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LEEUWENHOEK (A. van). The select Works of
microscopical Discoveries in many of the Works of
Latin Editions, by S. Hoole.
3 parts in 2 vols, 4to., jvilli portrait and 22 folcliii
1798-1807 (^
First Edition. J^
S? i.
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THE
SELECT WORKS
OF
ANTONY VAN LEEUWENHOEK,
CONTAINING HIS
MICROSCOPICAL DISCOVERIES
IN MANY OF THE VVORKS OF NATURE.
TRANtLAT£D FROM THE DUTCH AND LATIK EDITIONS PUBLISHED BY THB AUTHOR,
By SAMUEL HOOLE.
VOLUME THE SECOND. PART THE THIRD.
^p Iprath aocft ban He baomen, ban Den CeUer=bcom aen
Die op Den ILibanan is, tot op Den gtop Die aen Den
toanDt iipt toast : i)p Qjracft oocft ban I)et Oee, enDe
ban i)et (Sebogelte, enDe ban De fttuppenDe Dieitn,
enDe ban De aifedjen.
3, liujninsen, ib. 33.
And he fpake of trees, from the cedar-tree that is in Lebanon,
even unto the hyffop that fpringeth out of the wall ; he
fpake alfo of beafts and of fowl, and of creeping things,
and of filhes.
I. Kings, iv. 33.
LONDON:
PRINTED BY THE PHILANTHROPIC SOCIETY,
And Sold by G. and W. Nicol, Bookfellers to His Majefty, Pall- Mall j J. White,
Fleet-Street ; and J. & A. Arch, Cornhill.
M,DCCC,Vn.
Oil the format'ton of the Elm, Beech, JVilloir, Alder, Ehony, Box,
and Lime-tree, tcith an explanation of the manner in ivhich Pipe-
staves for making Cafks are prepared from Oali-timber.
J. HE formation of the Elm is reprefented in Plate "Kl. fig. 1. AB
C D, and the fize of the piece of wood here magnified, when viewed
by the naked eye, is fliewn at letter E ; this figure alfo contains as
much as the tree encreafed in fize in the fpace of one year; AB
and C D, denote the places where, in autumn, the growth ceafed.
The fmall perpendicular or afcending vefl'els which lie in great
numbers intermixed among the large ones, are lets in this wood
than in the Oak, and moreover, each of thefe fmall tubes or veflels is
compofed of tougher and thicker membranes than thofe in the Oak.
At A B and C D are fliewn the horizontal vellels lying length-
wife.
Fig. 2, FFFF, exhibits the horizontal velTels cut tranfverfely ;
fuch of them as appear collecled in fmall parcels, I take to be thofe
which are beginning to be formed from the perpendicular veflels ;
and, that thofe which are collected together in great numbers, are
the produce of feveral years growth, and contain as great a number
as ever would be formed in the future growth of the tree.
G G G G, fliew the very fmall perpendicular veflels lengthwife.
H H reprefents one of the larger perpendicular veflels cut lengthwife
down the middle. Upon a moi'e accurate examination of thefe, we
fliall perceive them to be compofed of exceedingly thin membranes,
covered with filaments twifled in a ferpentine form, and having the
appearance of dark fpots and tubercles or rifings, as at^^. 3, B.
Among this fpecies of tree, we often fee fome, from which, at the
A
( 2 )
thick part of the ftem the rifing fap leaks or oozes out, and in this
liquor I have often, in the fummer time, obfcrved various animal-
cules, but which animalcules I could by no means conceive to have
illued from the wood; but rather, that the firft rudiments of them
had been depolited either by the rain or dew.
At fig. 4, ABCD, is pi(5lured a fmall particle of Beech, to the
naked eye appearing of the fize reprefented at F ; the length of this
figure alfo fliews the thicknefs acquired by the tree in one year's
growth, the beginning and ceallng of which growth plainly appear
at the letters A D or B C.
In this wood are two forts of perpendicular veflels, large and fmall
ones ; and, I am inclined to think, that there are alfo two forts of
horizontal ones, very minute, one fort of which appears at E E E,
lying in fmall numbers together, and when cut tranfverfely they
are fhewn in ^jg-. 5, at the letters H H H.
The other fort lie in detached parcels, and are fhewn lengthwife at
D C; thefe veflels are alfo very fmall in comparifon with the perpen-
dicular ones, and are compofed of large clufters colle6led together, a
reprefentation of them when cut tranfverfely may be feen irijig. 5,
at I I.
K K K K, are the large perpendicular vefl"els cut longitudinally;
and thele I have almoft always obfei-ved to be covered with par-
ticles which, viewed by a common magnifier, exhibited the appear-
ance of globules.
Fig. 0, ABC D, is a fmall piece of Willow, to the naked eye ap-
pearing of the fize fhewn at F ; this wood confifls of two forts of
perpendicular veflels, fmall and large ; the large ones are covered with
particles bearing the appearance of globules, and in thefe I obferved
Certain oblique flreaks, which I long ago concluded to be valves*:
* The author's opinion rcfpefting <he probable ufe of valves, in the veflels of trees
may be feen iu his Effay on the Oak, vol. I. p. 1
( 3 )
one of thefe is Ihewn in fg. 7, where the perpendicular veflels
are exhibited lengthwife, and it may be- feen in the veflel marked
G G. The Imall perpendicular veflels are compofed of exceffively
thin membranes, and thefe it was not in my power to reprefent
truly in a drawing.
In this wood I only obferved one fort of horizontal veflels, which
are lliewn lengthwife in Jig. 6, at E E E; the number of thefe is very
fmall, compared with the horizontal vellels I have obferved in other
woods.
Fig. 7, H H, reprefents them cut tranfverfely, and intermixed
with the perpendicular veflels, which in the fame figure apj)ear
lengthwife.
In one of the large perpendicular veflels reprefented in fig. 7, at
G G, I have fliewn the appearance they exhibit of being covered
with globules, but thofe .exceffively minute.
Fig. 8, is a particle of Alder, about the thicknefs, when viewed
with the naked eye, of an hog's briflle : this wood has too forts of
perpendicular veflels; the fmaller ones confifl; of exceffively thin
membranes, the larger of membranes covered with particles of
wonderful minutenefs, and to which no other figure can be affigned
than that of globules.
A B or C D denote the length of the tree's increafe in the Ipace
of one year; E E E E are the horizontal veflels.
Fig. 9, F F F F, are the large pei-pendicular velTels cut longitu-
dinally ; H H are the fmall perpendicular veflels : G G, are the
horizontal veflels, which here are feen cut tranfverfely.
Fig. 1 0, A B C D E F, is a fmall particle of Ebony, the growth
of the ifland Mauritius : this figure is drawn from a microscope,
magnifying objects much more than thofe from which the draw-
ings of the other woods were made, becaufe the veflels in this wood
could not be conveniently difcovered by a common magnifier. The
( -1 )
particle of wood here fliewn, in which are to be feen about eleven
hundred perpendicular veflels, is not larger than can be covered by
a common grain of fand. I did, at firll, delign to have made a
drawing of a larger portion of this wood, with intent to fliew the
decreafe of the growth in autumn, and its renewal in the fpring; but
on reflection I found that fuch an attempt would be fruitlefs, foraf-
much as this wood grew in a climate where vegetation never ceafes;
the ifland ISIauritius being lituated a few degrees to the north v/ard
of the Tropick of Capricorn.
In this wood there are four forts of perpendicular veflels ; G G G
are the largell of them ; fome of which feem to have had in them a
kind of fluid fubflance, which in drying coagulated in federal places,
as may be feen in Jig. 1 1 , at K K, where one of thefe largell veflels is
Ihewn cut longitudinally.
Fig. 12, is alfo one of thofe larger vefl'els (drawn from a micro-
fcope of flill greater magnifying power), much more tranfparent
than the former one, and likewife with inconceivably minute par-
ticles.
The fecond fort of perpendicular velTels, which generally are litu-
ated between the horizontal ones, are fliewn lengthwife at A B C
and H 11 ; thefe, in many places, feem partly filled with a black
fubflancc.
The third fort of perpendicular vefl^els lie in the fame direction
with the circvmiference of the tree, and are reprefented at B E or
CD.
The fourth fort of perpendicular veflels, w^hich are fliaped fome-
w hat like a lozenge, and are placed among the larger perpendicular
veflels, are compofed of a much more folid wood or fubflance than
the veflels in the other woods ; for the fmall round cavity which
appears in the face of each veflel, cut tranlverfely, as appears in the
figure, is the only aperture in each veflel, and the remainder of fuch
veflel furrounding this cavity is folid wood, conftituting the fub-
flance of the veflel ; and this fourth fort of veflels are fo clofely
( 5 )
compaL^ed and conjoined together, that they feem to be one fingle
piece of wood ; as if we were to figure in imagination a number of
fmall holes, bored in the moll exadl order and proportion, in a piece
of the hardeft wood.
Fig. 11, II, are the horizontal veflels cut tranfverfely : two
of thefe may be feen lengthwife, infg. lo, at the letters ABC and
H H. Fig. 11, LL, are the fmaller perpendicular veflels cut longi-
tudinall}^
Fig. 13, A BCD, is a very fmall piece of Box-wood, drawn from
the fame microfcope as the piece of Ebony before-defcribed ; and,
although I examined this wood veiy attentively, I could not perceive
in it any appearance of alteration in its texture, as refpedting or de-
noting the diiFerent feafons of the year in which it was produced ;
for which reafon I made a drawing of no more than one minute
particle, here reprefented. I found this wood to conllll: of two
forts of perpendicular or aflending veflels, namely, a larger fort and
a fmaller, intermixed with the larger.
The larger veflels are compofed of fine membranes, full of parti-
cles wonderfully minute, which are reprefented in Jig. 14, where the
larger veflels are fliewn, cut longitudinally, as denoted by the
letters EEEE.
The cavities of the fmall veflels are very much like to thofe
in the fmall veflels of the Ebony- wood, and thefe, when cut longitu-
dinally, are fhewn in Jig. 14, at FF.
A B, or C D, are the horizontal vefl!els, as they appear viewed
lengthwife, and cut tranfverfely, they are fliewn in Jig. 14, at GG.
I have often examined the Lime-tree, as well that which is
brought to us from Norway to be ufed in carving wooden figures,
as that which grows in this country; and, in order to fliew the
wonderful make of this wood, I have caufed a drawing to be made
( 6 )
of a fmall piece, as feen through the micro fcope ; this is fliewn tit jig.
15, HIKL.
All the parts of which this wood confifts, feem to me, to be
formed with a cavity in each of them ; and, if we refieA on the mi-
nutenefs of the perpendicular vellels and tubes which are to be {een
in this fmall piece of \\ ood, we cannot biit contemplate them with
admiration, as I myfclf have often done ; for the real lize of this
piece of wood, from K to L, is not more than five hairs breadth.
At H I, and alfo at K L, are fhewn the horizontal veflels in the
Lime-tree. I have obferved that, in fome places, they lie much
clofer together than here reprefented.
In jig. 1 0, A B G D, are fliewn fome of thofe veflels and woody
tubes of the Lime-tree, which, in the former figure, appear cut
tranfverfely, and are here fliewn longitudinally.
TO THE READER.
Among the different f pedes of tvood defcribcd hy Mr. Leeinvenhoeli ,
he makes no farther mention of the AJli than by laying dotim thej'ame
criterion to judge of its goodnefs as of the Oak. His tvords are as
follows :
" The Afli timber brought from Norway, which is very flow
in its growth, is of a very Ipongy texture, and confequently of
a weak and perifliable nature, and by no means to be compared to
the Afli which grows in thefe parts, and in a good foil ; b}^
reafon that this wood, as well as the Oak, at the firll of its
gro\\ th, every year forms very large veflels, and the reft of the year
much fmaller ones, confequently the quicker the growth, the fewer
of the larger, and the more of the fmaller veflels will be formed
within the fame fpace. I have examined many Norv^-ay Afli-trees,
and have obferved tliat, in the fpace of twenty, thirty, nay, forty
years, they had not acquired an inch in their femidiameter ; whereas
thofe growing in the neighbourhood of our town would encreafe an
inch in their femidiameter for many years fucceliivcly; and I conflder
( ^ )
Alli-timber, growing in warm climates, to be, beyond comparifon,
preferable to fuch as is produced in cold regions."
The Tranflator in resuming this part of the fuhjed, obferved a
paffage in the EJjfay on the Oak, tvhich had. fomehow efcaped him ;
he therefore takes leave to introduce it here.
As many perfons cannot conceive how calks made of Oak can con-
tain liquors, when they conlider that the wood is compofed of no-
thing but numbers of fmall tubes united, I cannot refrain from
giving an explanation of the manner in which Oak is prepared, and
worked up in the making of tubs or cafks, which is as follows : The
tree is fplit or cleft lengthwife into two, four, or fix pieces in pro-
portion to its fize, but fo that the fplitting or cleaving may extend
from the circumference to the centre of the tree ; though when
a tree is cleft in two, as I have feen performed in much of the
Riga timber, pieces are again cleft from the flat fides of each half,
making a fort of four fquare ftaves ; likewife, when large trees have
been thus cleft down the middle, planks or ftaves are made from
them, by cleaving pieces from that fide which was the middle of the
tree ; and thefe pieces will be four fquare and not triangular; by all
thefe methods of fplitting or cleaving the wood, the perpendicular,
and alfo the horizontal veflels will be divided lengthwife, or accord-
ing to the fame dire6lion in which they were placed in the tree, and
they will all lie lengthwife in the plank or flave, the perpendicular
veflels from end to end, and the horizontal ones from fide to fide,
by which means the liquor in a cafk or vat, made of timber thus
prepared, mufl prefs againft the fides of the veflels or tubes of the
wood ; and this is the reafon why cafks made of Oak, though it is
formed entirely of tubes, do yet retain the liquor; — to illullrate this
by an example :
( 8 )
LetAEFG, reprelent a piece of Oak timber, fplit or cleft
lengthwife into fix parts, one end of which is lawed tranf-
verfcly, and planed or fmoothed, as reprefented in the figure. Now
if this wood be cleft in fuch manner that A E, A F, or A B C D H
I G is made one fide of the Have, it follows that all the perpendicu-
lar veflels, and alfo the horizontal ones which extend from the
centre A to the circumference E F, and here are denoted by fixteen
double lines, mull be feparated from each other longitudinally,
A^■hereas, on the contrary, if the wood was to be cleft from E to-
wards G, then all the horizontal veflels would be cut tranfverfely,
and thus lying through the Itave with one of their orifices
opening in the cavity of the calk, and the other on the outfide, the
liquor would leak out. And this is the reafon, why if entire trees
are fawed into Haves, all thofe, except what are fawed out of the
middle of the tree, will fufFer the water to pafs through them,
efpecially if the prellure of the water be very great.
And confidering this, we are not to wonder that new built fhips
are fubjedl to leaks, for if the horizontal veflels have their orifices
both on the inlide and outfide of the planks, and thefe are not flop-
ped by fome kind of pitching or drefling, the water mufl leak
through.
Various ohfervations on the Herring.
X HAVE often reflected on the following circumftance attending
river fifli, namely, that where they have a plentiful fupply of food,
their inteftines are always covered with fat; and on the contrary I
have observed, that many fea fifh, fuch as Cod-filh, Haddocks, Plaice,
Flounders and the like, though they are plump and bulky, never have
any fat on their intellines: Herrings, however, do not come under
this defcription, for, not only their bowels are very fat, but their
whole bodies are fo much fo, that fometimes when they are cut, the
fat or oil follows the knife, efpecially at that time when the roes
begin to fwell, at which time they are called in this country Maat-
gens-Haringen.
After much turning this matter in my thoughts, I had a fancy to
know what is the food of this fifli, and for that purpofe I enquired
of many men, ufed to that fiihery, what food they generally found in
the llomachs of Herrings when firfl: caught, but the conflant an-
fwer I got from them was, that they never found any. At length
I met with a merchant who fits out fliips for the Herring fifliery,
and from him I learned, that in a certain tract of fea near the coast
of Scotland, Herrings are caught, in the llomachs of which are found
fome kind of fmall fiflies, but that thofe Herrings will not keep
long.
Not content with this, I determined to wait for the feafon, when
certain Herrings are brought to our town, which, as I have heard,
are caught in great numbers not far from Amfterdam, in that bay
or fea, which, among us, is called by the name of the Ziiydcr
Zee.*
* The Ziiyder Zee or Zudder Zee, a fmall Mediterranean fea between North Hollanti and
Fricfland, whence probably its name of Zuyder, or Southern fea, being fo fituated in refpcft
of North Holland. It is very fliallow, and by Sir William Temple in his remarks on the
United Provinces, fuppofed to have been formed by fome great inundation in the middle age,
or about the ninth century.
