the medical virtues of the cantharis, have occasioned them to be
considered as very extensive and valuable articles of commerce. The
benefits derived from the bee and the silk-worm are universally known;
and spiders, could a method be devised to induce them to live in
harmony, might also be productive of very essential advantages to the
human race. EDIT.
Malignant must be the mind of that person; with a distorted eye he must
have contemplated creation, who can suspect that it is not the
production of infinite benignity and goodness. How many clear marks of
benevolent intention appear every where around us? What a profusion of
beauty and ornament is poured forth on the face of nature? What a
magnificent spectacle presented to the view of man? What a supply
contrived for his wants? What a variety of objects set before him, to
gratify his senses, to employ his understanding, to entertain his
imagination, to cheer and gladden his heart? Indeed the very existence
of the universe is a standing memorial of the goodness of the Creator;
for nothing except goodness could originally prompt creation. No new
accession of felicity or glory was to result to him from creatures whom
he made: it was goodness communicating and pouring itself forth,
goodness delighting to impart happiness in all its forms, which in the
beginning created the heaven and the earth. Hence those innumerable
orders of living creatures with which the earth is peopled, from the
lowest class of sensitive being to the highest rank of reason and
intelligence. Wherever there is life, there is some degree of happiness;
there are enjoyments suited to the different powers of feeling; and
earth, air, and water, are with magnificent liberality made to teem with
life.[48]
[48] Blair’s Sermons.
Let us not then slight, or deem that unworthy our notice, in which
immensity is so conspicuous; or that trivial, in which there is such a
manifestation of infinite beneficence; but rather let those striking
displays of creating goodness call forth, on our part, responsive love,
gratitude, and veneration. To this Great Father of all existence and
life, to Him who hath raised us up to behold the light of day, and to
enjoy all the comforts which his world presents, let our hearts send
forth a perpetual hymn of praise. Evening and morning let us celebrate
Him who maketh the morning and the evening to rejoice over our heads;
who “openeth his hand and satisfieth the desire of every living thing.”
Let us rejoice that we are brought into a world, which is the production
of infinite goodness; over which a supreme intelligence presides; and
where nothing happens but by his divine permission for the wisest
purposes. Convinced that he hateth not the works which he hath made, nor
hath brought creatures into existence merely to suffer unnecessary pain,
let us even in the midst of sorrow, receive with calm submission
whatever he is pleased to send; thankful for what he bestows; and
satisfied that, without good reason, he takes nothing away.
Such, in general, are the effects which meditation on the works of the
creation ought to produce. It presents such an astonishing conjunction
of power, wisdom, and goodness, as we cannot behold without religious
veneration.
In short, the world around us is the mighty volume wherein god hath
declared himself; a picture wherein his perfections are displayed. The
book of nature is written in a character that every one may read; it
consists not of words, but things; it is a school where GOD is the
teacher. All the objects of sense are as the letters of an universal
language, in which all people and nations have a common interest; the
Creator himself has made this use of it, revealing his will by it, and
referring man to it for instruction. Hence the universal agreement
between nature and revelation; hence, also, he that can understand GOD
as the Fountain of truth and the Saviour of men in the holy scriptures,
will be better enabled to understand and adore him as the fountain of
power and goodness in the natural creation. Thus will philosophy and
divinity go hand in hand, and shew that the world was made, as the
scriptures were written, for our instruction; and that the creation of
GOD is a school for Christians, if they use it aright.[49]
[49] It is a curious, though melancholy subject of contemplation, to
observe how different have been the sentiments of learned and
reputedly pious men in times less enlightened; a period when attention
to, or compassion for, the animal creation could find no place in a
breast that withheld and denied the mercy of God unto men; when mercy
itself was deemed heresy! Even in prior and purer times it was
affirmed that “It is absurd, and a disparagement to the majesty of GOD
to suppose him to know how many insects there are in the world, or how
many fishes in the sea; yea, that such an idea of the Omniscience of
GOD would be foolish flattery to Him, and an injury to ourselves.” For
the satisfaction of the learned reader, I shall here quote the
original. “Absurdum est ad hoc Dei deducere Majestatem, ut sciat per
momenta singula quot nascantur culices, quotve moriantur; quæ cimicum
et pulicum et muscarum sit in terra multitudo; quanti pisces in aqua
natent, et qui de minoribus majorum prædæ cedere debeant. Non simus
tam fatui Adulatores Dei, ut dum potentiam ejus ad ima detrahimus in
nos ipsos injuriosi simus.” HIERONYMI Comment. in Abac. Lib. 1. Edit.
Basil. Tom. vi. p. 187. EDIT.
A GENERAL DESCRIPTION OF INSECTS.
