essays - Georg-Simon-Ohm Hochschule Nürnberg

ESSAYS
ON niE
M I C R 0 S C 0 P E .. · "
*

.
XlV PREFA€E.
Though all nature teems "\vith objects for . the microscopic
observer, yet such is the indolence of the human mind, or such
its inattention to what is obvious, that among the purchasers of
microscopes many have complained that they knew not what
subjects t'o apply to their instrument, or where to find objects for
examination. To obviate this complaint, a catalogue is here
given, which is interspersed with the description of a few insects,
and other objects, which could not be conveniently introduced in
the foregoing chapters. By this . catalogue it is hoped that the
use of the microscope will be extended, and the path of observation
facilitated.
To avoid the formal parade of quotation, and the fastidious
charge of plagiarism, I have subjoined to this preface a list of the
authors "rhich have been consulted. As my extracts were made
at very distant periods:, it vvould have been impossible for me to
recollect to whom I was indebted for every new fact or ingenious
observation.
The plates \Vcre drawn and engraved with a view to be folded
up with the work; but as it is the opinion of many of my friends
that they would, by this mean, be materially injured, I have been
advised to have them stitched in strong blue paper, and leave it
to the purchaser to dispose of them to his own mind.

A COKCISE HISTORY OF
to establish an opinion of its merit \vith the rest of the world, anJ
hand do-wn the name of the inventor to succeeding agcs. 1\Ien
of great literary abilities are too apt to despise thc first da\vnings
,, of invention, not considering that all real knowledge is progressive,
and that vvhat they deem tri:fiing, may be the first and nccessary
link to a new branch of science.
/
The tnicroscope extends the boundaries of the organs of vision;
enables us to examine the structure of plants and animals; presents
to the eye myriads of beings, of whose existence vve had before
formed no idea; opens to the curious an exhaustless source of
information and pleasure; and furnishes the philosopher with an
unlimited field of investigation. "It leads," to use the words of an'
ingenious vvriter, " to the discovery of a thousand wonders in the
works of his hand, who created ourselves, as well as the objects
of our admiration; it improves the faculties, exalts the comprehension,
and multiplies the inlets to happiness; is a new source of
praise to him, to whom all we pay is nothing of what we ovve;
and, while it pleases the imagination with the unbouncled treasures
it otfers to the view, it tends to make the whole life one:
continued act of admiration."
lt is not diffieult to :fix the period when the rnicroscope first
began to be generally known, and_ was used for the pu.rpose of
examining minute objects; for, th

.OF THE DOUBLE OR COMPOUND MICROSCOPE. 43
Fig. 5. Plate I. and an eye glass F G. The object B 0 is placed a
little further from the lens than its principal focal distance, so
that the pencils of rays proceeding from the different points of
the object through the lens, may converge to their respective foci,
and form an inverted image of the object at Q P; "\-vhich image is
viewed by the eye through the eye glass F G, which is so placed,
that the image may be in its focus on one side, and the eye at thc
same distance on the other. The rays of each pencil "\-vill be
parallel, after passing out of the glass, till they reach the eye at E,
where they will begin to converge by the refractive powers of
the humours; and after having crossed each other in the pupil,
and passed through the crystalline and vitreous humours, they
will be collected in points on the retina, and form a large inverted
image thereon.
It will be easy, from what has been already explained, to understand
the reason of the magnifying power of a compoup.d
l.Jlicroscope. The object is magnified upon two accounts; first,
beea\l.Se if we viewed the image with the naked eye, it would
appear as much larger than the object, as the image is really larger
than it, or as the distance fR is greater than the distance fb;
and secondly, because this picturc is again magnified by the eye
glass, upon thc principlc explaincd in the foregoing article on
vision, by single microscopcs.
But it is to be noted, that the image formed in the focus of a
lens, as is the case in the compound microscope, di:ffers from the
real object in a very essential particular; that is- to say, the light
being emitted from the object in every direction, renders it visible'
to an eye placed in any position; but the points of the image
formed by a lens, emitting no more than a small conical body of
rays, which arrives from the glass, can be visible only when the
eye is situate within its confine. Thus the pencil, which ema-
F 2
.,