S
( 10 )
Thele Herrings being brought to our town for Hile about the mid-
dle of March, I dilfe^ted fix of them, and I found in that fubllance
which I took out of one of their ftomachs, three Hving worms, all of
the fame Ihape, and fomewhat thicker than an hair ; but, about
four hairs breadth diftance from their heads, their bodies, which
in that part were round, were about four times thicker.
This Herring had been dead at leall twenty-four hours before I
examined it, and perhaps thefe worms might have lived a long time,
if they had remained in the chyle and within the stomach.
Moreover, in thefe worms or animalcules, I faw a vein, bent in a
ferpentine form, and of a blackifh colour, lying the whole length of
the animal, and near this vein certain fmall round particles driven to
and fro with great fwiftnefs, affording me a very pleafant Ipectacle.
Another of the Herrings had nothing except a certain red matter
in its llomach, which, upon viewing it by the microfcope, I thought
I faw to confift of certain round particles, which were almoll ground
down by the aftion of the llomach ; and I faw that they had been
compofed of many veflels : this was alfo the appearance of the
white chyle which I took out of the ftomachs of all thefe Herrings.
Seeing thefe things, I did not wonder that fifhermen fliould im-
agine Herrings have no food in their ftomachs, becaufe Herrings
do, in my opinion, feed on fuch fmall fifties, that they cannot take
in fufticient quantities of them to diftend their ftomachs, as we fee
in other fifli; and hence it is faid, that Herrings have no food
within their llomachs.
Now, fince we find fo fmall a portion of food in the ftomachs of
Herrings, and yet that they are fo fat at the time, when, as I faid
before, their roes are yet very fmall, we muft conclude that Her-
rings are continually feeding, and that their food consists of fuch
minute fillies as efcape the eyes of the fifliermcn, whereas other
fiflies are accuftomed to cram their ftomaclis with larger fiflies, and
to fuch a degree, that fometimes they are diftcnded to a fifth or
lixth part of the fifli's own bulk ; and therefore it is, that the fiflies
( 11 )
they so fwallow, remain in their llomachs feveral days, until their
bones are by the procefs of digeftion fo comminuted, as to be fit
for admiffion into the inteftines.
Since then we fee, that Herrings have fo httle food at a time in their
ftomachs and inteftines, and yet become fo very fat, vs^hich I think
is owing to their taking abundance of nourifliment, we muft con-
clude, that there are more animalcules or minute fifties in the fea,
than has ever yet been thought of : and hence we are not to wonder
that Herrings are fometimes caught in one, and fometimes in another
part of the fea ; fometimes in the fliallows, and fometimes in the
deep water, according to the places where the fmall filhes on which
they feed do from time to time refort ; fo that, here I think, the
words of fcripture may be applied " Wherefoever the carcafe is,
there will the Eagles be gathered together."
About the end of March, fome more of the fame fort of Herrings
were brought to our town for fale ; feveral of thefe I opened, and
faw that their livers were as large in proportion to their fize as thofe
in other fifti, which livers were alfo provided with a gall-bladder ;
thefe Herrings were in that ftate, that many of them were deftitute
of roes. In examining the chyle which I took out, both from their
ftomachs and inteftines, I perceived no difference, except by obferv-
ing in fome of them a few round particles, which I deemed to be
eggs of fifli; and of this I was the more afl'ured when, upon breaking
the membrane in which thefe round particles were enclofed, and
which was very tough, I faw the contents to be of a fluid nature,
mixed with larger and fmaller globules. Several of thefe round
particles I feparated, as well as I could, from the chyle, and placed
befide them fome fingle grains, or eggs, which I had taken out of
the hard roes of other Herrings, and then I clearly found that thofe
globules which I had taken out of the ftomach and bowels, were
Herring's eggs ; whence, I concluded, that thofe Herrings which,
about this feafon, are fometimes caught in the Zuyder Zee. in such
quantities, that they are more than fufticient for confumption, will,
for want of other food, devour their own eggs or roes.
( 12 )
In the next place, I took out of the cavity of the belly of two
Herrings a white worm, about as thick' as a horfc-hair, whofe body,
at each end, efjjecially near the tail, was very thin and pointed.
This fpecies of worm I have found in the Itomach and bowels
of feveral kinds of filh. Thefe worms, I concluded, had forced
their way through the llomach or bowels, and thus had got into
the cavity of the belly, becaufe their bodies were of a very hard
texture.
The circumftance, that thefe worms fliould penetrate, through the
inteftines into the cavity of the belly, may feem wonderful to many
perfons, who cannot conceive how a woimd can be made by a
worm in any inteftine, and yet the chyle not run out of that wound
into the cavity of the belly. But it fliould be confidered that the
head of this worm (which is very fliarp), piercing through the
inteftine, would caufe little or no injury to the part, becaufe
neither the head or body make much of a cut or wound, and, there-
fore, the veflels in its paflage would only be ftretched afunder, and,
immediately after it had palled, clofe again.
A gentleman of my acquaintance, hearing me argue in this man-
ner, told me, that he kept, in an enclofed place at his houfe,
a parcel of hens, in order to fupply himfelf with eggs, and that his
maid fervants were accullomed to throw the fand andfweepingsof the
chambers into this place, without taking the trouble to pick out fuch
pins as might be in them, and that the hens, which were kept thus
Ihut up, finding no fmall ftones or pebbles to fwallow, as it is in their
nature to do, will pick up the pins. Thefe fowls are generally
killed in the winter-time ; and, my friend told me that, upon cut-
ting them up, himfelf and all his family, not excepting his men and
maid fervants, had feen feveral pins flicking in their breafls ; and
that, alfo, a pin was found which had come out from one of their
bodies through the breafl-bone ; and that another pin was found
in the bottom of the brealt, with its point downwards, flicking out
of the Ikin, lb that only the upper part of the pin remained between
( 13 )
the Ikin and flefli, and two pins ftuck to the flefh in the middle
of the llomach, which had penetrated through its coat ; and, within
the rtomach, were many pins mixed with the food, which, pro-
bably, if the fowls had remained alive, would have found a paf-
fage out in fome part or other. This being the cafe, it is no won-
der that a worm fhould find a palTage, not only into the cavity of
the llomach, but into other parts of the body.
On the 14th of April more Herrings were brought to market;
.when I obferved many eggs fcattered among them, fo that I con-
cluded for certain, that, at this time, moft Herrings depofite their
eggs or roes.
Again, I took feveral Herrings, and, from the appearance of
their intellines, I judged they had been longer out of the water
than thofe I formerly examined ; yet, in the intellines of one of
thefe, I faw a living worm.
Moreover, I took, out of the bowel of a male Herring, the foft
roe of which was grown to its fiill lize, feveral Herring's eggs,
which were in that part of the gut near its orifice ; from whence it
again appeared to me, that the fliell or membrane of thefe eggs is
fo tough and hard, that it cannot be digelled or dillblved, either in
the llomach or inteftines.
I alio found, in this intefline, many particles not of animal, but
vegetable fubllances, and, among them, a hollow piece of a rufli,
or fome fuch vegetable ; in which I could very plainly perceive,
the pores or tubes of which it was compofed, and alio fome exceed-
ingly fmall flat particles, alio confilling of tubes, joined together.
I likewife found feveral thin oblong particles, the formation of
which could not accurately be dillingiiilhed, they being impervious
to the light ; and, among other things, I faw the fliell of a fea-fnail,
not larger than a grain of fand, whole circumference was divided
into eiglit parts or joints. The fliell of this fnail was fo very
thin, that when the moillure it contained was evaporated, it
entirely loll its handfome Ihape. And thus it was manifell to me,
( ^» )
that Herrings not only iced on I'mall filhcs, and even on their
own eggs, but that, when ui-ged by hunger, they will I'wallow any
thing they meet with.
Sinee then we fee, that the fnialler filh, and elpeeially Herrings,
which take lb little fooil at a time, that it is the vulgar o])inion, be-
caule their Itoinaohs are not di (tended like thole ot" other lilh, that
they live entirely without food, do yet become very fat; when,
on the contrary, cod and other tilh, \\ hich fometimes have, at one
time, as many as six lliell-lilh in their llomachs, have, neverthelefs,
no particles of fat, either between the tlelli} parts, or in the intelt-
ines, except tlie liver: What, I alk, is the conclufion to be drawn
from hence ? Surely (with I'ubmiliion to better judgment), no other
than this : that thofe kind of tilh have no veins or velfels adapted
to fecrete tlie tat tVom the food which is digelled in the lU)mach
or intcllines, and much lefs any vcllels to fecrete tlie fat be-
tween the tlelhy parts.
But fmee cod, haddocks, and other filh of the like kind, are
deftitntc of velfels to leparate the particles of fat, and yet are ah\'ays
able to get a large liipply of food, fuch a quantity of nourilh-
ment is conveyed to the rielhv parts of their bodies, that they
become fo hard and dry (I mean at the time ^\ hen their roes tirll
begin to fwell, which is in the fummer), that they are quite inlipid
to the palate, and, tlierefore are laid to be out of lealbn, m hereas,
it Ihould more properly be laid, that they are tlien too much fed,
or have taken too much nourilhment ; but, when the roes in thefe
filh begin to incrcafe. fo that in a few weeks, they mull be depolited,
fo much of the nourilhment palfes into the roes that the hardnefs of
the flelhy parts is diminilhed, and then thofe lilh again become
talleful to the palate, and are, tlierefore, faid to be in feafon.
Now, as the larger lilh are fed and nourillied by devouring the
fmaller ones, I have often thought, m hether minute cod-lilhes, or
otl.er tilh, when firll come forth from the eggs, may not teed on
tliofe exceeding minute filhcs, or animalcules, \\hich are found in
( ir. )
incrediljlc quantities in all waters, and arc Co minute, that millions
of them are fcarcely equal to the flze of a grain of fand; and, when
we confider that the young fry of pearch, trout, jack, and the like,
when only a few days or weeks old, are always obfen^ed fwimming
llowly againft the llrcam, we may conclude, that it is with intent
the better to catch thofe very minute fiflies, or animalcules, which
are carried down the flrcam in the contrary direction, and to feed on
them, till they are of lufficient growth to prey on larger filh ; and,
if we do but obferve the very large eyes of thofe fmall fry, much
bigger in proportion than other parts of their bodies, we may form
a tolerable conje6lure, that in the firlt creation, they were appointed
to have fuch large eyes, for enabling them the better to difcover and
catch thofe minute fiflies which ferve them for prey.
I have formerly laid it down as a fa6t eltabliflied*, at Icall in my
opinion, that fiflies living in rivers or very deep waters, or fuch
waters as are always in motion, are not obnoxious to any decay or
difeafe, and never die of old age ; and now, to apply that idea to
the fubjcdl under confideration. I have examined the fcales of
Herrings, and I uniformly drew this conclusion, that all the Herrings
caught by our fifliermen were, as far as I could obfcne, barely a
year old; in confirmation of which opinion, upon infpcAing Her-
rings caught about the beginning of the month of June (which were
procured privately, or as it were by fl:calth, becaufc, by our laws,
Herrings are not then permitted to be taken), they being fometimes
lent to me as prefcnts, I always found them to be of a much fmaller
flze than thofe caught a month or two later; and [ have thought that
perhaps all Herrings caught in Ihe North Sea ifliied from the roes
or fpawn which had been depofited the preceding year. Now, if we
lay it down as a certain fact, that all the kinds of fifli to us known !
when they firfl; begin to lay their eggs or fpawn, are not a year old,
and that the greater part of thofe Herrings, which are found on
thefe coalls in any one year, dcpofite the eggs from whence ifluc all
* Sec vol. I. p. 71.
X
( 1(5 )
the Herrings caught in the fucceeding year, (for if it were not fo,
there wovild certainly be found in the Ihoal Ibme Herrings much
larger than others, as we may obferve in all kinds of fifli which have
fcales) ; we may from thence draw this conclufion, that when Her-
rings have depofited their fpawn, they do immediately, or in a very
lliort time afterwards, quit thefe feas, and never return thither.
About twenty years ago, I heard a llory of an uncommon large
Herring, which was to be feen in our town, and, for the novelty of
the thing, was given a prefent to a company of great perfonages at a
public dinner. This Herring, I think, very probably had wandered
from the flioal, or had by fome means been detained in our fea.
If then, we obferve that in the fea adjoining to us, no Herrings are
found which are more than a year old, and that they then entirely
quit our coafls, and none of them are caught the following year;
who can allign any other reafon for this, than that Herrings, when
grown large, require more food for their growth and fullenance than
thiey can get in our feas, and therefore they migrate, or refort to
thofe places where they find a greater or more folid fupply of food.
To conclude, the fecrets of Nature, refpefting filhes in the fea, as
well in regard to their resorting to certain places, as in their de-
parture from thence, cannot be investigated with any precifion : for
inftance, what fhall we fay of the filh called the Shad, (in Dutch
ElftJ, for thofe fifli, when the time of their propagation is at hand,
are found in our rivers ; but when that time is pall quit the rivers,
nor are ever afterwards, as far as I have been able to learn, caught in
the fea.
*
4-
Of the ant*.
In a Treatife, lately publillied in Germany, on Microfcopical lub-
jetts, the author has given drawings of the Ant and its egg, in the
latter of which, he has reprefented the young Ant within the egg,
though not more than an eighth part the iize of a full grown Ant :
but as thefe figures appeared to me, to be very inaccurately taken, I
determined to enter upon an inveftigation of the fubjeft myfelf.
Upon digging up an Ant's neft, in my garden, and examining the
eggs (as they are commonly called), I found them not only to be of
ditferent lizes, but alfo fome of the young Ants within them, were
of a white colour, and lay, as it were, motionlefs, until they arrived
at their full growth. Hereupon I began to form very different
ideas from the opinions hitherto entertained, refpcAing thefe crea-
tures ; and, I concluded, that the Ant, as well ;as the Weevil
and other minute animals (in thefe cold regions), does, in the winter
feafon, lie without motion, and does not take any nourifliment ; and
that the colledions of food which Ants are obferved to make, and
to heap together in their nefts, during the fummer feafon, is for no
other purpofe than to feed their young.
Thefe my fentiments may appear new and llrange to many ; but
how can we conceive the egg of any creature to be larger than the
hind part or belly of the animal from which it proceeds, and,
nofft
* Tiiis Kffay was written in the year 1G87. A3 the, .A"'hor hciein combats fome gcne«-ally
received opinions, refjiefting the Ant, the Tranflalor has given his own words, as nearly as
pofTible, and in the order in which they ftand, that the Reader may form his own opinion upon
the fubject. ' ' .
Vol. it. C
( IS )
that in time, it can become as large as the whole body of the parent,
before tlic yojing one comes forth, and that, when come to this
grow til, it Ihall not afterwards inercafe in fize ? Tliis, however,
if thefe are the real eggs, we nmll: conceive of the Ant ; but, whether
tlie fame takes place in any other creature I know not, nor have
ever oblervcd. In all probability thefe eggs, as they are called,
when tirit laid, are very fmall, and continually inercafe in fize; the
conclufiou is, that they mull conllantly receive fome kind of nourilli-
ment to caulc Ivich increafe; whence we may infer, that the collection
of food which Ants, in the fummer time carry to their nells, is, prin-
cipally, to feed their young. This, my opinion, I doubt not will be
greatly controverted, becaufe the yoxmg Ants lie incloled in a kind of
Ikin or membrane, and, confecpiently, it is difficult to conceive how
they can receive nourilhment from the father or mother, when thus
complotelv leparated from them. And yet it is llill more ditH-
cult to conceive, how an animal in the egg, and alfo the egg
itfelf, can daily grow larger, without receiving aity nourilliment.
I did indeed, at firll, imagine that the young Ant was com-
pletely formed in this egg ; but at length I rejedled that opinion,
determining to examine the truth of this matter, and, if poffible, to
difcover bv what means thefe eggs of the Ant do increafe in lize.
And, reconciling, tliat I could not be at a lofs for Ants' nells in
my garden, having bi^en formerly much infelled by them, I took
a fpade full of earth, mixed with Ants and their eggs, which I put
on a clean flicet of paper, and fat myfelf down before it, to examine
the Ants carefully, who are accuilomed, when their nefts are
diflurbed, to carry away their eggs. Many of thefe 1 took from
them, and obferved, that what moll of them were carrying was
no other than a young Ant, quite white, and without motion;
though in others of thefe Ants the white colour was tiu'ned to a red.
Others were white, and of an oblong Ihape ; and thefe I took to be
what are ufually called the Ants' eggs. Thefe laft were fmallcr
and fmaller, and fome of them no bigger than a common grain
( 10 )
of fund : but, at firft, I had beftowed my attention only on thofe
particles which I had taken from the Ants, conceiving them to be of
ufe to me in my enquiry.
