautiful little insect resembling the diamond beetle, but
in miniature; curculio albinus, very beautiful, but scarce in this
country. Leptura aquatica, these are of various colours, as blue,
purple, bronze, and crimson. Arcuata arietis, very common, and is often
called the wasp beetle. Cicindela campestris, on dry banks. Carabus
nitens, found in Yorkshire, a beautiful insect; many small carabi.
Gryllus, gryllo-talpa or mole cricket, this insect, and the
grasshoppers, are many of them too large to be observed at one view, but
the head, fore and hind feet, elytra, &c. viewed separately, are fine
objects. Cicada sanguinolenta, nervosa, interrupta, notonecta striata,
minutissima, head and claws of the nepa cinerea or water-scorpion, and
the whole variety of cimices or field bugs. The wings of butterflies and
moths; the chrysalis of the common white butterfly is extremely fine.
I wish it were in my power to invite the reader to consider the pupa
state of these insects, as he would find them interesting in various
points of view. Perhaps the following passage from an ingenious writer
may have this effect.
“Some of these creatures crawl for a time as helpless worms upon the
earth, like ourselves; they then retire into a covering, which answers
the end of a coffin or a sepulchre, wherein they are invisibly
transformed, and come forth in glorious array, with wings and painted
plumes, more like the inhabitants of the heavens than such worms as they
were in their former state. This transformation is so striking and
pleasant an emblem of the present, the intermediate, and glorified state
of man, that people of the most remote antiquity, when they buried their
dead, embalmed and inclosed them in an artificial covering, so figured
and painted, as to resemble the caterpillar in the intermediate state;
and as Joseph was the first we read of that was embalmed in Egypt, where
this custom prevailed, it was probably of Hebrew original.”
The eggs of moths and butterflies, particularly the phalæna neustria,
see Plate X. Fig. 1 to 6. The bodies and heads of many libellulæ.
Many of the ichneumon flies, spheges, and wasps, head of the hornet,
sting of ditto, collectors of the bee, many sorts of muscæ, or flies
with two wings, especially those whose bodies are highly coloured; acari
or ticks; phalangium cancroides, see Plate XVIII. Fig. 1 and 6. Some
spiders, but the eyes of all; the oniscus or wood-louse, julus, and
scolopendra.
The feathers of peacocks, and many other birds, have a grand effect when
viewed in the opake microscope, as have also some species of ferns,
mosses, and wood cut transversely. Madrepores, millepores, sponges,
corallines, &c. exhibit wonderful appearances not discernible to the
naked eye. Parts of echini or sea eggs, spines of ditto; these may also
be cut transversely to shew their construction. Minute shells dissected,
skin of many species of fish, particularly the lump-sucker, see Plate
XVIII. Fig. 2. Sole fish, Plate XIX. Fig. 5. and the rasp fish from
Otaheite; also the skins of snakes, lizards, guanas, &c. &c.
The exterior form, and even the interior structure of the generality of
vegetable seeds, have been supposed by some so much alike in the several
kinds, and of so little curiosity and beauty in the whole, that they
have scarcely been regarded by the curious; but when nearly examined
with the help of microscopes, they are found to be worthy of a greater
attention; those which appear most like to one another when viewed by
the naked eye, often proving as different, when thus examined, in their
several forms and characters, as the different genera of any other
bodies in the creation. If their external forms carry all this variety
and beauty about them, their internal structure, when laid open by
different sections, appears yet more admirable.
The seed of the greater maple, which we commonly, but improperly call
the sycamore tree,[148] consists of a pod and its wing; two of these
grow upon a pedicle, with the pods together, which makes them resemble
the body of an insect with its expanded wings: the wings are finely
vasculated, and the pods are winged with a fine white down resembling
silk; this contains a round compact pellet, covered with a brown
membrane that sticks very closely to it. When this is pulled off,
instead of discerning a kernel, as in other seeds, there appears an
entire green plant folded up in a most surprizing manner. The pedicle of
this is about two-eighths of an inch long, and its seminal leaves of
about six-eighths each; between these the germina of the next pair of
leaves are plainly visible to the naked eye, but with a microscope they
are seen with the greatest beauty and perfection.
[148] The Acer pseudo-platanus, Hudsoni Fl. Angl. p. 445. Parkinson
calls it acer majus, adding, sycomorus falso dictum. Hudson, however,
agrees with Hunter in his edition of Evelyn’s Sylva, in affixing to it
the English term greater maple or sycamore. EDIT.
The seed of the musk scabious is beautiful in its shape and structure.