APPARATUS 'l"O THE LUCERNAL MICROSCOPE. 70
A pair of forceps, Fig. g, by which any occasional small object
may be conveniently taken up.
Six large ivory sliders, vvith transparent objects placed between
two plates of talc, ancl con:fi.ned by brass rings, and six small ditto
with ditto. }'ig. 10. Thc larger oncs usually contain a set of
CL1stancc' s :fine vegetable cuttings.
Fourteen wood sliders, containing on each four opake objects,.
and two spare sliders for occasional objects; all fitted to the
cheeks k 1 of the stage. Fig. 11.
Some capillary tubes, Fig. 12, to receive small :fish, and for
-viewing small animalcula. They are to be placed between the
two plates of the stage No. 7, Fig. 4.
A small ivpry double box, containing spare plates of talc and
brass rings, for replacing· any in the small ivory sliders, .when
necessary.
A single lens mounted in a tortoiseshell case, to exaniine minute
objects previous to their being applied to the slidcrs.
Opake objects are easily put on the spare sliders by a wetted
:wafer; and, for good security, gum water may be added ..
For the prices of the lucernal, as weil as all the other sorts of
microscopes, see the list annexed to these Essays ...
"

go
'
APPAHATVS TO CUFF S MICROSCOPE.
p q is the stage or plate which carries the objects; it has a
hole at the center n.
G, a concave mirror, that may be turned in any dircction, to
reflect the light of the candle, or the sky, upon the object.
A LIST OF THE APPARATUS TO CUFF's DOUBLE-COSSTRUCTEO
MICROSCOPE.*
H, a convex lens,to collect the rays of light from the sun or a
candle, and condense them on the object, or to magnify a flower
or other large object placed upon the stage.
L, a cylindrical tube, open at each side, with a concave silver
speculum screwed to the lower end h.
·p, the slider-holder; it consists of a cvlindrical tube, in which
"' '
an inner tube is forced upvvarcls by a spiral spring, it is used to
receive an ivory slider K, \Vhich is to be slid between the plates
h and i. The cylinder P fits the holen in the stage: the hollow
partat k is designed to receive a glass tube N.
R is a brass cone, to be put under the bottom of the cylinder
P, to intercept occasionally some of the rays of light.
S, a box containing a concave and a ftat glass, between which
a smallliving insect may be confined; it is to be placed over the
holen.
* This microscope is made oftentimes with a joint at the bottarn of the main pillar at e, "to
admit placing the instrument into any oblique situation, and connected to the bottom of a
mahogany ehest; on which account" it is by some of the instrument makers ca.lled the Chest
Compound Mtcroscope. EDIT.

[ go ]
LIST OF APPARATUS GENERALLY MADE TO TIIIS 1\IICROSCOPE.
The wheel, with the magnifi.ers, P. Fig. 1.
The body ofthe ,microscope, AB.
'The slider-holder, K.
The tube, with the condensing lens L, to be used by candlelight.
The pin and arm a, either for the above lens, or for the silver
concave speculum e.
The silver concave speculum e, fitted to the arm above, and
used common to all the magnifiers in the wheel and body AB, it
is to reflect the light from the concave or plane mirror 0 belo·w,
upon the opake objects, then called the compound opake microscope.
A silver concave speculum f, with a single magnifier; it scre,vs
to the under part of the arm CD in room of the wheel of magnifi.ers,
and forins then the singleopake microscope.
-
A brass cone g, to place under the stage NI 8, and serves to
diminish the reflected light wheri necessary.
The jointed nippers b, fitted to the stage, to hold any small insect,
or other .opake object.
A cylinder of ivory h, to fix on the pointed end of the nippers, ·
black on one side and white on the other, to make a cantrast to
the opake object uscd.

AND PRESERVJNG TIIE POLYPES. l!i5
Heat and cold has the same effect upon thesc littlc crcatures,
that it has upon those of a larger size. 'They arc animatcd and
enlivened by heat, ·whereas cold renders them faint and languid;
they should therefore be kept in such a degree of heat, that the
water may not bc below temperate.
It is convenient for many cxperiments to suspend a polype
from the surface of the w-ater. To cficct this, takc a hair pencil
in one hand, and hold a pointed quill in the other; with the pencil
loosen the ·polype fro'm the receiver in which it is kept, and
gradually raise it near the top of the "\Vater, so that thc antcrior
end may be next the point of the pencil; then lift it out of the
water, and keep it so for a minute; after which, thrust the point
of the pencil, togethcr with the antcrior end, by little and littlc
under water, until no morc than about the twentieth part of an
inch of the polype's tail re11.1.ains above its surface; at this instant,
with the pointed quill remove that part of the polype from the
pencil \vhich is already in the water, at the same time blowing
against the pol:,ype, by which it will be loosened, and remain out
of the water.
\Vhcn the polypes wcre first uiscovered, l'1fr. Trembley had
some difficulty to firHl out the food which was proper for them;
but he soon discovercd, that a small species of thc milleperle