To this end I had brought with me feveral new glafles, in which
I colleAed fome of each of the before mentioned forts, as flir as
I was able, and, as I had only my fpedlacles with me, but which
magnified objeds confiderably, I examined, after the Ants had
almoll all run away, the earth (which confilled of clay and land
mixed together), and found in it feveral very fmall white particles,
which, I concluded, had been left there by the Ants, mixed with
fome grains of fand.
Upon my retiu'n home, I examined all with the microfcope, and
found, that thofe which approached nearelt to the likenefs of Ants,
had not aflumed their perfe6l figure, though of the full fize of
an Ant ; and the only difference confifted in this, that they were
entirely white, and without any motion, and their claws and horns
lay difpofed in regular order, in like manner as we obferve in
caterpillars, previous to their change into flying infe6ls, thovigh
thefe, of which I am now fiicaking, were not inclofed in any mem-
brane. Thefe are, doubtlefs, what are generally called Ants' eggs.
Others of thefe white particles, which were alfo of the fize of an Ant,
and approached nearer the fliape of an egg (of which fort I found
many), I perceived to be fliort thick maggots, having in their
bodies a black fpot, which, probably, mofi: perfons would conclude
to be the young Ant within. Of thefe I carried many about with
me in my pocket, and obferved, that before their change ap-
proached, they purged ofFthis black matter, which was their excre-
ments. I faw fome of them, within twenty four hours, and others
within forty eight hours, put off their fkin, and change into a white
cryfalis.
Others of thefe particles, or eggs, were fmaller and fmaller, till
fome of them I found lefs than a grain of fand ; and, among the
fmalleft of the particles which I had taken from the Ants, or found
( ^0 )
among tlie earth of their neit, 1 dil'covered leveral eggs lb mi-
iiute. that I coukl not. with my naked eye, dillern \\ hat they wei-e.
One ot' theie egg-s I placed bet'ore the microtcope, and canted
a drawing to be made ot" it. which is Ihewn in Plate XlL.^o-.
1, ABC. And. to give an idea of tlie minutenefs of this egg, 1
mealiirod it by a rule divided into aliquot parts; and. I mutt fay,
that ninety of the diameiei-s. breadth or thicknefs of this egg,
w ould not amount to an inch in length.
Another egg I placed Ix^fore the microfcope, in which the maggot
was io far "rown. that with its head, it advanceii bevond the ihell
of the egg. This is to be feen at /r^. 2, DEF; in which figure,
E F denotes w hat had been a part of the yolk of the egg,
but \\ as now tranfparent. and only tilled with air.
The next dav alter 1 had turned up diis Ant's nelt, as before
mentioned, it rained verv hard, and the dav followino^, it was verv
fair weather; whereupon I v\ent to vifit the place, and found two
holes newlv made in the earth, and the Ants runninir in and
out. 1 took up a fpade full of the earth vN'here thefe holes were
made, and found ii\ it manv ei;c;s of the lame mimitenefs 1 have
jult mentioned : thefe I put into ditierent glailes. fome of which I
carried in luy pocket : and, in fome of them, after the fpace
of twenty four hours, 1 perceived tlie maggot to be pert'eclly
formed in the egg ; but. in the greater part of them. I found the
maggot imjH^rfcct, being dead, and the egg dried, with the Ihell con-
tracted. 1 caufed a drawing to be made, from the microfcope,
of one of thefe lait named eggs, becaule, in it, tlie limner could dil-
tingifuli all the parts of the nia2:got"s bod v. This is ihew n at
Jig.s,GHL
I alfo placed before tlie microfcope one of the maggots, which,
at the fame time, had crept out of the egg, and caufed a draw ing to
be made of it as it then appeared. At Jig. 4, K L M, is the head,
and M N K. the body of this maggot.
Upon aticutively obferving tliis maggot, I was mucli gratiiied ^^ ith
( ^1 )
the fight of an inceflant motion a})pcaring withui its head (and, if
I may be allowed the exprcfTion, in its brain), for this motion was
as regular as we can imagine, juft as if we were to fee the motion
of the lungs of any animal in rcfpiration.
Sometimes I faw one of thefe minute maggots open its mouth,
as if in quell of food, at the fame time producing a minute globule
of air at its mouth, which, palfing through the head, went into its
throat.
Moreover, I caufed one of thefe maggots to be drawn when fo far
grown, that its body was the tenth part of one full grown, and
which is reprefented at //^'. 5, OPQ R ; in which figure, PQ is the
head, and the retl the body. Thefe maggots, when young, lie in
a curved pollure, but, when almoll full grown, they aliunie u
llraight figure. This maggot was drawn from a microfcope, mag-
nifying objects much lefs than that from which the former figures
were taken ; from whence the minutenefs of thefe eggs may very
eafily be conceived. I could have given a drawing of a full grown
maggot from the microfcope, but I think it uTinecefTary, becaufe,
from the laft figure, we can eafily form a judgment of a maggot, of
the fame fiiape, when ten times larger.
I muft confefs, that I formerly thought no othcrwife than that
thofe maggots to which, hitherto (for want of knowing better, we
have given the name of Ants' eggs), as feen by the naked eye, were,
in reality, the eggs of the Ant, and that tiie black fpot which we fee
in their bodies was the minute young Ant, not yet brought into life.
But I cannot fufficiently \\onder, how any one can fufier his imagi-
nation fo to deceive him, as to fancy, when ufing a microfcope, that,
through it, he fees in this egg (as we call it) a young unformed
Ant. And not only fo, but to make a drawing reprefenting its body,
head, claws, and eyes; when, on the contrary, no perfon what-
ever can foe the leafl: appearance of any fuch in this maggot \\ hich,
hitherto, has been called the egg.
1 have feen fome of thefe maggots, while very fmall, to have the
( 22 )
dark Ipot before mentioned, and others much larger, and even per-
fectly formed, not to have the Icall appearance of it. And, to
invelligate the true nature of this dark fpot, which fome are fo timple
as to imagine is a young Ant, 1 opened the maggot, and faw moll
plainly that it was the animal's llomach, and that the darkifli appear-
ance was caufed by the food in the ftomach ; and, with regard to
thofe maggots which have not fuch a fpot, this is owing to the dif-
ferent kind of food brought to it by the parents. In this difl'ec-
tion I faw not only the ftomach, but the intellines adjoining to it,
which were filled with globular particles of a darkith colour.
How is it polTible for us to fee in a maggot (which we call an
egg) a very minute young creature ? for I have before faid, that the
whole and entire maggot is transformed into an Ant, faving only
its Ikin which is left behind; but this Ikin or cuticle is fo thin, that
it does not amount to an hundreth part of the maggot's fubtlance.
This maggot has on its body, except the belly, many hairs, and
is uncommonly lluggilh in its motions, fo that it is feldom feen even
to flretch itself out, or to contract its body, but it often moves its
head, and fometimes, though not often, opens its mouth. It is, in
a word, entirely unable to feek its food, and, as I may fay, lies im-
moveable in its netl, without ever changing its place, and there-
fore it is neceflary that the parent Ants, or fome others of the tribe,
iliould continually provide food and bring it to the yoimg ones.
This being the cafe, the commonly received opinion mull be done
away, refpecting the indullry of Ants in carrying provilions to their
nefls for the purpofe only of laying up a llock of food for winter ;
whereas on the contrary, the greateft part, and who can tell whether
or not the whole, is laid up for the maggots which proceed from
their eggs (and who cannot poliibly feed themfelves), and to pro-
vide them with nourilliment until they are of fulRcient growth to
put on the Ihape of Ants.
And, in like manner as I have faid, that the Weevil does not lay
many eggs at a time, like the Silkworm's moth, and the common
( 23 )
fly, fo it is with the Ant, which is a long Uved animal, and during
the whole fummer continues to lay its eggs (at leatl in my opinion),
and if lb, they mull be continually employed in providing food for
their young. And this is an innate impulfe or inllindl implanted
in them by Nature, for otherwife their young (which are maggots)
mull be llarved for want of food.
I am aware that what I have advanced, and thefe my obferva-
tions will be difputed by many, and the rather, as fo much has been
written of the induflry and forelight of Ants in laying up llore for
the winter, but this I do not at all regard. I freely Ipeak my fenti-
ments as they occur to me ; and I think it Ls not at all improbable
that Ants throughout the winter, and efpecially if the cold be very
fevcre, can live without nouriiliment, lying motionlefs under ground
as other fmall animals do in the open air, fuch as the flea, the
weevil and others. And if we do but obferve the Ant, when in
autumn they devour our grapes, and take notice, if it be cold, how
llowly they move, we may very well conclude that, when the cold
increafes they may be entirely ina6live during the middle of winter.
Some perfons would have us believe that Ants bite the human
fpecies, and that their bite is venomous : but this is what I could
never obferve; and it feems to me very plain, that the mouth of
an Ant is not made for any fuch purpofe, partly becaufe its pin-
cers, which are provided with points or teeth, and are lituated in
the fore part of the head at the opening of the mouth, cannot exert
fufficient force to penetrate through the external Ikin of our bodies,
and make any impreffion on the fenlitive cuticle ; for the pincers
are too fliort, and the teeth in them too many in number, for fo
fmall an animal to have the power of reaching with them the
fenfitive cuticle ; and in the next place, if we do but infped; all the
parts, of an Ant's mouth, when in motion, we fhall fee that they
are not of a nature calculated to do hurt to any animal.
I have often feen an Ant produce out of its mouth four oblong
particles ; but they arc provided with fmall joints like thofe in the
1
( 24 )
horns of the Ant, fo that the pincers or teeth of tliis anunal i'ecm
defigned for no other ufe then to grind its food, and alfo to drag the
provifions it coUeds for its young to the place where the young
maggots he. But I always obferved, and without any one inllance
to the contrary, that thel'e Ants have a fting which is placed, not in
the head, but in the hind part of their bodies, and, ifat any time, we
molell or hurt the Ant, it immediately puts forth its lling (which
at other times it keeps within its body), and continually endeavours
to ftrike, for it does nothing but bend its tail downwards, and in-
<;eflantly moves its rting in and out of its body.
This motion of the iHng, is fo natural to the Ant, that though
the hind part of its body be cut otf from the reft, the fting will
continue to move tor fome time. And the Ant not only gives us pain
merely by Hinging, but with the fting it emits a tranfparent liquid
\\ liich is tranfmitted to the end of the fting ; and, from this liquid,
I conceive the principal part of the pain proceeds, owing to the
Iharp faline particles it contains, and that from hence alfo proceed
thole humoiu-s or fwellings upon the Ikin which we experience on
beinjr ftunjr.
The fwellings or pimples which I experienced from the Ants, in
my preceding obfervations of their manner of generation, gave
me more pain than in my life before I had experienced from them.
For it is almoft tvventy years ago that, having been violently ftung
by Ants, I then, upon examination, difcovered that they carried a
fting in the hind parts of their bodies.
Although this liquid omitted by the Ant, is in vciy fmall quan-
tity, I tried all means 1 could devife to dilcover, if poffible, the kind
of particles it might contain, but I could obferve nothing, except that
this liquor (though very tranfparent and fluid), confilted of parts fo
fixed that it would not evaporate; in like manner as if it had been an
oil : in one place I fancied I faw fome particles lying, of the nature
of falts, with fome others, fo minute, that I could not afcribe to
them any particular fhape.
( 25 )
The lling of the Ant has not any aperture at its extremity, through
M'hich this noxious litjuid is emitted (as 1 have heretofore faid
is the cafe with the Scorpion), but it is provided with a cavity, or
groove, fimilar to what we fee in thofe inftruments ufed by failors
to wet their fails, in order to make them hold the more wind.
Through this groove, or channel, the Ant is able to emit the liquid,
and that as far as the exti-emity of the fting.
Upon my taking off this liquid from the fting, I found that
the animaFs fupply was not exhaulled ; for, when it drew in
the Iting, a frefli quantity of li(juid came again forth with it, and
this, not once, but fevcral different times. This gave me reafon to
guefs the caufe of an uncommonly large tumour I once had, in my
arm, from the flinging of an Ant, which was, that the Ant, having
crept up my fhirt lleeve on the infide, and there begun to fting ; be-
fore I could ftrip off my other clothes, as well as my fliirt, it
had ftung me, feveral times, fucceftively, from whence a large
quantity of that noxious liquid had been inje6led, cauling a larger
fwelling, and a greater degree of pain.
Fig. 6, B C D, reprefents the fting of the Ant. A B D E denote
part of the animal's tail, which is covered with hairs.
What I have here noted is, however, only to be imderftood of
the red coloured Ants, and thefe are the only fort of them which I
ever faw in my garden ; but, in other gardens, I obferved another
fpecies of Ants, of a blackifli colour, and fomewhat lefs in fize than
the red Ants, and not nearly of fo hardy a make ; for I could cafdy
comprefs or fqueeze the hinder parts of thefe Ants, which part of
the body, in the red Tones, was very hard. And, whereas I have
faid, that I always found the former Ants provided with a fting, I
coxdd not difcovcr any fting in thefe laft mentioned ones, although
I opened more than twenty five of them.
As to the maggots in the nefts of thefe black Ants, they did
not differ from thofe produced by tlie red Ants, except in being
fomewhat fmaller than the red, when full grown. And, wherca.
Vol. II. D
( 2fi )
the firil mentioned maggots changed into the form of a cryfalis
(of which I faw great numbers, lying among the maggots), I could
not, among thefe laft maggots, difcern a fmgle cryfahs ; but I faw,
among them, a great nvimber of what are called Ants' eggs, which,
at one end, had a black fpot. A parcel of thefe I brought home
with me ; and, upon opening them, I found, in fome of them,
a perfe6l Ant, of a colour inclining to black, in others of them, an
Ant quite perfeft, but white.
The Ihell, or covering of this Ant, did not appear to me,
to be either a membrane, or the Ikin of the maggot, which it
had ftripped off in undergoing its change, for it was quite fmooth,
and without any wrinkle. And, as I could not imagine how this
covering was formed about the Ant, I put fome of the moft perfe6l
maggots into a clean glafs; and, when they had been in it for two days,
I found them to differ much from the firft mentioned ones. For
thefe latter ones had begun to Ipin, as filk worms do, and, when the
thread was about as long as two hairs breadth, they faftened it, with
their mouths, to the threads they had already fpun (doubtlefs, by
means of fome glutinous matter proceeding out of their mouths) ;
and, in this fpinning, I did not perceive them move more than their
heads and the two joints of their body next the head : and, after two
days, they had proceeded fo far in their fpinning that the maggot,
within the cafe, was no longer to be difcerned. When thele
had remained in the glafs in my clofet, the fpace of four days, I ob-
ferved, that forne of the Ants in them had gained fo much ftrength
as to break through the web or cafe in which they lay, and
run about the glafs.
Hence it alfo appeared to me, that thefe latl maggots, in their
change into a cryliilis, or an Ant, not only at once aHlime all their
limbs, and the complete fhape of their bodies, but alfo that, after
this change, they never grow any larger, unlefs they undergo
a farther change, and become flying infeds. So that we fee the
error of thofe who fay, that, in what they call the eggs of Ants, they
( 27 )
can diftinguifli the young Ants when not peifedlly formed, and
which, in procefs of time, increafe in fize ; when, on the contrary,
no Ant, or rather its maggot, is inclofed in its web or cafe, until it
has attained its full lize.
This being fo, it appears, that the young Ant, whether a
maggot, a crj^fahs, or a maggot in its web or cafe, has, hitherto,
been improperly called by the name of an Ant's egg; for, in
like manner as we can, with no propriety, denominate the cone or
cafe wherein alllk worm is inclofed, a filk worm's egg, it is equally
improper to call the maggot, cryfalis, or the web of the mag-
got, wherein a young Ant is inclofed, an Ant's egg. For, upon
comparing the true fize of an egg, laid by the Ant, with that of the
web or cafe wherein the maggot, containing the young Ant, is
inclofed (and which is commonly called the Ant's egg), I will
venture to fay, that nearly an hundred and feventy five Ants' eggs
do not more than equal the lize of the web or cafe fpun by
the maggot, and in which it is changed into an Ant.
I have before faid, that, at one end of the web or cafe fpun
by the young Ant, there is a black fpot, which, upon examination,
I judged to be the excrement of the maggot, and which it purged
off when it was about being changed into an Ant.
This web or cafe, fpun by the maggot, is of fo clofe a texture
that one can feldom difcern the Ant within it, unlefs when it is fo
far advanced in its growth that it begins to aflume a black colour,
or v/hen it moves itfelf within the covering or cafe.