The calix or cup which contains the seed is of an octagonal form, and
makes an appearance like a fine vase, having scallopped edges, and
toward the inner part of the edge a white ruffled membrane. The ribs run
down from its mouth, which is bell-fashioned, and becoming narrower
downward, form obtuse angles by continuing from the bend to form the
bottom of the vase. Between these ribs, down to the beginning of the
narrow part, it is clear, though not wholly transparent, and from thence
to the bottom the ribs are hairy. This vase contains the seed, wherein
appears first its thick body, which runs up with a narrow neck, till it
divides into five spiculated fibres, whose spiculæ are determined
upwards, and are thereby prepared to cause the seed to recede from any
thing that might injure it on being touched. The bodies of the vases,
when first ripe, are of a fine lemon yellow, but grow by long keeping
darker; and the bason formed by the roots of the minute fibres is of a
fine green, but the fibres themselves of a shining brown, like brown
sugar-candy, as their spines are also.
These, and a number of similar beauties in this part of the creation,
are described at large by Dr. Parsons, in his work entitled, “The
Microscopic Theatre of Seeds.”[149] Most kinds of seeds should be
prepared for a microscopical examination by steeping them in warm water
till their coats are separated, and their seminal leaves may then be
opened without laceration. But seeds, while dry, and without any
preparation, are of an almost infinite variety of shapes, and afford a
number of pleasing objects for the microscope.
[149] This curious work was published in the year 1745. It was the
author’s intention to have comprised the whole design in four volumes
quarto, but the first volume only appeared. It contains the etymology,
synonyma, and description of the several plants and their flowers,
with an account of their medical virtues, and an explanation of
botanical terms. As the work is in but few hands, and a copy not easy
to be procured, I flatter myself that extracts from those parts
containing the microscopical descriptions will form an agreeable
addition to these Essays; which the reader will accordingly meet with
in the following chapter. EDIT.
One of the most interesting scenes in microscopical botany is exhibited
in mouldiness. Those miniature plants seem to bear the same relation to
the vegetable kingdom that the animalcula infusoria do to the animal;
they were formerly considered as shapeless and unformed masses, but we
now view them with surprize and pleasure taking their place in the great
scale of organized beings, and presenting us with some of the most
striking characteristics of vegetables.
OF TRANSPARENT OBJECTS.
We may select from the elytra, or upper wings of beetles, many beautiful
objects, the construction of these will be found to differ very much;
the membranaceous wings, as in the scarabæus solstitialis or small
cock-chaffer; blatta Americana or cockroach; all the grylli, as locusts,
grasshoppers, &c. Among the cicadas, the elytra of the nervosa are the
most elegant, the nerves are elevated, and curiously spotted with brown.
The elytra of the cimices or field bugs, which are a very numerous
tribe, afford a great variety of objects; we may select from these as
the most beautiful the elytra of the cimex baccarum and the cimex
striatus, Plate XX. Fig. 1. The elytra of the fulgora candelaria, from
China, differ essentially from all others.
The under or more transparent wings of beetles excite our attention even
more than the upper or crustaceous ones; for whether we consider the
delicacy of their texture, the great weight that many of them are
calculated to sustain in the air, or the very curious manner in which
they fold them up under the upper case, their mechanism must astonish
and delight us; no two genera will be found alike, though every
individual of the same genus will be exact. The wing of the forficula
auricularia or earwig, Plate XIV. is an elegant specimen of the manner
of their folding; this wing folds under a case not one-eighth of its
size.
The under wing of the blatta orientalis, or beetle common in most
kitchens, appears to unite the elytra and transparent wings, partaking
in some degree of both.
Among the membranaceous or more transparent winged insects, the variety
is endless, each genus differing essentially from the other; some
appearing full of membranes or nerves, curiously disposed; others,
again, with scarce any, like a clear piece of talc or isinglass; some
exhibit a curious ground-work of points, which on close examination
prove short hairs, while the nerves of others are furnished with little
scales or feathers, as in some species of the gnat. The wings of many
muscæ are coloured with black, brown, and white, in clouds, spots,
stripes, &c. &c.
The libellulæ or dragon-flies alone afford a great variety, not only in
form but colour; these are all furnished with numerous and very strong
nerves, adapted to the velocity of their flight. The wings of the
ephemera or may-flies, are much more delicate, these flies rest with
their wings erect. The phryganeæ differ very much from the foregoing,
and also from one another; their under wings fold, and their upper ones
are of a stronger texture, many of them so much resembling small moths
as not easily to be distinguished from them: these are all found in the
vicinity of ponds and marshy places. In the hemerobii a wonderful degree
of elegance is exhibited in the disposition of the nerves which compose
their wings, each nerve being adorned with hair in a beautiful manner;
there are many species of these flies equally beautiful, a specimen is
given in Plate XV. The ichneumon fly has four transparent wings, the
inferior ones smaller, and more delicate than the superior; the tube
through which the female deposits its eggs is an additional object well
worth attention. The wings of wasps are folded longitudinally; the wings
of the large bee are very curious. Gnats in general, and the various
species of tipulæ, together with the clouded and variegated wings of the
muscæ, tabani, &c. increase the catalogue beyond the power of
enumeration; in short, there is not a wing but has its particular
beauties, and will amply repay the attentive observer. The currant
sphinx moth connects the transparent and farinaceous wings, partaking of
both; the white plumed, and many-plumed moths, exhibit wings totally
different from all the rest; many other small moths furnish wings
sufficiently transparent for observation, the fringe or edges being
remarkably beautiful.