. TO OBTAIN THE PARTS OF A SIIOOT SEPARATE. l5!J
" Trcatise on the Construction of Timbcr," what he has said;
this, together with the improvements I have made on thc cutting
engine, will enable the rcader to pursue thc subject and extend
it further, both for his own pleasure, and the advantage of thc
pu....:lic.
TUE l\1AXNEP.. OF OBTAI)IflNG TUE PARTSOFA SHOOT
SEPARATE.
In the beginning of April, take a quantity of young branches
from the scarlet oak, and other trees. These are first cut into
lengths, of the growth of different seasons; and thcn part is lcft
entire, part split, and the rest quartered. In this state they are
put into a wicker basket, with large openings, or of loosc 'vork,
and a heavy stone is put in with them; a rope is tied to the handle
of the basket, and it is thrown into a brook of running water:
at times it is taken llp, and exposed a little to the air; it is frcquently
shook about under water, to wash off :61th; and once in
ten days the sticks are examined.
By degrees the parts loosen from one another,. and by gen'tie
ruhhing in a bason of "\Vater just warmed, they ·will be so far
separated, that a pencil brush ·will perfect the business, and afford
pieccs of various sizes, pure, distinct, and clean. One part will
in this way separate at one time, and another, at another; but
by turning the sticks to the water,· ancl · repeating the operation,
in the course of four or :five weeks every part may be obtained
distinct. They are best examincd immediately;, but if any one
wish to preserve them for repeated inquiries, it may be donein
this manner: dissolve half an ounce of alum in two ,quarts of
water; drop the pieces thus separated, for a fcw moments, into
this solution, then dry them upon paper, and put them up in
vials of spirit of wine, no other fluid being so well. adapted to,
preserve these tender bodies.

[ lÖO ]
TO PREPARE THE RIND FOR OBSERVATION.
As the vessels of thc rind are of different diamcters in Yarious
trees, though their construction and that of the. blebs is pcrfcctly
the same in all, it willbebest to choose for this purpose the rind
of a tree wherein they are largest. The rind of the ash-leavcd
maple is finely suited. A piece of this may be obtaincd of two
inches long, and will very successfully answer thc intention.
Such a piece being preparcd without alum or spirit, but dried
from the water in which it · had been macerated, it is to be impregnated.
with leacl in the following manner, to shew the apertures-
by their colour.
Dissolve one drachm of sugar of leadinan ounce and an half
of water; filter this through paper, and pour it into a tea-cup.
Clip o:tf a thin slice of ·what ·was thc lowcr end of the piece _ of
rind as it grew on the tree, and plunge it near an inch deep into
the liquor; keep it upright bet\vcen t\VO pieces of stick, so that
one half or more may be above thc "\Yater; whclm a winc-and-
, "'
water glass over the tea-cup, and set the whole in a ·warm place.
When it has stood two days, take it out, clip off all that part
which was in the liquor, and "throw if away .
.;
. -
, The circumstances here mentioned, trivial as they may seem,
must be attended to = the operatlon will not succeed, even if the
covering-glass be omittcd; it keeps a moist atmosphere about the
rind, and makes its vessels supple.
vVhile this is standing, put into a bason two Ounces of quick
1ime, and an ounce of orpiment; pour upon them a pint and an
half of boi1ing watcr; stir the v;rhole together, and ·when it has
;,tood a day and a night, it will be :fit for use. This is the