In all the Ants' nefls that I have examined, I have obferved
fome of the Ants to have wings ; but in none of the nefts have I been
able to find the leaft traces of the provilions which they are faid to
ilore up ; fo that I am Hill more allured that, in the fummer feafon,
the Ants have enough to do to colleft and carry into their nefls
a fufficient quantity of food for the fupport and nourilhment of the
multitudes of their maggots, both great and fmall, with which
their nefls are, in many places, quite filled.
( 28 )
Moreover, about the middle of the month of Auguft, I examined
ieveral black Ants' nefts on the Lands we call Duynen or the Downs,
as well in the neighbourhood of Haerlem, as elfewhere, but I did
not find in them any of the maggots from which thefe Ants were
bred, nor any of the wobs fpun by them, but only fome empty webs
or cafes, out of which the Ants had crept.
I have alfo feen, in fome nefts, the greateft part of the Ants
changed into flying animals ; and, among thefe winged Ants, fome
were eight times larger than the common black Ant.
I, afterwards, again examined the nefts of the red Ants in
my garden, and found in them Ants, with their eggs, the maggots,
and cryfales, in as great numbers as before.
I alfo placed feveral grains of wheat before the Ants' nefts,
thinking they would not have ftrength to carry them away, but
I did not obferve them at all difpofed to touch the wheat, and they
only carried into their nefts a fmall barley-corn.
I have thus in my refearches difcovered two fpecies of Ants ; and
doubtlefs there may be many other fpecies of them in thefe parts,
which have not come under my obfervation. As to what forts of
Ants are found in other countries, \^'hich are much larger than rurs,
and what may regard their coUeAing provifions, and the nature of
their domeftic ceconomy, all thefe things are unknown to me.
Thefe are my obfervations (fuchas they are), refpe^ting the Ants,
from which I have colledled, and fatisfied myfelf of, the following
particxilars : Firli, that Ants lay very minute eggs ; fecondly, that
from thofe eggs maggots are produced, which are fed by the Ants;
and that the food which Ants are continually carrying to their nefts
in the fummer time, is for no other ufe than the nourilhment of
thofe maggots : and thirdly, that what people call Ants' eggs are
either maggots, crylales, or the v\ ebs fpun by the maggots, (with
maggots in the infide).
To fliew the true fize of our Ants, T caufcd a drawing to be made
of fome of the red ones, which is exprcftcd at^o-. -. '
( 2Q )
After this, being aboixt two hours' journey from our town of Delft,
and going into a plantation, belonging to a gentleman's houfe, a
working man fliewed me feveral Ants' nells, namely, fome of the
red Ants of the fame fize with thofe in my garden, in which I found
a great number of eggs and maggots of different lizcs, and many
cryfales among them ; alfo, fome nells of black Ants, which ap-
peared to be propagated in the fame manner as I have before def-
cribed refpedling them. But in thefe black Ants' nells, I found no
eggs nor maggots, except fome maggots employed in fpinning their
cafes, and fome cryfales in the cafes or webs. I alfo here found
a third fort of Ants, of a bright yellow colour; thefe were as fmall as
the black Ants, and in them I could not difcover any fting. The
maggots that came out of the eggs of thefe Ants, when brought to
their full growth, changed into Ants without Ipinning a web, in like
manner as I have faid of the red Ants.
For my ftill farther fatisfadion, I took out of my garden two
feveral Ants' nefts, and the earth which contained the moll: Ants,
with their eggs, maggots, and cryfales mixed ; thefe I put into a
glafs about nine inches deep, and eight inches in circumference,
on which I put a glafs cover, and gave the Ants for food fome
fugar, a piece of a pear, and fome cherries • placing the glafs upon
my delk, in order, if poffible, to difcover the manner in which the
Ants fed their maggots ; but thefe the Ants carried away, and con-
cealed under the earth in the bcft manner they w'ere able, lb that I
could get a light of but few of them at a time. But, upon obferv-
ing how motionlefs the maggots lay, I law, that though lliaken
about or carried by the Ants from place to place, or whether lying
in heaps or fingly, and no Ants near them, they did not llir them-
felves in the leall.
And as I frequently faw an Ant with its mouth clofe to the head
or mouth of a maggot, and in that pollure lie motionlefs for a time,
I confidered that probably one or more of tlie organs which the
Ant has in its mouth, might be formed for no other end than to
4
( 30 )
pill into the mouth of the maggots the food provided for them
bv the parents, which is what in beafts we name fuckhng.
From tliefe my obfervations, I concluded that probably the food
which \^'e fee the Ants in thefe countries carry to their netls, is what
thcv, for the time, have more than they can take into their llomachs,
and that they hide it in holes and corners in their nclls, luitil they
have fed their young with the nutriment prepared in their llomachs,
and this being done, they refort to the provifions they have brought;
which being prepared in their bodies to become nourilliment for
their young, they can immediately, \\ ithout quitting their nells,
fupply the yoimg maggots with more food.
Addition, by the Translator.
Mr. Leeuwenhoek having in this Effay noticed particularly, the erroneous
figure given by a German author, of what he calls the Ant's egg ; that
iiaure taken from Mr. Lceuwcnhock's copy of it, is here fubjoined : the
Trandator not chafing to infert it in the Folio Plate, left it Ihould, at firft
fight, be miflaken for a drawing given by our Author, with the accuracy of
whofe figures this is altogether incongruous.
Of a certain poifonous Reptile, common in the Eajl Indies, called in
Latin, Millepeda Indica, in Dutch, Duyfent-becn, and in English
vulgaris/ named the thoufand legs.*
1 HAVE often heard mention made of the poifonous pundure or
bite of a certain noxious animal in the Eall Indies, called a Mille-
peda, or thoufand legs ; this animal, as I have been told, creeps over
the bodies of perfons afleep, and being of a very cold nature, the
perfon is induced by the unufual fenfation to move ; if the perfon
does not llir, the animal pafles aw^ay without doing him any injury,
but if he moves, it bites him with the tM^o fangs or teeth, placed in
the fore part of its head ; and although no blood follows the bite,
but only a very fmall red or livid fpot appears, yet an intolerable
pain, with a fwelling, enfues, which remains longer with fome per-
fons than others ; and, to relieve this pain, the moll approved reme-
dy is, to drown the animal in oil of Olives, and to anoint the
wounded part with the oil.
Being defirous to fee one of thefe creatures, I gave in charge to
fome labourers employed in this town to unload the Eaft India
lliips, to bring to me a living Millepeda, in order that I might if
polTible difcover from what caufe the poifon in its bite proceeded ;
and thereupon they brought me one, about the fize of my little
finger, (though fome of thefe are two or three fingers' length). I
immediately took hold of it \Y\ih. a fmall pair of pincers, near one
of its two fangs or piercers, and examined the fang by the micro-
fcope, and all the while, the animal was continually opening and
fliuttings its fangs, as endeavouring to bite. I faw that in each of
* We have in England an animal probably of this fpeeics, though not venomous, and of
much fmaller dimenfions, to which the name of thoufand Icgsisgiren, particularly by cliil-
dren. It is often found under ftones or rubbifli : it is feldom toovc two or three inches long,
but in fliapc exaftly fimilar to the Milloiieda here dcfcribed ; and wonderfully nimble in its
IllOtJOIl?.
( 32 )
thcfe fangs, there was a round liolc placed in a kind of groove or
furrow leading towards the point, the intent of fucli furrow bcnng,
as 1 conceive, to convey fome kind of liquid ilfuing from the hole
to the very point of the fang, while it is within the part wounded ;
and hence, I imagine, that tlie Millepeda by its bite, wounds and
tears open fome of the blood vellels, or other vellcls w itliin the
Ikin, and at the fame time infufes a liquid into the wounded part,
which liquid, I fuppofe, contains fome noxious and very pungent
fait, and that the pain felt is not occafioned by the mere bite, but
from that noxious or pungent liquid. I did intend to liave purfued
mv obfervatious llill farther, and hatl delii'ed the labourers to brincr
me mere of thofe animals, but none Mere then to be had ; for
though feveral were feen in the fliip while the goods were unloading,
tiiey had been all killed upon the fpot.
The forceps, fang, or v\ hat may be called the lling of this Mille-
peda, I prefervcd, and caufed a drawing to be made of it. Fig. 8,
A B C D E F, reprefents a part of this forceps or tHng, as feen through
the microfcope. At C is to be feen the furrow or channel, and alfo
the liole in it, througli ■which this noxious animal, in wounding a
man, injedls the poifonous liquor.
After this, I was prefented by a certain gentleman who is. fond of
collecling all forts of foreign animals, with a large Indian INIillepeda,
ot which I have alio caufed a drawing to be made, becaufe many
perfons know nothing of this poifonous creature : this is fliewn at
jig- Oj G H 1 K L, and in this figure, I K, are the two fangs or Itmgs,
one of which is exhibited in the former figure, as (ccn through the
microfcope.
4i
Of the flea.
JjEING defirous to know how long time was requiflte for the egg
of a Flea to produce a perfect Flea, I fat about making experiments
to afcertain that fact ; but it was not till after many trials that I
could make a regular feries of fuccefsful obfervations.
In the month of July, I enclofed feveral Fleas in a glafs, that
they might lay their eggs ; the worms or maggots hatched from
their eggs, I nurfed with all the care I was able, feeding them
every day with flies, which I firft killed ; thefe they devoured with
great avidity, and thereby were very fpeedily increafed in lize. My
obfervations on this fubject are as follows :
On the 0th of July the worm came out of the egg.
On the 17th of July the worm appeared all over white, from
whence I concluded that it was near dying ; I twice offered it frelh
flies for food, but it would not eat, and appeared to me to be mo-
tionlefs, but viewing it with the microfcope, I faw that it was
employed in fpinning round itfelf a web or covering.
The 21st of July, this worm was changed into an aurelia or
chryfalis, which was of a tranfparent white.
The 25 th of July, this chryfalis aflumed fomewhat of a red colour,
which continually grew deeper and deeper.
The 30th of July in the morning, it was entirely red, and in
the evening the Flea it contained was leaping about the glafs.
Hereby we fee that in the middle of the fummer, in four days
time after an egg is laid by the Flea, it produces a worm or mag-
got, which in eleven days attains to its full growth, in four days
time it is changed into a chrysalis, and in nine days more it becomes
a perfect Flea.
Now if we lay it down, that it is with these creatttres, as \\ ith
moft fmall animals, which in like manner undergo a change, (at
YoL. II. E
( 34 )
leallas far as I know) that their eggs are formed in their bodies be-
fore they come out of their aureha thite ; it will follow, that Fleas
immediately upon their coming forth into life out of their webs,
can copulate, and in three or four days time lay eggs, fo that in
the fpacc of twenty-eight days, from a newly laid egg, a Flea may
be produced. This being the cafe, it is no wonder that in the
fummer we at fomc times perceive no Fleas in our houfes, and at
other times they appear in great numbers without being brought from
elfewhere ; and if we alfo fuppofe, as I am "VN'ell allured is the cafe,
that Fleas, after they have copulated and laid the eggs which they
had within them, do then die, we may conclude that we are not
tormented for a long time by one and the fame Flea.
But whereas many flying infects do, within a few fucceffive
days, lay all their eggs, <his is not the cafe with Fleas ; for a Flea,
which in one day or night laid 4, 5, 6, 7, 8, and even 12 eggs,
being afterwards fhut up in a glafs laid no more, though upon
opening it, I found in its body many eggs remaining, fome of
which were exceedingly fmall, whence I concluded that a Flea
being fo fhut up, its laying no more eggs was occafioned only by
want of food. To fatisfy myfelf in this respect, I took feveral
female Fleas, after they had laid their firft parcel of eggs, and
contrived to confine them on my hand, In order that they might
thence get a fupply of nourifliment : one of thefe fucked the blood
with great avidity, standing as it were \ipon its head, and lifting
up its hintler and middle feet with a quivering motion in them,
this Flea the following day laid two or three eggs, and two or three
days fucceirively afterwards, I placed it again on my hand, that it
might get a further fupply of food, but in vain, for it did nothing
but leap about and endeavour to efcape. The like happened to me
in feveral other trials I made, but if the Fleas would have con-
tinually fed on my arm or hand, I would have done my befl to
ascertain what is the natural term of this creature's hie.
On this occafion I cannot but obfervc that we meet with many
( 35 )
men who fet themfclves in oppofition to all new difcoveries, being
riveted to old opinions ; yet are themfelves too indolent to in-
vestigate the fubject, and the rather, as thefe refearches into
Nature's works are often very troublefome, and bring no gain or
profit. I ftiould endeavour to confute fuch opponents, did I not
think it would be loft labour ; and, indeed, I know not who
would bestow fo much labour as I have done on that minute and
despifed creature the Flea.
During the fpace of two months and upwards, I put into the
hands of my maid-fervant four or more glafles, with cork ftoppers,
and directed her to confine in them as many as fhe could catch of
the largeft fort of Fleas, which are always females, with a caution
to handle them gently, that none of the veins or vellels in their
bodies might be injured ; and thefe Fleas I frequently removed into
frefh glafles, to preferve the eggs they laid from being foiled with
the excrements they voided, in which, by the way I have plainly
feen a great quantity of faline particles. Now, if, as has been
obferved above, in tvs'enty-four days a perfect Flea is produced from
an egg, we fee that in a fingle fummer, or rather from the month
of March to November, Fleas may be propagated feven or eight
times, and fo often may we be infefted by new generations of
them.
Not content with the preceding obfervations, I at feveral times
trained up or nurfed the worms from the Fleas' eggs, till they grew
to their full fize, and I found that an egg in three days time pro-
duced a worm or maggot, and the worms or maggots in twelve or
thirteen days, or little more, came to their full fize. In particular,
about the middle of Auguft, I had two maggots, one of which
came out of its egg about two hours before the other : the firft of
thefe I glued to the point of a fmall brafs pin, and placing it before
the microfcope, I gave it into the limner's hand, directing him to
make a drawing of it, as nearly as he was able, for the worm
moved itfelf about violently.
E2
( 36 )
Plate Xll. Jig. 10, A B C exhibit this worm or maggots as glued
to the pin, and appears to the view as if it lay on its back. A is
the head, on which are two prominent parts, like horns, out of
which proceed two other Iharp weapons, fo fmall that the limner
did not perceive them until they were pointed out to him : between
thefe horns appear two fliorter prominent parts, which are not
placed on the head, but at the lower part of it, where the mouth
is Htuated : thele parts the maggot ufes in moving from place to
place, and alfo thofe parts at the hind 2>art of its body, which are
pictured at C.
After this drawing was made, the worm ftruggled fo violently,
that it got loofe from the glue, and in fixing it again on the pin, I
happened to touch its head with fome of the glue, whereby it was
much hurt, and after remaining fixed for fix hours, it died, foon
after which I perceived the moiflure of its body lb much evapo-
rated, that it was contracted into many wrinkles, and at the end
of twenty-four hours it was fo dried as to loofe all likenefs of a
maggot, whereas the other which was hatched two hours later,
and had remained fixed before the microfcope only two hours
lefs, was not only alive, but its body as fully dillended as if it had
been newly hatched.
After this M'^orm had been thirty hours before the microfcope
and was ftill very lively, I thought I faw its body not fo com-
pletely filled out, and confequently that fome of its moifliure was
evaporated. I frequently afterwards infpe6led it, and at the end
of fixty-four hours, I faw it fiill in motion, but its body diminifhed
in fize : this day the fun llione very hot.
At the expiration of four days and nights this worm was Hill in
motion. I did not examine it again till fixteen hours afterwards,
and its body was then much contradled : the following morning the
moifture of it was fo evaporated, that it could not be known to be
a worm.
This circumstance, namely, that in Jiving creatures there is fo
( 37 )
little wafte of moiftvire, I have obferved, not only in this maggoty
but in many minute animals, and even in the eggs of fmall infers,
(among which I reckon thofe of the flea) ; for if the fruitful and
barren eggs are placed befide each other, we thall fee the barren
ones dry away, whereas the fruitful ones will retain their moisture,
at leaft, fo far as to afford the maggot in the egg sufficient for its
nourifhment.
But what fliall we fay, when we obferve that the evaporation of
the moifture in fmall living creatures, or their eggs, is fo little, info-
much, that a Flea fhall remain wrapt up in the web or cafe it fpins
for fovTr entire months, and yet its moiflure not evaporate fo
far as to caufe its death ; whereas the moifture exhales from the
body of a dead flea in fo fliort a fpace of time. In a word, we
cannot but wonder at thefe appearances, and here our reflexions
muft tei'minate.
Before this worm, I have laft mentioned, came out of its egg, I
placed the egg before the raicrofcope, and caufed a drawing to be
made of it, becaufe I could not only fee the worm alive in the egg,
and how its body was placed, but I could alfo difcern through the
ftiell, many of the joints in its body.