The subjects of that part of the creation we are now going to survey,
merit our attention as exceeding the rest of animated nature in their
numbers, the singularity of their appearance, and the variety of their
forms. Earth, air, and water are filled with hosts of them. Being for
the major part very small, and myriads so diminutive, as even to be
imperceptible to the unassisted eye, our knowledge of them, and their
component parts would be extremely circumscribed and imperfect, were it
not for the advantages derived from the use of the microscope; but
happily possessed of this valuable instrument, an inexhaustible source
of entertainment and instruction is afforded to the curious inquirer
into the wonders of nature. The beauties of the minuter parts of
creation are not more hidden from our unassisted sight, than the ends
and purposes of their œconomy from slight and superficial observation;
the microscope does not more amaze and charm as with a discovery of the
first, than the application of our faculties in investigating the
latter.
The name of INSECT has been appropriated to these small animals on
account of the sections or divisions that are observable in the bodies
of the greatest part of them; though, perhaps, it is impossible to find
any precise term that shall embrace the whole genera, as many
particulars must be described before we can attain an exact notion of
these animals and their structure.
An insect is now generally defined to be, an animated being whose head
is furnished with antennæ; that is destitute of bones, but which,
instead thereof, is covered with a very hard skin; that has six or more
feet; and that breathes through spiracula, or pores placed in the side
of the body.
To be more particular, quadrupeds, birds, and fishes have an internal
skeleton of bones, to which the muscles are affixed; but the whole
interior body of insects is composed of soft flesh, and the muscles are
attached to an external skeleton, serving the double purpose of skin and
bone.
Insects are by most writers considered as divided into four principal
parts: the caput, or head; the thorax, or trunk; the abdomen, or belly;
and artus, or limbs. A perfect knowledge of these parts, and their
several subdivisions, is requisite for those who are desirous of forming
accurate ideas of these minute animals, or who wish to arrange them in
their proper classes.
The head is affixed to the thorax by a species of articulation or joint;
it is the principal seat of the senses, and contains the rudiments of
the brain;[50] it is furnished with a mouth, eyes, antennæ, a forehead,
a throat, and stemmata. In the greater part of insects the head is
distinctly divided from the thorax, but in others it coalesces with it.
The head of some insects is very large compared with the size of their
bodies; the proportion between the head of the same insect is not always
similar; in the caterpillars with horny heads it is generally small,
before they moult or change their skin, but much larger after each
moulting. The hardness of the exterior part of the head prevents its
growth before the change; it is, consequently, in proportion to the body
very small; but when the insect is disposing itself for the change, the
internal substance of the head retires inwards to the first ring of the
neck, where it has room to expand itself; so that when the animal quits
the skin, we are surprized with a head twice the former size; and, as
the insect neither eats nor grows while the head is forming, there is
this further circumstance to be remarked, that the body and the head
have each their particular time of growth: while the head expands and
grows, the body does not grow at all; when the body increases, the head
remains of the same size, without any change. The heads of all kinds of
insects, and their several parts, form very pleasing, as well as most
diversified objects for the opake microscope.
[50] Fabricius Philos. Entomolog. p. 18.
Os, the mouth, is a part of the insect to which the naturalist will find
it necessary to pay a very particular attention; Fabricius goes so far
as to assert that, without a thorough knowledge of the mouth, its form,
and various appendages, it will be impossible ever to discriminate with
accuracy one insect from another. In the structure of the mouth
considerable art and wisdom is displayed; the diversity of the figure is
almost as great as the variety of species. It is usually placed in the
forepart of the head, extending somewhat downwards; in the chermes,
coccus, and some other insects, it is placed under the breast. In some
insects, the mouth is forcipated, to catch, hold, and tear the prey; in
others, aculeated, to pierce and wound animals, and suck their blood; in
others, strongly ridged with jaws and teeth, to gnaw and scrape out
their food, carry burdens, perforate the earth, nay the hardest wood,
and even stones themselves, for habitations and nests for their young.
Others are furnished with a kind of tube or tongue, at one time
moveable, at another fixed; with this they suck the juices of the
flowers: in some again the tongue is so short, as to appear to us
incapable of answering the purpose for which it was formed, and the
oestri appear to have no mouth.
Maxillæ, the jaws, are generally two in number; in some, four; in
others, more. They are sometimes placed in an horizontal, sometimes in a
transverse direction; the inner edge is serrated, or furnished with
small teeth, as in the cicada, nepa, notonecta, cimex, (bug,) aphis, and
remarkably so in some curculeones.
The rostrum, or proboscis, is in general a very curious and complicated
organ; it is the mouth drawn out to a rigid point. In many insects of
the hemiptera class, it is bent down towards the breast and belly. It
has by some writers been considered as serving at once the different
purposes of mouth, nose, and windpipe, enabling the insect to extract
the juices of plants, communicate the sensation of smelling, and convey
air to the body.