I>ISTINGUISHING CRITERIA. OP INSECTS. 217
5. That they do not respire air by the mouth, but that they
inspire and exhale it by means of organs which are placed on
the body.
0. That they move the Ja ws from right to left, not up and
down.
7. That they have neither eye-lid nor pupil.
To these we may also add, that the mechanism resulting from
the LIFE of insects is not of so compound a nature as in animals
of a larger size. They have less variety of organs, though some
of thetn are more multiplied; and it is by the number and situation
of these that their rank in the great scale of beings is to bc
determined.
These characters are often united in the same insect; there are,
howe_ver, some species in which one or two ofthem are wanting.
The student in entomology, vvho wishes to attain a proper
knowledge of the science, and indeed evcry microscopic observer,
not so evident; Barbut, however, snpposes them to possess the sense of hearing in a very distinct
mariner. Many insects, he observcs, are well lmown to be endued with the power of littering
sounds, viz. large beetles, bees, wasps, common flies, gnats, &c. the sphinx atropos squeaks,
· when hurt, nearly as loud as a mause: this faculty certainly must be intended for some purpose,
and as they vaty their cry occasionally, it appears designed to give notice of pleasure or pain, or
some. affection in the creature which possesses it. " The knowledge of their sounds," says he, .
" is undoubtedly confined to their tribe, and is a language intelligible ta them only; saving when
violence pbliges the animal to exert the _voice of nature in distress, craving compassion; then all
animals understand the doleful cry; for instance, attack a bee or wasp near the hive or nest, or
a few of them; the consequence will be, thc animal or animals, by a different toae of voice will
e:x.press his or their disapprobation or pain; that sound is known to the hive to be pl'lintive, and ·
that their brother or brethren require their assistance, and tlle offending party seldom escapes:
, E e
, /

DISTINGUISHING CRITERIA OF INSECTS. 219
Specimens o( English Insects, drawn from Nature, by James
Earbut.*
Class the first. CoLEOPTERA. The insects of this dass have
four wings; the upper ones, called the el ytra, are crustaceous,
being of a hard horny substance; these, when shut, fonn a longitudinal
suture down tbe back, as in the scarabreus, melolontha,
or cockchaffer, &c.
2. HEMIPTERA. These have also four wings; but the elytra
are different, being half crustaceous, half membranaceous: thc
\Yings do not form a longitudinal suture, but extend the one over
the other, as in the gryllus, grasshopper, &c.
3. LEPIDOPTERA. Those which have four membranaceaus
wings covered with fine scales, appearing to the naked eye like
powder or meal, as in the butterffy _and moth.
4. NEUROP'.rERA. These have four membranaceous transparent
wings, which aie generally reticulated, the tail without a
sting, as in the libellula, or dragon fty.
5. HYMENOPTERA. These, like the preceding dass, have four
membranaceous naked wings; but the abdomen is furnished with
a sting, as in the bee, wasp, ichneumon, &c.
6. DIPTERA. These have only two wings, and are furnished
with halteres, or poisers, instead· of under wings, as in the cammon
hO«Se fly, gnat, &c.
* This work contains two excellent plates, illustrative of the Distinctions of the Ordines and
Genera Insectorum, by their antcnare, tarsi of the fcet; &c. EDIT. .
•
E e 2

230
OF THE PUPA STATE OF INSECTS.
proceeds as if it knew what would be the result of its operations.
Difterent species prepare themselves for the change different ways,
suited to their nature and the length of time they are to remain
in this state.
'Vhen the caterpillar has attained to its full growth, and the
parts of'the -future butterfly are sufficiently formed beneath its
skin, it prepares for its change into the pupa state; it seeks for a
proper place in which to perform the important business: the
different methods employed by these little animals to secure this
state of rest, may be reduced to four:- 1. Some spin webs or
cones, in which they inclose themselves. 2. Others conceal
themselves in little cells, which they form under ground. 3. Some
suspend themsclves by their posterior extremity; 4. 'Vhile others
are suspended by a girdle that goes round their body. I shall
describe the variety in these, as ·weil as the industry used in constructing
them, after we have gone through the manner in which
the caterpillar prepares itself for, and passes through the pupa
state.
Preparatory to the change, it ceases to take any food, empties
itself of all the excrementitious matter that is contained in the
intestines, voiding at the same time the. membrane which served
as a lining to these . and the stomach. The intestinal canal is
composed of two principal tubes; the one iriserted into the othcr;
the external tube is compact and fleshy, the internal one is thin
and transparent; it is the inner tube, which lines the stomach
ancl intestiues, that is voicled with the excrement before the
cbange. It generaU y perseveres in a state of rest and inactivity
for several days, "\Yhich affords the external and internal organs.
that alie under the skin an opportunity of gradually unfolding
thcmsclvcs. In proportion as the change into the pupa form approaches,
the bod,y js observed often to extend and contract it-