Fig. 11. D E represents the egg of the Flea with the worm or
maggot in it, and which egg had been laid but three days. Fig. 12,
F G, is the egg from which the maggot had crept out, and in which
may be feen the manner how it had broke open the fhell. These
eggs of the Flea are no larger when viewed by the naked eye, than
fmall grains of fand : and as objects do not appear of the fame llze
to the eyes of every one, fo it was with the limner who made this
drawing ; for the breadth of this egg appeared to me twice the fize
here reprefented, and the worm alfo in the same proportion. I
could, however, if neceilary, have made drawings of thefe objeds
from microfcopes of greater magnifying powers.
After the preceding remarks, I fo far fucceeded in the treatment
( 38 )
of feveral worms or maggots, that I had two which acquired their
compleat portions of nouriihment, and began to fpin their webs; but,
becaufe the bottom of the glafs wherein they lay was flopped with
a fmooth piece of cork, and that prefTcd in fo tight that they could
not penetrate it, they could not completely cover themfelves with
the web. For in like manner as filk worms are placed in a paper
of a round tapering form, called a cup, in order that it may fix its
web on every fide, and be completely covered by it ; fo the worm
produced from the Flea's egg, when come to its full fizc, endea-
vours to creep into cracks, holes, or corners, in order to inclofe it-
felf on every fide with its web.
At feveral times I contrived to prevent the maggots enclofing
themfelves completely in their webs, in order that I might the more
eafily difcern their alteration into a chryfalis or aurelia. But how
often foever I viewed them after they had ceafed eating, and their
change approached, I could only perceive that they placed them-
felves in the fame pofition as they had lain in the egg. But exa-
mining them in the afternoon in this porture, I found upon look-
ing at them three hours afterwards, that one of them was changed
into a chryfalis. Upon viewing another of them through the mi-
crolcope, I perceived a mite upon its body, where it remained fome
time, and another larger mite running about the glafs, whereupon
I concluded, that at the time thofe worms are in their rtate of
change and unable to defend themfelves, the mites will feize and
feed upon them. After this worm had thus laid for fome hours, I
faw that its body was somewhat contracted, whereupon placing it
before the microfcope, I perceived three holes pierced in its body,
part of its Ikin llripped otf, and the body of it beginning to dry
away.
Hereupon I began to confider, that this web or covering fpun by
the Flea's worm or maggot is necessary to it, and that without it,
thofe creatures could not eafily be propagated ; for there are fel-
dom any fragments of food, or the bodies of fmall animals lyinf
( 39 )
about our houfes, but they are immediately found out by mites who
come to feed upon them ; and, in the prefent cafe, though I thought
I had perfe6lly fecured thefe maggots from the mites, becaufe the
glafs tube wherein I had put them, which was ahnoll an inch in dia-
meter, and five inches long, was fo clofely Hopped at each end with
cork, that I fliould have thought it impoffible for any mite to get
in ; yet now I found the contrary to be the cafe : and indeed, I
have often found mites feeding on things in places where I won-
dered they could fo foon discover their food. And now, upon
feeing thefe mites about the maggots, it occurred to my thoughts,
whether or no thofe fmall and very flender prominent parts in the
maggot, which m Jig. 10, are Ihewn at A, might not be weapons
designed for its defence againft the mite.
But the web fpun by the maggot, and wherein it inclofes itfelf,
before its transformation, proted:s it in that Hate from all attacks of
the mite ; and the like we may conclude, to be the cafe with the
filk worm, which while in its Hate of tranfmutation into a butter-
fly, is protected by its cone or cafe, not from mites, but from
birds ; and this I am well allured is the cafe with all caterpillars,
which when of full growth, and the time of their tranfmutation
approaches, do inclofe themfelves in fome kind of web, or co-
vering.
The maggot which I have faid I faw changed into a chryfalis, I
the next morning placed before a microfcope, and delivered it to
the limner, to make a drawing of it.
Fig. 13, A B C D E F, is this chryfalis ; A K, are the horns of the
yet unformed Flea ; L G B, is one of its fore legs, which rife out
of the head at L ; and herein, at B, may be feen all the Imall
joints which will be found in the legs and feet when perfectly
formed : the like joints may alfo be feen in C and D.
H C is one of the middle feet, and at G may be ieen that the
fore feet partly cover the middle feet, and thefe in part cover the
hind feet ; I D and C H are the two hind feet, which are in part
covered by the middle ones.
( 40 )
Fig. 14, MNO PQ, reprefent the pellicle put off by the mag-
got, when it changed into a chr^'falis, leaving the wrinkles in it as
they here appear ; and at M are the places where the maggot's
horns flood.
Three days after this drawing had been made, I faw that the
•chryfalis was very much altered, and many parts appeared in it which
till then could not at all be diftinguilhed ; therefore I caufed a draw-
ing to be made of this alfo, to Ihew fuch alteration.
Fig. 15, A S T V, is this drawing, taken as exactly as the limner
was able to reprefent this fecond appearance of the chryfalis.
Fig. 16, ABCDEFGHIKLMN, reprefents an entire Flea,
glued by tlie back to the point of a needle, and fo placed before
the microfcope, but being tirll killed, becaufe it would be impoffible
to make a drawing of a Flea while alive. Nor, indeed, did I intend
to have given a drawing of the whole Flea, but a certain learned
gentleman ftrongly urged me to it, faying, that the world would
thereby be more convinced, that Fleas arc not produced from cor-
ruption, but in the ordinary way of generation, and I therefore
complied with his request. In this animal a great number of blood
vessels were to he seen, particularly in the belly, but the limner
only drew a few of them, faying, that it was not in his power to
imitate the remainder in his drawing.
This Flea appeared to me, through the fame microfcope, eight
times larger than here lliewn, though the limner declared that it
did not feem any larger to him. Nor could I ever have believed
that there was fuch a diverfity in the fight of different people as I
now find to be the cafe. But this limner was very fliort fighted.
At D E F are fhewn the hind feet ; F G H the middle feet ; and
1 KL the fore feet ; placed on the head : and between thefe lie the
organs or weapons witli which the Flea pierces or bites, and feeks
its food. L M N are two horns on the Flea's head.
I had formerly figured to myfelf the manner in which Fleas must
.get their food out of the bodies of men and animals ; but becaufe
( 41 )
thofe parts in a Flea which I heretofore took to be the piercers or
weapons by which it draws the blood, appeared now to be the
flieath or cafe of the real piercers, which divide into two parts when
the Flea thrurts out its piercers from between tliem. I will now
defcribe how thefe parts appeared to me upon the examination of
three feveral Fleas.
Fig. 17, ABC are the two horns on the head, which have been
fliewn in the laft figure, each of them has three joints, befides the
joint fixed to the head ; D E is the fheath or cafe, with the llings
or piercers, which in a manner fit or lock into each other, as I ob-
fei-ved while I was endeavouring to feparate them. FAD is part
of the head.
Fig. 18, G H I K, reprefents alfo the piercers, and their cafe or
flieath, placed in the head, between the two fore feet ; which
piercers and their llieath are very difiicultly difcovered, unlefs the
fore feet be firft cut off clofe to the head, and even thus they will
feldom be fecn ; becaufe the Flea, when not viling its piercers, draws
them within the flieath, and places them clofe to its body. But as
a Flea, though its fore feet are cut off, will yet live a long time,
my way always was, when I endeavoured to get a view of the
piercers, to cut off its head, lefl:, when I had removed the piercers
from their pofition clofe to the body, and feparated them from each
other, the Flea fhould draw them again out of fight.
G I, and G K, are two parts, which, having cavities in them,
oppofite to each other, conftitute the fheath of the piercers ; which
piercers are placed in the cavity marked at G H. Thefe two flings
or piercers might indeed be taken for a tingle one ; but if we view
tlie figure narrowly, it will appear that the Jimner has pictured the
fecond fl:ing as it were within the fijlt, and not reaching quite to,
the end at H.
Fig. ig, LMNOP, exhibits the fheath of the flings or piercers
as I found them in a third Flea. Here I had better fuccefs than in
the diflection of the two former Fleas. For at L N and L O are
YoL. II. F
( 42 )
reprefented thofe two parts which, when joined together as I have
before laid, conftitute the fheath, and are covered with many hairs.
At L M and L P are the llings or piercers ; and in one of them,
L M, may be feen the cavity in which the other of them, L P, is
placed, when both are at reft : and when thefe two piercers are
inclofed in the Iheath, thefe four organs may be taken for one lingle
iiing.
While I was employed about thefe obfervations, my fervants
brought me a Flea, fixed to a fmall needle. Upon placing this before
the microfcopc, I faw not much motion in its feet, and the ftings
or piercei*s were put forth from their cafe; and the fting, L P, which
was inclofed in the cavity of the fting, L M, was moved up and
down in a very pretty manner, with great fwiftnefs, and as it were
in play.
Moreover, farther to gratify the curious, I pulled off one of the
Flea's hind legs ; in doing which, part of the mufcle belonging to
it was fcparatcd from the body, this I fixed to the point of a brals
pin, in order the better to place the whole leg before a microfcope
of greater magnifying power, and to caufe a drawing to be made
of its true fliape.
F/g. 20, B C D E F G H I K L M N, reprefents this hind leg; A B
is the mufcle, feparated from the animal's body at A. The firft joint
is flicwn at C D M N, and B C N is the part by which it had been
united to the body: in this firft joint might very plainly be fecn
four diftinA parts, lying longitudinally, and probably were tendons
and blood veftels ; which vellcls, and their more minute ramifica-
tions, I could plainly fee. This joint, and all the others feen.
through the microfcope, exhibited a tranfparent yellow colour, like
that of amber.
Between the letters D E L M maybe feen the perfect articulation,
whereby this firft was united to the fecond joint.
E F R L, reprefents the fecond joint, in the middle of which not
only the nervous or mufcular parts lying lengthways, were plainly
( -^3 )
to be feen, but alfo a blood veflel, diftinctly appenring to be coni-
pofed of annular parts, in which manner the blood veflels of
Fleas and other infects are formed, fimilar to the afpera arteria,
or the wind, pipe in the lungs of animals. And at one time, hav-
ing a Flea fixed by its hind part to the point of a needle, licfore
the microfcope, I faw throughout the whole length, on each fide
of this joint, as between E F and L K, and alfo, in the middle of
it, a wonderfully fwift motion or current of the juices, which ap-
peared to me the plainer as there were globules mixed with thofe
juices : but I did not notice this motion, except at the time the
Flea was moving its leg or foot, and then this motion continued
for fome time after the leg and foot were at reft. Many perfons
viewing this would fay, that they had feen the circulation of tlic
blood in the Flea's foot.
Moreover, upon the motion of the leg, as well in this joint as in
the others, there was fo great an agitation of the component
parts as is inconceivable. This agitation, I concluded, was only
caufed in the fleshy mufcles of the leg, becaufe it partly continued
after the death of the Flea ; but it was impoflible for the limner
to imitate, in his drawing, all the parts he faw: and he often, while
making the drawing of this leg and the other parts of the animal's
body, broke out into an exclamation, " Heavens! what wonders
here are in fo fmall a creature!"
F G I K is the third joint of the leg, in which may be feen many
fharp-pointcd particles, kicking out like thorns.
At G H I are Ihevvn the five laft or fmallert joints of the Flea's
leg, all formed in the fame manner ; and here plainly appears how
all thefe joints mutually depend upon, and are fubordinate to,
each other.
At II arc two perfectly formed claws : w ith thefe every one of
the feet is fumifiicd, and the Flea ufi^s them M'ith fuch wonderful
fwiftnefs and dexterity, that though when fiiut up in the glafs he
leaps about, and touches only a fmall particle of dirt or impurity,
F 2
( 44 )
though it were only a particle of his own excrement adhering to the
glals, he can, by a touch only of one claw, cling to it.
Now if we reflect on this wonderful and complicated formation
of joints in a Flea's leg, we Ihall ceafe \vondering that it can leap
to fo great a height as we fee ; nor alk the quellion (which I have
often had put to me) whether Fleas had wings to carry them fo far
and high?
Farther, I cut a maggot, produced from the Flea's egg, and was
almoll full grown, into two pieces, and placed each part before a
microfcope of the fame magnifying power as that by which the
maggot newly hatched was drawn : but if I had placed the maggot
entire before the microfcope it would have been impoffible, by
reafon of its continual motion, for the limner to have given a true
figure of it.
Fig. 21. A B C D, reprefents the head and three firft joints of
this maggot's body : I had placed it upright before the microfcope,
but before the limner had got it, the head was inclined downwards,
as fhewn at ABC; nevertheless this piece of a. maggot, for the
fpace of an hour, moved itfelf, and often lifted up the head.
Fig. 22. E F G reprefents the four latl joints of the maggot, con-
ftituting its hind part, in which not only may plainly be fcen, at
F, the organs or limbs with which the tail of this maggot is pro-
vided, but the place may alfo be dillinguifhcd where the excre-
ments are voided.
Now this maggot not being provided wnfh any limbs or organs
for moving from place to place, except what are feen in ^g. 21, at
D, in its head ; and in Jig. 22, as F. in its tail : the many hairs it
has on its body are a great help to its motion ; but, at the fame
time, are a very great hindrance to it, if it meets with any liquid,
mattei". So that even the hundredth part of the liquid excrement
voided by the Flea at one time, is fufficient not only to adhere to
thofe hairs on the maggot, fo as to Hop its progrefs, but ahb to
kill the maggot itfelf, by reafon that it is not able to extricate itfelf;
from the moillure : therefore, as we see how little able thefe mag-
{ <5 )
gots are to endure moiHure, we may conclude that, if in places
where Fleas abound, the floors or pavements be well wetted with
water, the maggots may be deflroyed, and confequently the places
cleared of Fleas.
I have caufed a drawing to be made of the glafs wherein I in-
clofed the Fleas I had under my obfervation, for the information
of any who may chufe to profecute my experiments. Fig. 23,
N O P Q, is this glafs, the cavity or orifice of which, N O Q, is
about the fourth part of an inch in diameter : the fphere or globular
part, O P Q, is fomething larger, according as may happen in the
blowing it. I did not put more than two or three Fleas at a time into
one of thefe glaffes, and as foon as they had Laid any eggs, I took
them out of the glafs, that it might not be foiled by their excre-
ments or the vapour of their bodies, otherwife the hairs on the
bodies of the maggots Vv^ould Hick to thofe foulnefles, fo that they
could not be taken out of the glafs, but would there expire.
I have now for feveral years obferved Fleas to lay eggs, and from
fuch of the eggs as were fruitful, maggots produced, which maggots
were afterwards changed into Fleas as before defcribed
Since we then fee fo plainly, that the Flea is endowed with
as great perfection in its kind, as any large animal; all v^^hofe limbs
may be feen with the naked eye, can any one give credit to the
idle tales of old ? one aflerting that Fleas are produced from fand ;
another, from dull ; and another from the dung of pigeons ; and
laflly, from urine : for that Fleas can be produced from dull and
filth, I utterly deny, as appearing to me impoffible : neverthelels,
that out of the dust of a floor or pavement. Fleas will fometimes
come forth, I readily grant ; but this is brought about in quite a dif-
ferent manner.
If many children be kept in a room, in which the Fleas are not
every day extirpated, and the floor or pavement is fometimes
fwept ; or if a floor or pavement be fwept near to a place where a
dog is accullomed to lye, there may very eafily be taken up among
( ^& )
the fweepings, not only young maggots from the eggs of Fleas, hut
full grown ones, and out of the chinks or cracks maggots may he
fwcpt, fome of which are fpinning their wehs, and others, which
have completed them, and are changed into cryfales ; fo that out of
fuch fvseepings Fleas may come forth day after day : and it may
liappen, that maggots newly hatched, may among fuch dult and
rubbilh find fomething to afford them nouriihment, fo as to grow
up to be complete Fleas. And I am the more inclined to believe
that this may be the cafe, becaufe I could never get out of any dog,
how much foever he was infefted with Fleas, any of their eggs,
nor fee any about his body. But if we take a cufhion covered with
a green or any other dark colour, and let a dog lie on it who is in-
fested with Fleas (which I have often done), we ftiall find that the
Fleas do not lay their eggs upon or near the dog, but the eggs will
be found in the corners and fewings of the cufhion, where, by their
whitenefs, they will eafily be difcerncd.
AN'e have, indeed, moderns vho favour those old opinions, of
whom I will only fay, that if they were prqvided with a good mi-
crofcope, and would attentively beftow a few days, as I have done
many, in the inveftigation of the fubjeft, they would not broach
fuch fables and childilh tales, as they now write and publifh to the
world.