OF THE PULEX IRRITANS, OR COMMON FLEA.
Many small insects that are not too opake, may be viewed and examined as
transparent objects; some of these having been particularly noticed by
the early microscopic writers, it will be necessary to enumerate a few
of them, as without it the work might be deemed incomplete. Every one is
acquainted with the agility and blood-thirsty disposition of the flea,
of the caution with which it comes to the attack, and the readiness with
which it avoids pursuit. It belongs to the class aptera, has two eyes,
six feet particularly constructed for leaping, the antennæ or feelers
are filiform, or rather moniliform; the rostrum is inflected, setaceous,
and armed with a sting; the belly is compressed. This creature is
produced from eggs, which it deposits on the animals that afford it
food, or affixes them to the wool of blankets, rugs, &c. These eggs in
about a week are hatched into small larvæ or worms, which are of a
whitish colour, with a slight tinge of reddish, and adhere closely to
the body of the animal, or other substance on which they are produced;
in a fortnight they come to a tolerable size, and are very lively and
active; but if they be touched, they roll themselves up in a ball. At
this period they prepare themselves for their pupa or chrysalis state,
by inclosing themselves in a loosely-spun web, or diffused envelopement
of a very soft, silky, or rather cotton-like appearance, and of a white
colour. In this the larva changes into a chrysalis, out of which in
about twelve days emerges the animal in its perfect state, armed with
powers to disturb the peace of an emperor, and occasion uneasy
sensations in the fairest bosom.[150]
[150] Notwithstanding the inconveniences attending this little insect,
and the general disapprobation which its frequent intrusion occasions,
there is something pleasing in the appearance of the flea; all its
motions are elegant, and all its postures indicate agility. The shelly
armour in which it is enveloped, is in a state of perpetual
cleanliness; while the muscular power which it is capable of exerting
is so extraordinary, as justly to excite our wonder at so much
strength confined, and concentrated as it were, in so small a space.
The flea, like many other insects, is eminent for its powers of
revivescence, and will frequently recover after being placed in
situations very unfavourable to animal life. Some of the coleopterous
insects are, however, capable of exhibiting far more striking examples
of suspended animation. Nat. Misc. vol. v. EDIT.
It is difficult to obtain such a view of the flea, as will display the
mechanism and apparatus belonging to the head; these parts are but
imperfectly represented in the celebrated drawing of Dr. Hooke in his
Micrographia. The neck is long, finely arched, and much resembles the
tail of a lobster; the body is covered all over with a polished suit of
sable armour, formed of a hard shelly substance, curiously jointed and
folded over one another, and yet yielding to all the nimble motions of
the little animal; the edges of the scales are curiously set with short
spikes or hairs: it has two sharp eyes to look before it leaps, for
which purpose its legs are excellently adapted, having three large
joints in each, besides several smaller ones. These joints are so
contrived, that it can as it were fold them up one within another; in
leaping, they all spring at once, and the whole strength of the insect
is exerted. The flexure of the fore legs is forward, that of the hind
legs backward. They are all very hairy, and terminated by two long
hooked sharp claws; the two fore legs are placed very near the neck, and
often conceal the proboscis from our view, the other four join all at
the breast: the proboscis or sucker with which it penetrates the skin,
is placed at the end of the snout, and is not easily seen except the two
fore legs are first removed; in it are included a couple of darts or
lancets, which, after the proboscis has made an entrance, are thrust
farther into the flesh, and make the blood flow from the adjacent parts,
occasioning that round red spot, with a hole in the center of it, called
a flea-bite.
OF THE CIMEX LECTULARIUS, OR BED BUG.
Various are the antipathies of mankind, but all appear to unite in their
dislike to this animal and the louse, and to detest them as their
natural and nauseous enemies. The bug “intrudes upon the peace of
mankind, and often banishes that sleep which even anxiety and sorrow
permitted to approach: the night is the season when the bed bug issues
from its retreat to make its depredations; by day it lurks in the most
secret parts of the bed, takes the advantage of every chink and cranny
to make a secure lodgement, and contrives its habitation with so much
art, that scarce any industry can discover its retreat; but when
darkness promises security, it then issues from every corner of the bed,
drops from the tester, and crawls from behind the arras, and travels to
the unhappy patient, who vainly wishes for rest and refreshment.”