OF THE Il\1AGO OU FLY STATE OF INSECTS, 23{)
scrved. Onc of thc most remarkable circumstances is, that the
circulation of this fluid in the moth is dircctly contrary to that
which took place in the caterpillar; in this, thc liquo1& move{l
_from the tail to tbe head, 'Yhereas in the moth, it moves from the
head to the tail; so that the fluid which answers the purposcs of
the blood in the moth, goes from thc superior, towards the i'nferior
parts, but in the voracious sensual caterpillar, the order is
invertcd, it proceeds from the inferior towards the superior parts;
all its members, formerly soft, inactive, and folded up under an
envelope, are expanded, strengthened, and exposcd to observa!"
tion.
The food of the caterpillar is gross ancl solid, and cven this it
is obliged to earn with much labour and danger; but, when freed
as it were from the jaws of death, and arrived at its perfect form,
the purest nectar is its potion, and the air its element. lt was
su pplied with coarse food, in the :first state, by the painful opera ..
tion of its teeth, which was afterwards digested by a violent trituration
of the stomach. The intestines are now formed in a
more delicate manner, and suited to a more pure MJ.d elegant
aliment, which nature has prepared for its use from· the most
fragrant and beautiful fiowers. J\lany internal parts of the cater­
:pillar disappear in the chrysalis, and many that could not be pereeived
before, are now rendered visible: the interior changes are
"not less surprizing than those of the exterior form, · and are, properly
speaking, creative of them; for it is from these the exterior ·
-form originates, and with these it always corresponds. In a word,
the creature that heretofore crept upon the earth, now ß.ies freely
through the air; and far fronl creating our aversion by its frightful
prickles and foul appearance, it attracts our notice by the most
elegant shape and apparel, and, from being scarce able to move .
from one shrub to_ another, acquires strength and agility to tower;
far above·the tallest inhabitant ·of the forest.

OF 'rHE GENERATION OF 'tNSECTS. 271
gated, • enabling one single individual to give birth to thousands,
or even millians of individuals like itself; all formed agreeablc to
proportians which are only known to that ADORAJ1L.E "\VISDOM
which hat; estaolished them. · 'V e shall never be able to form any
adequate conoeption of this l)ower, till we are acquainted with
the principles of life, and can trace their various gradations in
different orders of beings. l\Iany ancient philosophers, from a
misconception and perversion of the sentiments of the more an·
cient sages, imagined that insects were produced from corrupt
and putrefied substances; that organized bodies, animated with
life, and framed in a most wonderful manner, owed their origin
to mere chance! Not so the most ancient sages; they taught that
every degree of life must proceed from the fountain and source of
all life, and that therefore, '\Vhen manifested, it must be replete
with infinite wonders; but then they also shewed, that if in its
descent through the higher ()rders of being it was perverted, it
would be manifested in ]oathsoine forms, and wit:h filthy propen·
sities; and that accgrding to the degree of reception of the Divine·
Goodness and Truth, or the perversion thereof, new forms of life
would be occasionally manifested. The gloom of night still
wraps this'subject in obscurity; will the dawn of day ere long
gild the horizon of the scientific world? or is the time of its
breaking forth yet far from us? Ee this as it may, insects will be
found to conform tothat generallaw of order which runs through
the whoJe of animated nature, namely, that the conjunction of
the male and female is necessary for the production of their offspring.
WheFe we cannot ascertain causes, we must be content
with facts ..
• Though insects are, like larger animals, distinguished into male
and female, yet in some classes there is a kind of mules, partaking
of neither sex, though themselves originating from the conjunc ...
tion of both: many other particularities relative to the sexes calli
•