4V
l^i^ -«^ vvg
i^(LIBRARY)-
On the feeds of Trees, tvith the author s reafoning and obfervafions
on the poffibility of intermixi?ig two different fpecies of tree, fo
as to produce a third, partaking of the nature of both. A fin'
gular peculiarity in the feed of Cotton.
VJ PON an accurate examination of every kind of feed, we fhall
difcover in it the origin or firll formation of the leaves and root of
the future tree or plant, according to the refpedive fpecies of fuch
feed.
This is particularly obfervable in the feed of the Afh, which is
reprefented of its natural fize in plate XIII. fg. 1. In this feed,
though no bigger than here pictured, I difcovered not only two
leaves, but also that part froni which the root would grow, being
all very large in proportion to the lize of the feed.
Again, all feeds in their formation, on the parent plant, receive
their nourifhment from a fmall ilalk, ftring, or ligament, conlifting
of many veilels through which the nutritive fubllancc is conveyed,
analogous to that which in animals is called the navel firing. In
fome feeds this flalk or ligament is very fliort, in others as long, or
longer than the feed itfelf. I will give fome inllances of this, be-
ginning with the feed of the Afli..
Fig. 2. A B is the half of the fhellj cafe, or covering, inclofing a
feed of the Alh.. A D fliews where the fmall feed E F was placed,
and from wlience being taken out, as reprefented in the figure,
there appears the firing or ligament A F, through which the whole
feed E F received its nourifliment, being derived from die part A,
which was joined to the tree, and through which alone the fame
can be conveyed. It is also to be obferved, that the part in the
feed whence the future root will proceed, is at the point F, where
the ligament is joined to it ; fo that the leaves of the future tree
when in the feed, while it is united to the parent tree, are placed,.
( 48 )
as I may fay, with their points downwards, and their roots and
ilalks Ujnvards. But we mull confidcr that the feeds of the AHi,
which grow in * chillers on the tree, do at length, by their weight,
hang downwards, and that the fame is the cafe witli apples and
pears, which while they are very fmall. Hand erecl on their ftalks,
UTid confequently the origin of the future plants formed in them, is
placed with its root upwards ; but when the fruit grows to fuch a
lize, as by its gravity to hang downwards, then the young plant in
the feed or kernel, has its root and leaves in the fame pofition as it
will have when growing.
Upon opening the feed of the Alh, I found in the middle of it
two large leaves, and a) lb the firft rudiment, or beginning of that
part which woidd become a root, and thefe leaves were larger than I
have obferved in the feed of any plant whatever. Thefe leaves when
examined by the microfcope, appeared as \n fig. 3. C D E F, and I
found them to conlitl of an immenfe number of thin roinid promi-
nent globules, which I endeavoured to imitate in the drawing, though
they are not there reprefented nearly fo fmall as they appeared to
me. I alfo faw in thofe leaves a great number of fibres, or more
properly veflels covered with wonderfully minute globules ; which
veflels, but without the globules, are reprefented in the figure : thefe
velTels arife from the infide of that part whence the future Item or
trunk of the tree, and alfo the root are produced ; which is pointed
out in the figure at A B C F G H. This lall mentioned part which
would produce the Hem and root, befides thofe veflels from which
the fibres of the leaves ilTue, and which may properly be confidered
as the marrow or fap of the wood, is moreover provided with many
veflels ; and in order to reprefent thofe veflels in a clearer light, I
cut a piece tranfverfely, at the place marked with the letters B G,
and having placed the piece or flice before the microfcope, I made
as exact a drawing as I was able of it, with all the veflels in it, as
* In England, thefe cluftors of feeds on the Afli, from the rcfemblance (hey bear to a
Auuch of keys, arc called Afli-kcys.
(-19)
they appeared to me, a rcprelentation of which is given at fig. 4.
I K L M. In this fmall particle, I not only judged that there Nvere
about a thouland vcllels taking their courfe upwards, but. it alio
gave me a rcprelentation of a complete branch of tiie tree cut tranf-
verfely ; for the external furface reprefented the bark; the part next
it, in which are very fmall dark fpots, denoted the wood; which dark
colour was only caufed by this, that in cutting the flice, the knife
had Iqueezed together, or Itopped, the fmall tubes or veflels of which
it was compofed ; the middle part, the fap, or thofe veflels which
would produce the Item or branch, and being cut tranfverfely, ap-
peared round bodies. But this figure was drawn from a microfcope
of greater magnifying power than that ufed in the former, in order
to fhew the nature of this flem and root more ditlinftly, fb that the
diameter of this figure at I L, is about twice the diameter of the part
marked in the lall figure by B G.
]Sroreover, in this fmall trunk or flem, I perceived in fo me places,
fome round particles, as if they were fmall round corpufcles in the
tubes or velfels, which are reprefented between the letters A
and B.
I have thought it right here to exhibit the fize of the young
leaves in the feeds of fome other trees, to fhew that it by no means
follows of confequence, that the largell feeds contain the largeft
rudiments, or originals, of their future plants, for the young plants
in the fmall feeds of the Afli are vatlly luperior in fize to the very
fmall leaves which the large feed of the Walnut contains, and
which, as feen by the microfcope, are fhewn at jig. 5 and 0, the
origmals of which I took from two feeds of that fpecies, in order
to note if there might be any material difference between any two
of them. In thefe figures I have only reprefented the leaves, be-
caufe in the rudiments or originals of the future flems and roots,
(which in this feed are fomevvhat longer than the leaves), I per-
ceived little or no difi'erence in the form from thole in other feeds.
In drawing thefe two figures, I found it quite impofTible to repre-
VoL. II. G
( 50 )
fent the very minute globules of which thefe young and unformed
leaves were compofed.
I have in another place faid, that there are no blood veflels
intermixed among the fmall fibres or flelhy ligaments of which a
flelhy fibre conlills ; but that the blood veirds which furround the
flelhy fibres, are placed in or between membranes ; and 1 have alio
laid down my idea^ how tar the flelhy fibres are nouriflied from the
blood veflels ; lb in this cafe, I fay, that all the leaves of trees and
plants are formed of globules (befidcs the veflels or fibres of the
leaves), all inclofed in a membrane conllituting the furface of the
leaf, and the manner in which, I imagine, that thefe globules, al-
though they touch no vcfTels, are yet nouriflied by the veflels, I
take to be this : we mull first underlland, that almoll all the leaves
of trees and plants, \\ hile united to the plant, confifl of two third
parts water or a watery fubftance, and that the globule?, of which
for the greatell part, the leaves confifl, do not lie fingly or feparate,
but many of them heaped together. Thus let us fuppofe jig. 7,
A B C D E, to be the veflels in a fmall piece of a leaf, and that thefe
veflels have a great quantity of globules, which in the nourifliment
of the leaf are fupplied and fupported by the veflels : then upon
the globule F receiving a fupply of nourifhment, particularly water,
from the veflels to which it is clofely conjoined, it mufl neceflarily
impart this nourifhment to G, and that the fame nutritive fubflance
will be conveyed from G to H, not only becaufe thefe globules are
clofely conjoined together, but alfb becaufe as before mentioned,
the greatefl part of the fubflance of the leaf, and confequently of
each globule, confifls of a watery matter or fubftance ; and thus,
thofe globules which are next the veflels, cannot receive any nou-
rifhment from them, but they muft impart of it to thofe globules
next to them, and thofe again to others. I have formerly com-
pared this communication of nourifhment to dry globules or balls
of clay, which we will fuppofe lying in a glafs, and only one of
tliofe balls to be made wet, and the moiftening being continued,
( 51 )
the other balls of clay contiguous to this moill one, receive the
moiflure from it and become wet, and thefe again lying in contact
n\dth others, at length all the globules or balls of clay will, by
means of the firft globule, become wet; and this is the cafe in the
nourifliment of leaves and alfo of fruits.
Fig. 8, ABC reprefents the outfide of the young leaves in an
Almond, and upon removing them, I perceive feveral leaves in-
clofed in them. Fig Q, AB C, is the outllde of the leaves in the
kernel of a Cherry, an I ^o-. iq, ABC, the leaves, as they appeared
to me, in the kernel of an Apple.
Now, if in fuch fmall feeds as thofe which produce the Afli (one
of the largeft trees growing in this country), and which feed is fo
light, that fix of them fcarcely weigh four grains, if in thefe feeds,
I fay, we difcover, not only the perfeA leaves with their vellels,
but alfo the ilem and root of the future tree, and thefe much plainer
and larger than in the Walnut or Hazle, we fhall alfo eafily per-
ceive that wife and provident Nature in all her operations, and
efpecially in the propagation of plants and animals, perfects her
\vork, by ways and means limilar or analogous. * For the feeds
of trees and plants not only contain in them the origin of the future
plant, but alfo a white fubftance which we denominate meal, in
order to nourifli and fupport the young plant, until it has ftruck its
roots into the earth and can draw nourifliment from thence. Be-
lldes which, many feeds are provided with an oily fubflance,
whereby the young leaves and plants are kept from drying up, and
■\- many feeds which have not this oil will not remain long good out
of the ground.
* In the original it is " all feeds mufl neccflarily be provided with a mealy fubftance,"
ice. but this is a miilake which the author corrects prefcntly afterwards in his account of the
feed of Cotton.
+ This is particiilaily (he cafe with the Acorn, which by nature is defigned to Tegetate
immediately after it quits the tree.
G 2
( 52 )
Fig. 11. G H I is the half of the hard fliell of the Filbert. K L M
is the nut or kernel taken out of the fliell. G is that part of the
fliell which was united to the tree, in which part there is a very looie
or fpongy pallage through which the ligament of the nut or kernel
palfes, as G L, to convey the nutriment for the formation of the
young plant, and alfo a futlicicnt quantity of aliment to fupport it,
when the nut is fown or planted, until the root of that young plarrt
in the nut, has extended itfelf fo far out of the hard fhell as to reach
the earth. This figure alfo fliew^s that the fubftance, which through
the ligameht is conveyed for the fupport of the nut, does not at aU.
arife from the hard fhell, but that the ligament having a paflage
through the Ihell, conveys the nourifhmcnt from the tree itfelf.
Thefc firings or ligaments, w^iereby the young plant and the rest
of the fubftance of feeds is nouriflied, have alfo coats or barks of
their own, and within this coat or bark in the ligament of a Filbert,
I think there are abo\^ an hundred fmall veflels, all which, as far
as I could fee, are formed of fibres in a twifled fhape, in like man-
ner as if one were to wind a piece of fmall copper wire round a pii:^
and then draw out the pin from the wire, leaving it in the, form de-
lineated at^^. 1 2, A and B.
It is worthy of confideration refpe(3:ing thefe ligaments, that in
almoll: all feeds the ligament is joined to that part of the nut or kernel',
from which the young plant will fhoot, as may be feen at fig. 1 3,
letter A, (which is a Filbert drawn fomewhat larger than the na-
tural fize, in order to fhew more eafily the courfe of the velfels pro-
ceeding from the ligament), in which figure the ligament takes its
courfe from A to B, and in its paflage fpreads itfelf into divers
branches, and thefe again into fmaller ones ; and thus fpread through
the whole nut, which hgament, or the veflels arifing from it tend
to the fame point, and finilh where they begim, that is, where the
young plant will be produced.
I made a tranfverfe fedion of the ligament by which the Almond
is nouriftied, becaufe it is fomewhat thicker than that in the Filbert^
I 53 )
and made a drawing of it as feen through the microfcope, which is
to be seen at Jig. 14, CDEFG. This ligament is divided into
feven compartments, whidi compartments are of a reddifh colour ;
the velfels they contain, I have reprefented in the figure as they are
placed in one of the compartments at F G H ; and from a view of
the veflels in this tingle compartment, any one may eafily figure to
himfelf the great number of veflels in the ligament, by which the
Almond, the Filbert, and moft feeds are nourifhed ; for upon exa-
mining the ligament of the Filbert, I found no difference in it, ex-
cej^it that the ligament of the Almond was larger in every part.
In my remarks and contemplations refpe(3;ing the propagation of
trees and the nature of feeds, I turned my attention to the Willow,
which is no otherwife propagated among us, than by cutting off a
branch and planting it in the ground, where it grows to a tree. But
becaufe I had obferved feveral Willows growing in fields and on the
banks of flreams, in places where I judged they were not planted
by hand in the way I have defcribed, but to have been produced
fi'om feeds ; I turned my mind to difcover what was the fruit or pro-
duce of the Willow, in order to difcover the nature of its feed. The
only fruit of the Willow is a kind of wool or cotton produced on it,
about the beginning of the month of June, and at that feafon, tipon
examining this cotton, I faw lyi"g i^ ^' many dark coloured parti-
cles, a little larger than grains of fand. Upon viewing thefe parti-
cles by the microfcope, I found them to be the feed of tlie tree, and
that the cotton and thefe feeds were formed in a kind of cells of a
violet colour, and of thefe cells I counted feventy-five, placed near
each other on a fmall branch, which feemed deflined for no other
purpofe but to produce the feed> and in each of thefe cells, three,
four, or five fmall feeds lying among the cotton ; and I could per-
ceive that the cotton was formed out of the feeds in the time of their
growth. Thefe feeds were of the fize reprefented at fg. 1 5 : the
cotton of the feed was in two, three, four, five, and fometimes of
fix filaments, joined together by a kind of knot and united to the
( 51 )
feed : and when the feed and cotton were fully ripe, the cells in
which they were contained, burll open, and the cotton loofed itfelf
from the feed, and then each particle of cotton which before had
laid in regular order belide each other, as at Jig. lO, ftarted
afunder, as rcprefented at j^^. 17; by which means a fmall
quantity of the filaments of the cotton being fo widely difperfed,
■was, with the leaft wind carried away, bearing with it many of
thofe minute feeds, and flying over walls and buildings, could de-
pofit tlie feeds of the Willow in very diftant grounds. Upon nar-
jowly infpecling this feed, I faw that the part from whence the fu-
ture root would arife, and which was about one third of the feed,
was provided with many veflels which feemed to conlill, for the
jnoll part, of oblong and round particles. The reft of the feed
confifted of two parts joined clofe together like leaves, very folid in
proportion to their lize, of a dark green colour, and feeming to be
formed of globules. Having fcparated thefe afunder, I faw two
very minute protuberances, which I imagined were the beginnings
of two leaves, and the origin of the future tree ; hence I concluded,
that the firft two parts \^ hich 1 have compared to leaves, were only
defigned to afford nourilhment to the young plant, until it fhould be
provided with roots, by which it could extrad: its nourifliment from
the earth.
In order further to fatisfy my curiofity refpccting this very mi-
nute feed, from which fo large a tree as the Willow is produced,
I took fome of the feeds, and, in the month of June, placed them
in moill fand in my clofet, in order to fee how the beginning of
vegetation would be performed in this very fmall feed. But before
I put the feed into the fand, and while it was yet very dry, I viewed
it with the fame microfcope from which the drawings of the pre-
ceding young formed plants are taken, and it appeared as rcpre-
fented 'dt Jig. 18, ABCDEF: but thefe feeds were of very dif-
ferent fhapes, for in drying they became crooked, fbme more than
others. ABE F, is that part of the feed from \\ hence the root
would arife.
( 55 )
When this feed had lain in the wet land thirty-fix hours, it ap-
peared as at jig. 19, G H I K L. And here it appears how much
of the feed was to form the root, which is marked by the letters
GH K L ; and it was not only grown longer, but in the very fliort
fpace I have mentioned, fix diltindl; roots had grown out, as repre-
lented at G L ; and thofe parts, H I K, which I have defcribed to
be like leaves, and which, while the feed was dry, could not be
feparated without the greateft difficulty, now opened as it were of
themfelves, to make room for the plant contained between them.
And when this feed had remained in the moill; fand feventy-two
hours, I found that the roots had fpread themfelves into divers
branches, which were fo fi:rongly twifiied among the particles of
fand, that it was impoflible to feparate them without breaking the
roots.
It is well worthy of remark, refpecting the Willow, that the feeds
are ripe befare the leaves on the tree are grown to their proper
fize, whereas the fruits of moft trees, and confequently the feeds
contained in them, do not arrive at maturity till much later in the
fummer, or elfe in autumn ; fo that in the Willow, the feed being-
ripe in the fpring, a new tree may be produced from it the fame
year. This I have alfo obferved in the Elm : for, about the end of
May, I took fome feeds, which are of a very fmall fize, from an
Elm, when the leaves on the tree were about half grown : thefe
feeds, which were dry, I put into wet fand, and after three days
they began to grow. 1 have alfo found that the Poplar tree, which
produces a cotton formed with two flat fides, like the Willow cot-
ton and the Indian cotton, produces its feed about the end of May,
or the beginning of June.