Lingua, the tongue, is a taper and compact instrument, by which the
insect obtains the juices of plants. Some can contract or expand it,
others roll it up with dexterity; in some it is inclosed within a
sheath. It is taper and spiral in the butterfly, tubular and fleshy in
the fly; in all affording agreeable amusement for the microscope. To
exemplify which in one or two instances, while it relieves the reader
from the tediousness of narration, will, it is hoped, animate him to
farther researches on the subject.
OF THE PROBOSCIS OF THE BEE.
Every day’s experience shews that the more we penetrate into the hidden
recesses and internal parts of natural bodies, the more we find them
marked with perfection in form and design; of the truth of which
observation the minute apparatus now to be described will, no doubt,
ensure conviction. Swammerdam, when speaking thereof, breaks out into
this pious and humble confession: “I cannot refrain,” says he, “from
confessing to the glory of the Immense and Incomprehensible Architect,
that I have but imperfectly described and represented this small organ;
for, to represent it to the life in its full perfection, as truly most
perfect it is, far exceeds the utmost efforts of human knowledge.”
From what has here been said, it will be easy to perceive, that the
limits of these Essays will not permit our entering largely into a
description of the minute parts of the proboscis of the bee; for an
ample account of which recourse must be had to the works of Swammerdam
and Reaumur. The last writer, like a skilful workman who takes to pieces
a watch which he himself has made, exhibits to you the several parts of
which it is composed, and explains their fitness, their adjustments,
their uses, the play of the pivots, springs, and pillars; for all these
parts, and many more, are to be found in the proboscis of a bee.
It is by this small instrument that the bee procures the food necessary
for its subsistence. In a general view, it may be considered as
consisting of seven pieces; one of these, i i, b c, Fig. 3. Plate XIII.
is placed in the middle; this is supposed to be pervious, and to
constitute what may be properly called the tongue; the other six smaller
parts or sheaths, disposed in three pairs, are placed on each side of
the former: they not only assist in extracting and gathering the honey
from the flowers, but they also protect and strengthen the part. The
proboscis itself is very curiously divided; the divisions are elegant
and regular, and are beset all round with shaggy triangular fibres or
villi, distributed in beautiful order: these divisions, though very
numerous, appear at first sight as a number of different articulations.
The tongue, considered with respect to its length, may be said to have
three articulations; one with the head, then a kind of cylindrical horny
substance, which forms as it were a base for the true tongue, which is
not horny, but soft, fleshy, and pliable.[51]
[51] Philos. Trans. for 1792, Part I.
The two pieces a a of the exterior sheath are of a substance partly
between bone and horn, and partly membranaceous; they are set round with
fibres, and are furnished with air vessels, which are distributed
through their whole texture; the upper ends f f of this sheath appear to
be a little bent, but can be straitened by the bee when they are applied
to the proboscis. At d d are two articulations, by means of which the
pieces a a may be occasionally bent. The joints contribute towards
bending the proboscis downwards, or rather underneath, against the head.
These sheaths, together with two interior ones e e, assist in defending,
covering, and protecting it from injuries; it is also probable that they
promote the descent of the honey, by pressing the proboscis. The parts k
k of this sheath have been called by some writers the root.
The two parts e e of the interior sheath are placed higher than those of
the exterior one; they originate at g g on the proboscis itself, and
near that part or articulation, by which the bee can upon occasion bend
the proboscis; this sheath, therefore, always moves with the middle part
i i, and is carried forward by it, the exterior sheath being left
behind, because its attachments and origin are below that of the
proboscis. The pieces e e are very similar in structure to those of a a,
only that each of them has on the upper part three joints, the lower one
is much longer than the other two; they are all of them surrounded with
short fibres. The smaller articulated pieces never lie close to the
proboscis, nor cover it, but are only placed near it, the two upper
joints projecting outwards, as in this figure, even when the whole
apparatus is shut up as much as possible. Swammerdam thinks these joints
are of essential use to the bee, acting as it were in the manner of
fingers, and assisting the proboscis, by opening the leaves of the
flowers, and removing other obstructions from it; or like the two fore
feet of the mole, by the help of which it pushes the earth from the
sides both ways, that it may be able with its sharp trunk to search for
its food more conveniently. There are two smaller pieces or sheaths, m
m, near the bottom of the proboscis; these cannot be well seen without
removing the sheath e e.