•
QP 'l'HE APHIDES. 277
ceed one another in the interval. One is produced in I\Iay, which
casts otf its covering; while the months of June and July each
supply two more, which cast otf their coverings three or four
tirnes, according to the different warmth of the season. This frequent
change of their outward coat is thc more extraordinary, because
it is repeated rnore often when thc insects corne the soonest
to their growth, which sometimes happens in ten days, where
warmth and plenty of nourishment conspirccl.
Early in the month of June, some of the third generation, which
were procluced about the rniddle of lVIay, after casting off their
last covering, discover four erect wings, much longer than their
bodies; and the sarne is obsvrvable in all the succeeding generations
which are produced during the summer months, but still
without any diversity of sex; for some time before the aphides
come to their full growth, it is easy to distinguish which will have
wings, by a remarkable fullness of the breast, which in the others
is hardly tobe disfinguished from the body. When the last covering
is rejected, 'the wings, which were before folded up in a
very narrow compass, are gradually extended in 0 a surprizing
manner, till their dimensions are at last very considerable.
The increase of these insects in the summer time is so very
great, that by wounding and exhausting the tender shoots, they
0
would frequently suppress all vegetation, had they not many
euernies to restrain them. Notwithstanding these insects have a
numerous tribe of eneinies, they are not without friends, if those
may be considered as such, who are officious in their attendance
for the good things they expect to reap thereby. The ant and
the bee are of this kind, collecting thc honey in' which the aphides
abound, but with this difference, that the ants are constant
visitors, tbe bee only when flowers are scarce; the ants will suck

PHALlEN A COSSUS. 337
first the word DIVISION is annexed. .The several parts exhibited
in the divisions, Fig. 1, are the musdes; those in. Fig. 2, undr.r
the word ring, are also musdes, which appear when those in
Fig. 1 are removed, 1 ying under them.
The anatomical delineation of the musdes of the head, Fig. 5
and 6, should be considered as consisting of two figures, which
join in the middle, being terminated by the superior and inferior
lines. The head, _as here represented, is magnified about threehundred
times. H H are the two palpi: the truncated musdes d,
belong to the lower lip, and form a part of those which give it
.motion: K, the two ganglions of the neck united: I I, the two
silk vessels: L, the oesophagus:. M, the two dissolving vessels: the
Hebrew letters denote the continuation of the cephalic arteries:
s T u w and x are the · ten abductor musdes qf the ja w: und er e e
and ff aie seen four 'occipital .mi.tsdes: a a, a nerve of the first
pair, belanging to the ganglion of the neck; b, a branch of this
nerve.
Fig. 7 is an outliJile of the head magnified considerabl y more than
in the last figure, exhibiting the nerves as seen from the under part.
Excepting in two or three instances, only one nerve of each
pair is shewn, as a greater number would have occasioned confusion.
The nerves of the first ganglion of the neck are designcd
by capital letters; those of the ganglion a, are distinguished by
Roman;letters; those of the small ganglion, by Greek characters;
and those of the frontal ganglion, except one, by numbers.
A GENERAL VIEW OF THE INTERIOR PARTS OF THE
CATERPILL-AR.
\
The MUSCLES have neither the exterior form, nor the colour
of those of larger animals. In their natural state they are soft,
u .u

414
TUBULARIA CAMPANULATA.
daily, and oftlieseoval bodies new animals are produced, exactly
similar to the parent.
· If. these minute bodies be eggs, they are of a singular kind,
being destitute of any covering, and are neither mem branaceous
nor ernstaceaus; we cannot with propriety say the young ones
are hatched from them; we can, however, perceive these oviform
bodies to unfold themselves gradually. The developement is
accomplished in a few minutes, and an animalculum appears like
the parent.
Trembley amassed a great number of these eggs, and carried
them from England with him:, keeping them quite dry; on putting
them into water, they gradually developed, and became as
perfect as the tubularia from which they proceeded.
There is a very great similarity in the construction of this little
creature and many of the marine polypes, who, like it, exist in
tubes of the same growth with themselves.
Fig. 32 represents three tubularire campanulatre or plumed polypes
very much magnifi.ed, namely, one, hfacddehgi, which
is o:ut.of its cell; eh, the oesophagus; fg, the stomach; af, the
rectum; ac dde, the plurne, consisting of the base ,a e,· which is
but little seen, · and the arms c d d, which proceed from the edges
of this base; a second polype, AB I, which is within its cell, and·
in which the skin containing the plume is reversed. The third
polype, s tu u, is a young one exhibited out of its cell; g o o,
threads which are fixed at one end to the intestines of the anima1,
by the other to the bottom of the cell, 1 k. -