Here we fee, that in fuch a fmall feed as that of the WilloWj
not only the young plant and the root of it, which is provided with
veflels as if it was a complete tree, can be feen, but alfo that
within fix-and-thirty hours tlie feed will begin to grow, even in
a clofe room, fo that the young roots may be dillinctly feen,
( 50 )
I have fometimes thought, that if it was poffible to take out the
young plant from any feed, and unite it to another feed, in that
place where the young plant was formed in that feed, a tree or fruit
would from thence be produced of a fpecies unknown before : as,
for example, if we could take out the young plant from the Walnut,
and unite it to the fubllance of a Chefnut, a tree would be pro-
dirced not like either of the trees from whence thofe fruits were
refpeetively produced, and confequently a tree of a new fpecies.
And a certain eminent gentleman hearing me mention this, urged
me rtrongly to make the experiment, faying, that though of thofe
two feeds only one could vegetate, yet we might expedl that fome
tliird plant of a new fpecies would be the refult. For my part, I
confidered the thing as impoflible to be performed, and fo I found
it upon further invelligation of the fubjeifl ; but as there are not
many men well informed in the iirft formation or growth of trees
and plants, I will here defcribe the nature of the firll formation of
the young plant, both in a Chefnut and a Walnut.
Fig. 20 is a Chefnut, broken in half; A is the rudiment or firfl
"beginning of the plant, and though the Chefnut is a verv large
feed, yet the original or lirll formed leaves can very rarely be dif-
covered in it ; and indeed I mull confefs, that among many Chef-
nuts I found but one in which I could difcover the two leaves of the
young plant ; the upper part of the young plant was fomewhat of
a round form, and furnished with a fort of cavity. This beginning
of the plant, marked at A, is not only firmly imited to the fub-
fiance of the nut, but there is one remarkable particular in it,
different from other plants, that it has not only two ftrings or
ligaments to convey nouriihment from the Chefnut to the young
plant, until it is of fize and ftrength to draw nourifhment from the
earth, but thefe ligaments are provided with a great number of
veflels, having their rife in the Chefnut, to convey the nutritious
jaices ; and thefe veflels produce others in the root and Hem. Thefe
( 57 )
veflcls are of the fame formation as I liave already defcribed tbe
ligaments of the Ahnond and Filbert.
Fig. 21, A B C is a Chefnut, which I put into an eailhen veffel
filled with moift fand, and placed in the chimney, it being in the
winter feafon, and watered it every fecond, third, or fourth day, ac-
cording as the difference of heat feemed to require : C D and A E*
are the two ligaments to which the young plant is united ; F G, is
that part which will fpring up to a ftem ; G, indicates the leaves be-
ginning to flioot ; and E HD, the root. And here we fee to what
ufe the Chefnut is delHned, namely, to fupport and nourifli that
fmall part contained in it, which is to conltitute the future plant ;
and this is performed througli the two ligaments, until the young
plant and its root are grown to a fufficient fize to draw their nou-
rilhment from the earth.
Fig. 22, is a Walnut, fo divided or cut as to fhew, at I K, the
origin or firft beginning of the young plant. And whereas I have
faid, that in a Chefnut the young leaves are not to be diftinguhhed;
on the contrary, they may eafiiy be feen in a Walnut : for in every
one of them that I examined, I could, with the microfcope, as
plainly fee the leaves, as with the naked eye we can fee young
Jeaves in the fpring. 1, denotes that part whicli will grow into
branches and a tree ; K, the fliarp-pointed part fi'om which the root
will ilTue,
I alio treated feveral Walnuts in the fame manner as I have men-
tioned refpeding Chefnuts, in order to obferve their vegetation.
Fig. 23, LMNOP, is the Walnut ; Land P, are the ligaments,
to convey nourifhmcnt from the root to the young plant. Thefe
are provided with a great number of veflcls, which, from the oh-
fervations I made on two feveral feeds, I was well allured were
fpread through the whole fub (lance of the nut, or feed, in ord(;r to
convey its moft nutritious juices to the young plant, until it Ihould
be fiifficiently grown to draw its nourifliment from the earth ; R P,
is the root.
Vol. II. H
( 53 )
From thefe obfervations, lliewing the dole connedlion of the
young plant by the ligaments with their multitude of veflels, with
that mealy fubllance which we call the feed, it plainly appears, that
we cannot take out the young plant from fuch feeds, without
])reaking thofe ligaments and their veflels ; and when they arc
broken the young plant is dead, and cannot be removed into any
oilier feed ; fo that it feems to me impoffible to remove the young
plant from a Chcfnut to a Walnut, and fo to place it that the Chef-
nut ihall grow in the Walnut.
And tliough wc may be able to take out the young plant from
the feeds of Afh, J.ime-tree, Goofeberries, Currants, or the like,
without breaking the ligaments, or rather without obferving them,
vet we mud conlidcr that were there are no lijraments with veflels
in them, yet, in fl:ead of them, the globules compofing the mealy
fubflancc of the feed are placed in fuch order, and fo clofely united
to the beginning young plant, that they either fupply the place of
A'eflels, or in reality are veflels, the true fl^rudlure of which is to
us infcrutable. Moreover, there will be always a confldcrable dif-
ference between the fize of the young plants in dilferent feeds, and
confequently the place whence the plant is taken in one feed, will
be too fmail or too large to receive the young plant from another.
Add to which, that we cannot take out the plant without break-
ing the feed, which, by fuch breaking, will become ufelefs. So
that it is plain there is no pofllbility of taking the young plant out
of one feed, and uniting it with the farina or mealy fubflancc in
another.
I have faid, that feeds contain in them not only the firft rudi-
ments or origin of the future plant, but alfo a mealy tubflance,
and fome of them an oil ; which mealy fubftance is defigned by
Nature to noiirifli and fupport the young plant, until its roots are
fo far grown out of the fliell that they can draw nourifliment from
the earth. But, upon examining the feeds of the Cotton tree which
( 5Q )
grows in Perfia and Bengal,* and which feeds are found among
the cotton brought to us from thence ; I was aftonillied to fee the
variety of Nature's operation in the formation of this feed. For,
upon opening thele feeds, of v/hich ftven, eight, or nine are con-
tained in one fhcU or hufk with the cotton, I did not fmd any thing;
of a mealy nature or fubllancc, but the oblong round figure of
the feed is only caufed by four diilinA leaves, with wonderful ex-
a6lnefs doubly folded together, and as it were embracing and de-
fending that part from which the Hem or root will proceed. I
caufed a drawing of this to be made, fomewhat magnified, in
order to Ihew the leaves, with their fibres or vefiels, and alfo cer-
tain dark round globules which are to be {gcti on the leaves : thefe
are (hewn Sit_fig. 24, DEFG. When I cut thcfe globules open
as exactly as I was able, the pieces cut off exhibited the brightell
grals-green colour that can be imagined ; a particle cut thicker
was of a darker green ; and the globule viewed entire was of a
deep green, verging to a black colour, a b c. Are three pins, with
which the leaves are fpread open. The fubftance of thefe leaves
was compofed of exceeding fmall globules, of a kind of grafs-green
colour. I enquired of feveral perfons who had been in India,
what was the form and nature of the leaves of the Cotton tree,
but among all to whom I addrelfed myfelf, I only found one gen-
tleman and lady, who told me that the leaves of thofe trees were
marked with fpots. Here we fee the wonderful regularity of Na-
ture's works, namely, that in the feed of this tree there is not only
formed a perfect }oung plant, but the leaves in that young plant are
dotted with points or fpots, in the fame manner as the leaves
growing on the tree. In the figure, D E is that part from which
the Hem and root will be produced, and, upon cutting it open, I
found in it a very few grafs-green globules.
• The Cotton tree is now caltiyated in the Weft Indies, where it forms a confidcralle
branch of trade.
» H 2
( 60 )
Thcll* obfervatioiis recalled to my mind (for I compare thofe
feeds with thofe eggs which I have heretofore taken out of the bo-
dies of fomc infects) that in fome of the eggs fo extracted, I did
not find any fnbftance dellined to the nourilhment of an animal,
but, iullead of it, perfcd and hving animals. For in like manner
as in thofe eggs, while yet in the parent's body, a perfedl young
one is formed, lo the Cotton tree produces in its feeds not only the
leaves of the young ])lant, even while the feeds are yet on the
tree, but that part in (he feed irom whence the root and Hem are
to be produced, is in this leed uncommonly large.
And in like manner as with regard to the eggs of the infedls,
I have mentioned, that as foon as the young one has broken the
egg, it immediately comes forth and runs, creeps, or fwims about ;
fo the leaves in this feed having received the moifture requifite for
their growth, do fwell and enlarge themfelves until the thin fkin
wherein they are inclofed burfts or cracks, and the leaves then
expanding, that part whence the root and llcm will proceed grow
to a futficient length to draw its nourifliment from the earth. In a
word, fome infe6ls are perfetl in their eggs before they are voided
by the parent, and the plant in the fe^d of the Cotton tree is per-
fect, and requires no nourifliment to be provided for it when it is
of fuflicient maturity to quit the tree.
I cut a flice tranfvcrfely from that part whence the root and
ftem derive their origin, and caufed a drawing of it to be made
from the microfcope, for no other reafon than bccaulc the internal
part containing the veflels, which iji others is of a round or oval
figure, is in this a figure of eight fides, four of which are fome-
what curved, as at fig. 25, A BCD, which was full of pores: the
part furrounding it, which appears at E F G H, was very white,
and in it I could not difcern any pores. The outward part or
compartment, I KLM, both in pores and in its white colour was
fimilar to the internal one, with this difference only, that the pores
in the inner one were fomewhat larger. And though the greateft
(61) -
part of the feeds which I examined were very old, yet I found that
this young plant contained in it a confiderable quantity of oil.
Some other feeds I opened, in which the young plant was fo frcfti
that I thought I could make it vegetate, but I have yet met with
no Cotton feeds which I could by any means caufe to grow.
I afterwards faw, in a curious gentleman's cabinet in this town,
fpecimens of two other Indian feeds, in which the leaves and root
of the future young plant were extraordinary large, but no oil or
mealy fubftance, fo that we find there are fome feeds which contain
only the young future plant or tree.
If any one is defirous of feeing the young plant in great per-
fedion, as it hes in the mealy fubftance of the feed, let him ex-
amine the feed of the Lime tree * when ripe ; for in this feed are
to be feen two leaves not flattened nor folded up, but of a perfe6l
handfome fliape, the fame as a young leaf on the tree ; and through
the microfcope the veiTels or fibres in the leaves are as plainly to
be feen, as with the naked eye we can fee them in a full grown
leaf: the origin or firfh rudiment of the young plant, which in
this feed is extraordinary large, is placed in the contrary direction
from the parent tree, whereas in other feeds it points towards the
tree : this young plant, before it comes to its full growth in the
feed, is not of a green colour, but when full grown it becomes of
a bright yellowifh green.
* A figure of this is given in Baker's Employment for the Microfcope.
■i-
On the generation of EELS.
It is the common opinion in this country, that Eels are produced
Avithout the ordinary procefs of generation ; a notion which I could
never conceive, as 1 have often dechired ; and 1 will lay, that it
this were true, there is no reafon why Eels fhould not be produced
in fuch quantities, as in a manner to fill all our canals.
Nevertheless, this opinion is not only entertained among the
vulgar, but I have found fome rcfpe<ftable and learned men inclined
to favour it ; and they have gone fo far with me, as to afl'ert, tliat
they knew in \Ahat manner Eels were generated, which they ima-
gine to be as follows :
If in the month of May, two turfs of grafs be taken and laid on
each other with the gralfy fides together, and before fun-fet be
placed in the water, fo that the grafs of thofe turfs be even with
the furface of the water, and if the dew fall copioufly that evening,
upon taking up the turfs, the following morning, feveral minute
Eels will be found in the grafs, which they fuppofe proceed from
the dew ; in confiimation of which they add, that if no dew has
fallen, there will be no Eels found.
But upon examining this matter, we muft confider, that in very
windy weather no dew falls, and fmall Eels in cloudy M^eather, get
to the bottom of the water ; but the warmer and calmer the wea-
ther, the more is the dew that falls : moreover, thefe minute Eels
in warm \^-cather, fwim or creep among the leaves and greens on the
iurface of the water, and do moll probably, at the lame time, creep
among the blades of grafs near the furface ; and this, I fuppofe, has
given rife to the notion of their being generated in this manner.
In farther refleding on this fubjedl, it occurred to me, that I
had often in fummer time, fcen boys by the fides of the ditches
round about this tov\'n, with fmall twigs, which they dipped among
( 03 )
the leaves fwimming on the furface of the water, and, twifting the
twigs round, fo as to lay hold of thofe leaves and draw them out of
the water, they pulled out with them many minute Ee s ; and
among thofe, I have feen many young Eels of different fizes, fome
of them remarkably minute and fmaller than we ever obferve the
young fry of fiflies which are produced from eggs ; and this con-
firmed me in my opinion, that Eels are not always bred in the fame
month or feafon of the year.
In order farther to inveftigate this fubjed:, I, at feveral times,
difleded fome large Eels, examining particularly that part of the
belly where one experts to find lome appearance of young, (and I
am well afllired, that Eels of every kind, without diftindlion, do
breed young ones), in the inteltines of which I found many dif-
ferent kinds of animalcules ; and afterwards I examined fome Eels
without dilfeding them, by comprefilng the belly near the
aperture into the inteftines : from one of thefe there iflued a fmall
quantity of thick liquor, which being diluted and placed before the
microfcope, I plainly faw that it contained animalcules, which in
fhape, length, and thicknefs, exactly reprefented Eels, but fo mi-
nute, that in my opinion, they were not a fiftieth part the thick-
nefs of a hair.
After this, upon reflecting that Eels might probably breed in the
winter time, I directed a filherman to bring me fome every week,
beginning in the month of February.
The firrt of thefe I diflected, and upon examining the parts where
I fuppofed the young would be depofited, I found nothing but fome
very minute globules, fomewhat lefs than the globules of blood,
and of thefe fome were of an oblong fhape : proceeding in my
obfervations, I found thefe kind of globules more and more ex-
tended in length, till I faw them of the perfedl Ihape of Eels, and
at laft I extracted a great number of minute Eels, lying together in
a tranfparent liquid, which, through the microfcope, appeared as
perfedly formed as minute Eels viewed with the naked eje.
( O-i )
This Ipeclacle gave me great plealure, parti) becauie, after taking
fo mucli pains, I had now diicovered the manner of the propaga-
tion of Eels; and partly, hecaufe this was a complete anfwer to
thofe who faid hehind my back, " Since ISIr, Lecuwenhoek is en-
** deavonring to eftablilh the regular generation of all animals, let
" him Ihew us in wliat manner Eels are bred."
The fight of thefe minute and perfedl, though unborn Eels,
which were, as I have before faid, not a fiftieth part the fize of an
hair, I exhibited to feveral of my acquaintance, who wondered to
fee inch minute creat\ires fo completely formed.
I purfued my oblervations on this f\ibje6l: till the months of Au-
guft and Oclober, till I could barely fee thefe minute Eels with the
naked eye, and I judged that they might at that time be brouglit
forth into life b}' the parent.
It is by ibme alferted, that from the Ikins of Eels thrown mto
the water Imall Eels will be produced. This may perhaps be tme,
though not, as they imagine, from the corruption or putrefciction of
thofe Ikins, but in the following manner. Let us fuppofc that
among a fcore or more Eels which have been Ikinned, one of them
may have fome minute young ones in its belly, which, by the pref-
fure in the operation of ikinning, might be fqueezed out and remain
adhering to the Ikin ; thole minute Eels, when thrown into the
water M'itli the Ikin, may there find food and grow to their full fize;
and by this means, if Eel-Jkins are thrown into a newly made
^'anal, Eels may thereby be bred therein.
On the multitude of eyes or optical organs in the eye of a Beetle.
The optic nerves of each of the optical organs in the eye of a
large Fly, particularly dejcribed : aljo the brain of a Gnat ; and
the nature and probable ufe of the hairs on the feet of Flies
and Crab-ffh.
X HAVE formerly made mention of the great number of optical
organs, or eyes, with which fmall flying animals, such as the
dragon-fly,* or libella, the common fly, and others, are furniflied ;
and I have often fliewn thofe eyes to fome curious gentlemen,
when they came to vifit me, to their great delight, particularly
when they found that obje<5ls ipight, with the greatefl: clearnefs, be
difcerned through each of thofe optical organs, to the number
of feveral hundreds at a time.
Among other inftances, I, upon a certain occafion, exhibited
to feveral Englifli gentlemen of rank, the great number of optical
organs which are found on the tunica cornea, or horny part of
a Beetle's eye; at which fight thofe gentlemen were aftoniflied,
and the rather, as it is a kind of proverbial expreflion in England,
when they would reproach any perfon with blindnefs or fl;upidity,
to fay, " He is as blind as a Beetle," under a notion that that animal
is void of fight.