Linnæus is of opinion that this insect is not originally of European
growth, but was imported from some other country. It is not only
disagreeable on account of the extremely offensive smell proceeding from
it, but also because of the rapidity with which it increases, and the
voraciousness of its appetite. It has two brown small prominent eyes,
two antennæ, and a crooked proboscis, which lies close under the breast.
Instead of wings, we find on the first ring of the belly two flat pieces
which entirely cover it, and extend towards the sides. These plates, the
trunk, and the head, are amply set with hairs. The proboscis is divided
transversely into four parts, which are probably so many articulations;
this piece is best seen on the under side of the bug, being bent flat on
the belly, and reaching half way down the body; but the mechanism of
this, as well as other parts of these minute insects, cannot be
perfectly understood, but by an accurate examination with the
microscope. It has six legs, each of which has three joints; these legs,
like those of the fly, are formed for running, not leaping; the skin is
shagreened, and the separation of the rings usually marked by a smooth
shining band. On the belly, at a small distance from the edge, a set of
circular spots may be perceived, two on each ring, except the last;
these are the spiracula. Examined internally, we find one large artery,
a stomach, and intestines. The instant it perceives the light, it
endeavours to gain its obscure habitation, and seldom fails in making
good its retreat.
OF THE PEDICULUS HUMANUS, OR LOUSE.
“Whenever wretchedness, disease, and hunger seize upon man, the louse
seldom fails to add itself to the tribe, and to increase in proportion
to the number of his calamities.”
When the human louse is examined with the microscope, its deformity
fills us with disgust. In the head we may distinguish two fine black
eyes, looking backward and fenced with hair; near these are the two
antennæ, each of which has five joints set with short bristles; the
fore-part of the head is rather long, the hinder more round or obtuse;
there is a small part that projects from the nose or snout, this serves
as a sheath or case to the proboscis or piercer, which the creature
thrusts into the skin to draw out the blood and humours which are its
destined food, for it has no mouth which opens in the common way.
This proboscis has been estimated to be seven-hundred times smaller than
a hair; it is contained in another case within the first, and can be
drawn in or thrust out at pleasure; the skin is hard and transparent.
From the under side proceed six legs, each of which has five joints, and
terminates in two unequal hooked claws, these it uses as we would a
thumb and finger; there are hairs between the claws, as well as all over
the legs; the body finishes in a cloven tail, which is generally
covered, and partly concealed by hairs.
From the extreme transparency of its skin, the internal parts may be
seen to greater advantage than in any other insect; as, the various
ramifications of the veins and arteries, in which a kind of regular
pulsation may be observed, as well as the peristaltic motion of the
intestines, which is continued from the stomach to the tail. When the
louse feeds, the blood rushes like a torrent into the stomach, moving
with so strong a propulsion and contraction, as appears very curious.
The digestive powers are so great, that the colour of the blood changes
in its passage from thick and black at its first entrance, to a fine
ruby colour in the intestines, and nearly white in the veins. Its
greediness is so great, that the excrement contained in the intestines
is ejected at the same time, to make room for this new supply. There is
scarce any animal that multiplies so fast as this unwelcome intruder;
the moment it is excluded from the egg it begins to breed.
It would be endless to describe the various creatures which go under the
name of lice, and swarm upon every part of nature. The reader, desirous
of a more particular account of those which infest various animals, will
obtain full satisfaction, by consulting Rhedi’s Treatise de Generatione
Insectorum.
OF THE ARANEA, OR SPIDER.
The spider is another insect which is often examined with the
microscope, and certainly affords much matter for observation. “Formed
for a life of rapacity, and incapable of living but by blood, all its
habits are calculated to deceive and surprize; it spreads toils to
entangle its prey; it is endued with patience to expect its coming, and
is possessed of arms and strength to destroy it when fallen into the
snare.”
“ -------- To heedless flies the window proves
A constant death; where, gloomily retired,
The villain spider lives, cunning and fierce,
Mixture abhorr’d; amid a mangled heap
Of carcases, in eager watch he sits,
O’erlooking all his waving snares around.
Near the dire cell the dreadless wanderer oft
Passes, as oft the ruffian shews his front;
The prey at last ensnar’d, he dreadful darts
With rapid glide along the leaning line;
And fixing in the wretch his cruel fangs,
Strikes backward grimly pleas’d: the flutt’ring wing
And shriller sound declare extreme distress,
And ask the helping hospitable hand.” THOMSON.