[ 415 ]
C HA P. VIII.
OF THE ANIMALCULA INFUSORIA.
ÜUR knowledge of. the microscopic world is at present very
contracted, but we know enough to give us high conceptions of
its concealed wonders, and to iill us with profound astonishment
at the mftnite virlety ofrf()T.ÜJS;tha.t'are :made recipient of life ..
A few of the inhabitants oftbis :tninute world have been discovered.
The figure and apparent habits of life of these, resemble.
so little those with which we are tp.ore acquainted, that it is
often difficult to find terms to express what is represented. to the
eye.·
Animalculum signifies a little animal, and therefore the term
might be applied to every animal which is considerably inferior
in size to ourselves. It has been customary, however, to distinguish
by tne name of animalcula only such animals as are of a
size so diminutive, that their true :figure cannot be discerned
without the assistance of glasses; and more especially it ·is applied
to such as are altogether invisible to the naked eye, and can-not
even be perceived to exist, but by the aid of microscopes.
B y the hel p of magnifying glasses we are brought into a kindl
Qf new world; and numberless animals are discovercd, which,,

A METHODICAL DIVISION
reasonably conclude that it is from hence that the little eels issue
from the parent.
In the latter part of the year, and during the ·winter, tl1ese eel"
are oviparous, and the young eels may be seen to proceed from
the egg; at other times they are viviparous; six live eels have
been seen at one time in the belly of the parent, twenty-tw6
eggs have been counted in the ovary. ]\-füller suspected fhat
there was a difference of ,sex in some of these animalcula, but it
was left to M. Roffredi to afford the proof, and it was

•
OF THE ANIMALCULA INFUSORIA.
This animalculum is long, more convex than most of the gcnus,
divided by a kind of articulation into two parts equal in brea.dth,
but of different lengths, the fore-part being shortcr than the hindpart;
the apex furnished with short waving hair, indistinct rnole-'
cules withinside, no hair on the hind-part .
.
217. TRICHODA LINTER. T. ovato oblonga, utraquc cxtrcmitate
prominula. Plate XXV. Fjg. 51. The shape of an oblong
egg, with prominences at both extremities.
Both extremities of the body are raised, so that the bottom bccomes
convex, and the upper part clepressed like a boat. It varies
in shape at different ages, and sometimes has a rotatory motion.
It is foun,d in an infusion of old grass.
' 218. TfttEr1lÖDA PAXILLus. T. linearis depressa, antice trun-.
cata crihitaque, postice obtusa. Linear :Bat trichoda:, the fore-.
part truncated and hairy, the hinder-part obtuse.
A long animalculum, full of grey molecules; the fore-part ra, ...
ther smaller than the hind-part, and furnished with minute hairs.
It was found in salt water.
21Q. TRIGHODA. V ERMICULA.RIS. T. elongata, cylindracea,
collo brevi, apice cri!lito. Plate XXVII .. Fig. 1.. Long cylindrical
trichoda, with a short neck, the apex. hairy .
•
Gelatinous, the fore-part pellucid;the hind-part full of molecules.
It was found in river water. It is represented in different
appearances it;l. the ':fi.gure; a, the neck; b, the bairs; c, a
little vesicle in the hin'der.:part.

A DESCRIPTION OF MINUTE SHELLS. 033
or ornanient, or to the satisfying any appetite: neverthcless, a
much nobler idea wrill take its rise in our opinion; one which, by
displaying so momentously the power of the omniscient Creator,
wi-ll thwart the infidel in his favourite ideas of escaping the eyes
of the Almighty, and force him, as he descends the .scale from the
moreimmense objects to these minutissima, to confess, that the
being vvhich has formed these, can fully equal all that the tongue
of man has yet declared of the possibility of his power. For,
what a train of wonders have we here to pursue? 'Yhat must be
the reconomy of animals so very diminutive, so weak, so exposed
from their situation to the force of every rude wave, and who,
not\.vithstanding, so often escape unhurt? How do they rear their
young? From whence collect their prey ?"
A. DE$CRIPTION AND ARRANGEMENT OF MINUTE AND
RARE SHELLS.*
SERPULA.
TllE WORM-SHELL.
SERPULA BicoRNIS. Plate XIV. Fig. 2. S. bicornis ventricosa.
The bellied semilunar worm-shell.
The 'colour white, opake, and glossy. From Sand wich and
Reculver; though not common.
SERPULA PERFORA TA. Fig. 3. S. bicornis umbilico perforato.
The semilunar perforated worm-shell.
* Being possessed of Mr. Jacoo's own corrected copy of the work, to which he has annexed
the trivial names. I am thereby enabled to affix them to the several shells here enumerated.
I
4 L

08.02.2011
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