The proboscis is partly membranaceous, and partly of a gristly nature;
the lower part is formed in such a manner, that it will swell out
considerably, by which means the internal cavity may be prodigiously
enlarged, and rendered capable of receiving a very large quantity of
native and undigested honey, and larger than might be expected from its
size. When the proboscis is shut up and inactive, it is very much
flattened, and is three or four times broader than it is thick. The
edges are always round; it grows tapering, though very gradually,
towards the extremity. The lower and membranaceous part of the trunk has
no fibres or villi on it, but is covered with little protuberant
transparent pimples, that are placed in regular order, and at equal
distances from each other, resembling the little risings observable on
the skin of birds when the feathers have been plucked off. They are
probably glandules, and may have a considerable share in changing or
preparing the honey that is swallowed or taken up by the proboscis. Down
the middle of the proboscis there is a tube of a much harder nature than
the sides, it grows gradually smaller towards the top; at this place the
tongue itself is extremely villous, having some very long villi at the
point; whether they are open tubes, or whether they only serve as so
many claws, to keep it in its proper place while in action, has not been
determined; Mr. John Hunter conceives them to act somewhat like
capillary tubes.
The proboscis terminates in a small cylinder c, at the top of which
there is a little globule or nipple; the bee can contract this
cylindrical part, and the little membrane in which the villi are fixed,
into a much smaller compass, and draw it inwards. The exterior sheaths
lap over each other on the upper part, so that the outside of the
proboscis is protected by a very strong double case, a covering that was
unnecessary for the under part; because when this instrument is in use
the sheaths are opened, but when it is inactive, it is so folded that
the under part is protected by the body of the bee. Withinside the
exterior sheath, and near the bottom q, are two levers, which are fixed
to the end of the proboscis, and by which it is raised and lowered.
Swammerdam thinks that the honey is, as it were, pumped or sucked up by
the bee through the hole at the end b of the tongue; he does not seem to
have discovered the apertures which are on the cylindrical part, near
the end b. But Reaumur is of opinion that it is used to lap up the
fluid, which is then conveyed down between the sheath to the mouth of
the bee. To ascertain this, he placed a bee in a glass tube, the inside
of which was rubbed over with honey, and little pieces thereof placed in
different parts; the bee placed the tongue on the honey; stretching the
end beyond the piece thereof, she bent it into the form of a bow, and
inserted the most convex part of the bow into the honey; by rubbing the
glass backwards and forwards with this part, she soon cleaned that
portion to which it was applied, conveying the honey afterwards to the
throat by the vermicular motion of the tongue.
If you attentively observe a bee, when it has placed itself on a
full-blown flower, the activity and address with which it uses this
apparatus will be very conspicuous. It lengthens the end, and applies it
to the bottom of the petals or leaves of the flower, moving it
continually in a vast variety of different directions; lengthening and
shortening, bending and turning it in every possible way, to adapt it to
the form, &c. of the leaves of the flower. These various movements are
executed with a promptitude that surpasses all description.
The whole of this curious apparatus can be folded up into a very small
compass under the head and neck. The larynx, or that part next to the
head, falls back into the neck, which brings the extreme end of the
first portion of the proboscis within the upper lip, or behind the two
teeth; then the whole of the second part is bent down upon and under the
first part, and the two last sheaths or scales are also bent down over
the whole; so that the true tongue is inclosed laterally by the two
second horny sheaths, and over the whole lie the two first.
OF THE PROBOSCIS OF THE BUTTERFLY.
From the tongue of the bee, let us now direct our attention to that of
the butterfly. This is a spiral substance, somewhat resembling the
spring of a watch when wound up, consisting of eight rounds; by means of
a pin you may gently pull it out to its full length; it grows gradually
tapering from the base, at the end it divides or separates into two
tubes, each furnished with little organs of suction; probably, it is by
these that it extracts the juices on which it feeds, and not by the
extreme ends of the tongue. As the butterfly has no mouth, the proboscis
is the only alimentary organ; when separated from the insect, it will
often unroll itself, then wind and coil itself up again, continuing
these motions at intervals for a considerable time.
OF THE PROBOSCIS OF THE CULEX OR GNAT.
The proboscis of the gnat consists of a great number of extremely
delicate pieces, all concurring to one purpose; this is the instrument
with which it strikes the flesh, and sucks the blood of animal bodies.
The only part exhibited to the naked eye is the sheath, which contains
all the other pieces. This sheath is a cylindrical tube, which is slit
in such a manner, that the insect can separate it from the dart, and
bend it more or less in proportion as the dart is plunged into the
wound. From this tube the sting is darted, which consists of five or six
blades or lancets of exquisite minuteness, lying one over the other;
some of these are sharpened like a two-edged sword, while others are
dentated and barbed at their extremities like the head of an arrow. The
instant the gnat lances this bundle of darts into the flesh, and
penetrates a vein, a drop or two of fluid is by it insinuated into the
wound, by which the blood is attenuated, and the blades acting as so
many capillary tubes, the blood ascends in them, and is conveyed into
the body of the gnat. The injected fluid also by its fermentation causes
that disagreeable and teazing sensation of itching, to which most
persons are subjected, after having sustained an attack from one or more
of these little animals.[52]