With regard to this creature, I began " by feparating from
the head that part which is commonly called its eye, and, having
cleared away the blood veflels, and other matter adhering to it,
I placed it before the microfcope, and then I faw that the protuber-
ance, or rifing of this eye, was not a perfed hemifphere, being
rather more extended in length than in breadth.
* This creature is vulgarly called, particularly by children, an horfe-flinger ; but Tery
erroneoufly, for it has not a fting, nor any weapon of offence, that is discoterable by us.
I
( 06 )
I alio made a computation, as accurately as I was able, of the
number of optical organs which were to be feen, in a row, in
the largell fcgment, or longell fide of the eye, and I found the
number amount to fixty ; and if we fuppofe that, in the fmalleft
fegment, or narrowed part of a Beetle's eye, there are forty fucli
optical organs in a row, thefe fixty and forty, added together, make
one hundred ; the half of which, being fifty, is what we mull take to
be the number of eyes in the hemifphere which compolcs a Beetle's
eye, if we confider fuch eye to be of a fpherical fliape.
Now, if we fuppofe that the two eyes of a Beetle do, together,
make up a perfect fphere, and that in a great circle* on fuch fphere,
one hundred optical organs are placed, we fliall find, according
to this rule laid down by Metius, " As 22 is to 7, fo is the
" quadrature of the great cii"cle to the contents of the fuperficies,"
and the rule being applied as follow^ :
i* • la^ j > a
7
10000
7
1 00 the great circle
100
22) 70000 (3181
10000 Quadrature.
•40
180
•40
18
the refult is, that if each eye in a Beetle's head is taken as an hemi-
fphere, the two Mill make up a fphere containing, on its furface,
3181 optical organs or eyes.
I have caufed a drawing to be made of the eye, or rather of the
* It has been mentioned in another place, but is here repeated to favc the trouble of
turning back, that by the great circle is meant, the largcft which can be drawn upon a globe,
or fphere, or, in other words, a circle, M-hofc diameter is a line paffing through the centre of
fuch fphere to the furface.
( 67 )
multitude of optical organs compofing the eye of the Beetle, as far
as the limner was able to difcover their ftrufture by the help of the
niicrofcope, with intent, partly to exhibit the great number of thofe
optical organs, and partly to lliew that each of thefe organs is
of a convex Ihape ; not that I would be underllood to mean,
that every one of thefe optical organs is a portion of a fphere;* for,
if lb, the Beetle would not be able to difcern obje6ls at any dillance,
but that each of them is more flattened than fpherical.
Upon exhibiting this objedl; to the limner, he compared thefe
convexities, or protuberances, to thofe round buttons which are
at prefent ufed in men's clothes, and made of that metal commonly
called Prince's metal.
Plate XIV. fg. 1 , A B C D E F, reprefents a part of the tunica
cornea, or horny part of the Beetle's eye. ABC denote that part
which was contiguous to the head. D E F A reprefent the greateft
part of the longell row of eyes on the fuperficies of the tunica cornea ;
in which, from D E F to A, I counted more than lixty optical
organs ; and, between the fame letters, may be feen how each of
thefe optical organs rifes with a kind of protuberance.
It is well known, that when any object is placed before the
microfcope, it mull: be fo adjulled that it may neither be too far re-
moved from, nor brought too near to the focus of the glafs, for, in
either of thofe cafes, the obje6l cannot be feen diftindly. For the
fame reafon, if any perfon is defirous to contemplate objedls through
thofe optical organs which are in the tunica cornea of the Beetle, he
will find it necellary to alIo\^' a fomewhat greater diftance between
the tunica cornea and the focus of the magnifier, fo that the focus of
each may (if I am allowed the exprelTion), become united in
one poijit, as we do when two convex lenfes are placed one
before the other in a frame : and, by this means, he will fee
the obje^l multiplied feveral hundred times, by reafon of the great
* I addrcfs mjfflf here to thofe who have feme knowledge in optics.
( fis )
number of optical organs in the tunica cornea, but all wonderfully
minute ; for the fteeple of the new church in our town, the fize of
which, and its diftance from my houfe, I have mentioned elfewhere,*
when viewed through thefc optical organs, appeared no larger than
the point of a very fmall needle.
Hence, it appears, how greatly thofe perfons are miftaken who
fay, that a Beetle is blind ; and how much perfection is to be found
in the organs of fight of fo fmall and fo defpifed an animal, to fay
nothing of the other parts of its body; but which creature, whoever
fees, immediately crufhes with his foot, as loathing the fight of that
black creeping thing.
In the month of Auguft I faw, fitting on a glafs, at the backfide
of my houfe, a Fly almoft as large as a bee, which fpecies of Fly,
though not very numerous, I obferve every year in the fame place.
I diflefted the tunica cornea of both eyes of this Fly, and, on ex-
amination, I found them to be covered with a great number of
wonderfully minute hairs, which did not cover the organs of fight,
but were placed in the intermediate fpaces between them.
Moreover, I took out of the infide of the tunica cornea, that
matter or fubftance with which it was filled, in order to examine it
by the microfcope, becaufe, till that time, I never could clearly
fatisfy myfelf to what end this fubftance was created, and the
rather fo, as, upon viewing it, I judged that it confifted of a collec-
tion of threads or fibres. Upon fpreading this a little afunder, to ex-
amine it more accurately than I had before done, I faw that
all thofe particles which I had before confidered as a coUedlion
of threads or fibres, were nearly of the fame length, but one of the
ends of each fomewhat thicker than the other, and the thicker end
rounding at the extremity.
Upon repeatedly, and more carefully, examining this fpe<ftacle, I
was, to a certainty, aflured that every one of that great quantity of
* See vol. I. Eflay on the Silk-worm, page 62.
( 6Q )
particles like threads which prefented themfelves to my Ught, were
no other than optic nerves ; and that the larger and rounding ex-
tremity of each of thefe nerves was-deftined to occupy the fmall
cavity of each optical organ on the infide of the tunica cornea ; fo
that in a word, I may venture to pronounce, that every optical
organ feen in the tunica cornea is provided with its particular
optic nerve.
As to the other extremities of the optic nerves, which, being litu-
ated towards the inner part of the head, are fmaller in fize : this
muft, I think, neceflarily be the cafe, partly becaufe the tunica
cornea dilates itfelf in a fpherical form, whence it neceflarily fol-
lows, that the optic nerves as they tend towards the internal part,
muft by degrees grow fmaller, and partly becaufe the place where
they terminate muft be fmaller than the fpace within the tunica
cornea. And who knows, whether that part in which the optic
nerves fo terminate, may not be the brain itfelf, not yet difcovered ?
In order the better to fatisfy the curiofity of others on this fubject,
I placed fome of the optic nerves of this fly upon a glafs, before the
microfcope, which I delivered to the limner, in order that he might
make as accurate a drawing of them as he was able.
Fig. 2, G H ftiews two of thefe optic nerves, the part H was placed
near to, or rather within the cavity of the optical organ ; the other
end G, towards the internal part of the fly's head.
In fig. 3, at I K L are feven of thofe optic nerves, the larger ends
of which were alfo placed next the tunica cornea.
Fig. 4, M N O P Q, fliews a great number of optic ner^'es
heaped together, the upper ends of which, as feen at the letters N O
P, were placed next the tunica cornea. When thefe nerves are
feen in fuch heaps as here pictured, their true length cannot be dil-
tinguiflied, but when lying together in a fmall number, and a mo-
derate fized parcel, the light may eafily be feen through them,
they being fomewhat tranfparent. All this is fliewn in the figure.
I have in the courfe of my obfervations difcovered, that all the
1
( 70 )
minuteli particles in the fibres of filhe.s,.\\heii at roll in tlieir natural
Hate, are, as it were, contracled in various annular folds or wrinkles ;
but when put in motion or extended for any purpofe, then all thofe
wrinkles and annidar foldings are opened or linoothed, and the
fibre becomes longer.
The fame kind of annular wTinkles I alfo difcovcred in tlie optic
nenes of the fly now under conlidcration ; whence we may conclude,
that every one of thefe optic nerves is endued w ith the power of'
alternate extenfion and contraction equally -with the optic nerves in
a human eye. For it mull needs be, that when we move our eyes
from one fide to the other, their optic nerves will be more extended
than when we look flraight forwards.
Having made this obfenation, I afked the limner whether he
could follow with his eye thofo circular marks or lines in the optic
nerves, and, upon his anfwering, that he could very plainly fee them,
I defired him to imitate them as nearly as he was able in his draw-
ings, and this is to be feen in^^, 2, and 3.
Now if this fly had been dead fometime before I had differed
the eye, and taken out the optic nerves, I am very fure, that in
that cafe, I Ihould not haA^e difcerned any of thofe wrinkles
or contractions. In like manner we daily obferve in fiflies, that after
they have been dead fometime, their flefhy parts, if cut afunder,
do not become fhorter, which our people call krimpen*, and con-
fequently thofe parts of the fifli are neither fo firm, nor fo grateful
to the palate, as when they are cut afunder while the fifli is alive.
Upon difcovery of fo many wonders, and of fuch perfedion in
the eye of a fly, we are again compelled to cry out ; How little do
we know ? And if this is feen in the eye of fo large a fly, it mull
* Krimpen in Dutch lignifies to contraifl or gather up in folds, whence the phrafe to crimp
fifti is pliiiiily ilcrlvod; whidi cruel praftice fecms alfo to have been imported from Holland.
And it must be confcfled, that with all Mr. Lceuwenhock's abilities as a philofopher, he seems
not to have had much fenHbility of compaffion for the creatures which he fubjefted to his
examination.
( 71 )
be underftood, that tlie fame obtains in the fmalleli:, and which I
have {i^€n in the dillecflion of common flies.
At the time the Hmner was making thefe drawings, I took a
fmall Gnat of that fort which is not troublefome to us, having no
(ling : the head of this Gnat I cut off, in order to extradl its optic
ner\^es, but I could not, after feveral trials, fee them dillinftly.
While I was busied in this attempt, I frequently faw the brain in
the Gnat's head fin-rounded with a great many veffels, which I
judged to be blood veffels : and though it fhould feem fcareely pof-
fible to extrad; the brain from this creature's head, M-ithout dellro^'ing
the texture of the brain and its veffels, yet, I at length fucceeded to
my wiffi, and, without their being much injured, placed the ^^•hole
before the microfcope ; this I delivered to the limner, that he might
make a drawing of it, and the rather, as I had been told by a gentle-
man of eminence, that a certain perfon, whenever my difcoveries
were the fubjeft of converfation, was accuffomed to fay, that the
experiments stated by me could not poffibly be performed ; becaufe
(as that fame perfon pretended), the inffruments ufed by me, how-
ever exquifitely conftrufted, could not be at all capable of perform-
ing the dilTedlions I defcribed. But I little regard thefe malevolent
infinuations of mankind, and perhaps this very perfon is one of thofe
who would be glad, if he was able to perform the like operations.
Fig. 5, RST, reprefents the brain taken out of the head of this
Gnat, and alfo the velfels, which in part furround it, and in part
pervade the fubftance of it, as nearly as the limner could follow
them in his drawing ; for while he was employed about it, he fre-
quently declared that he could by no means reprefent in the draw-
ing all the veffels which he faw.
The flies before mentioned, have the extremities of their feet cover-
ed with an incredible number of hairy parts, by the help of which
they are better able than other flies to climb up a glafs though it be
ever fo free from impurities or irregularities, of which they might
take hold. I have therefore often placed the feet of thofe flies before
( n )
the microfcope, in order to view the means by which they can faften
thenifelves to the glafs and nin up it ; and I have, for fome years paft,
thought that I could difcover that thefe hairs, were each of them
provided with crooked parts like hooks, by the help of which they
can take the firmer hold on glafs, but which parts have never, to my
knowledge, been defcribed by any perfon, though the figures of thofe
hairs may be feen in many authors.
In further profecution of this enquiry, and revolving the fubje6l
in my mind, a thought occurred to me refpe6ting thofe large crabs,
which are fometimes brought to this town for fale, and are, as I am
informed, caught among the rocks in Norway ; but not that I would
at all compare thefe crabs to flies, or that kind of animalcule, other-
wife than by analogy, for the feet of thofe crabs are covered with
many hairs. I therefore determined to infpedl them, and examine
the hairs, particularly thofe on the hind feet ; for thofe feet are not
furnifhed with claws, or other weapons, to grafp hold of any thing
like the fore feet, but only with one flraight claw, and with many
fliort hairs.
Upon placing these hairs before the microfcope, I faw, not with-
out admiration, that many of them were provided with a double
row of parts like teeth, placed in very exad; order befide each other, in
like manner as if we were to imagine the back of a knife cut into
a double row of teeth or notches. I have caufed a drawing to be
made of one of thefe hairs, in order to fhew its wonderful formation,
which I am perfuaded is intended for this purpofe, that when the
crab is climbing up the rocks, he may be enabled by this afliflance
to fix his feet firmly on the rocks or flones.
Fig. 6, MNOPQR, reprefents this hair, in which thofe tooth-
like parts are very plainly to be feen, but only one fide of the hair
is here vifible, and thefe teeth in the middle of the hair are longer,
as from Q to P, and from P to R they grow gradually fhorter.
Fig. 7, ST, reprefents a part only of the hair, but in fuch a
pofition that the two rows of teeth in it are confpicuous.
( 73 )
Upon this fubje6l of crabs, although I have fufficiently exliibited
to the learned world, the circulation of the blood in various animals,
and have demonllrated that it is uniformly and regularly performed
after the fame manner in all, yet, as I have met with perfons who
did not hefitate to deny this to be the fadl, I will here relate my ob-
fervations on two fmall live crabs, about an inch in diameter ; and,
judging that the extremities of their two fmalleft, or hind feet,
which were very broad and thin, would be proper objedls to
difcover the circulation, I placed one of them before the micro-
fcope, and immediately faw an incredible number of particles
of blood, which appeared to be globules ; thefe, though not red,
were of a darker colour than the liquor they floated in, and they
were running along a blood veflei which might be called a vein,
with fuch fwiftnefs, and fo great was the number of particles, that
it could not ealily be conceived but by an eye-witnefs. In fa<ft, I
cannot compare the appearance of thefe round particles of blood to
any thing better than by fuppoling we were to look through a large
opening, or a window, at a' fall of fnow, violently agitated by the
wind ; nor do I remember that I ever faw the blood driven through
the veflels with fuch fwiftnefs. It was alfo a moft delightful obje6l to
behold this large blood veflel, on each fide of it, crofl'ed by fmaller
veflels, in which the blood was driven forward with equal fwiftnefs.
Upon changing the point, or place of view, I there faw the
blood in equal agitation, and in no lefs a number of veflels.
Moreover, I happened to fee a veflel in which the blood could
not proceed in its regular courfe, but yet was in continual motion
to and fro, and all within a fpace not larger than the thicknefs of an
hair; whence I concluded, that, in the fmalleft branches, where
this velfel arofe, and in which the circulation w^as completed, the
blood was ftagnated, and thence its regular courfe in this veffel
impeded.
The pleafure I derived from this fpedlacle was fo much in my
mind, that I was induced to a farther examination of the fubjecl, and
K
( r-4 )
to beftow flill more attention on it, by examining the hind feet of
many fmall live crabs. In one of thefe I faw, by the microfcope,
not only a large artery, about the fize of an hair, which, before it
came to the extremity of the foot, divided itfelf into leveral fmall
branches ; but I alfo faw a great number, both of arteries and
veins, croffing each other; and, on turning my eye a little towards the
fides of the foot, I there faw the blood poured into lb many minute
veflels, that the fubllance w hich we fliould call the tlelliy part of
the animal, lying between the Ikin or fliell of the foot, teemed
to confill of nothing but blood veflels; fo that when I Ihewed this
circulation of the blood to a certain learned phj'lician, he frequently
exclaimed, " O how wonderful is this !"
The pleafure which this objed: afforded me was the greater,
becaufe the globules of blood, driven through all the vellels, being
fewer in number, were much wider afunder than the globules
in the blood of terreflrial or aquatic animals which are of a red
colour; fo that, I am well aflured, the globules in red blood
are twenty-five times more in number than thofe, in the fame fpace,
in the blood of a crab.
After I had feveral times repeated my obfervations on thefe
minute crabs, and my fight was in a manner wearied with the
fpecflacle, however pleafing, I had a mind to fee the blood when
drawn out of the veflels, and the rather becaufe the ferum or fluid
in which the globules were fwimming, was fo very tranfparent,
that it would be impoflible to difcem the circulation without the
afliftance of thofe globules.
The artery in this crab's foot was too fmall to be opened in the
ordinary way; I therefore determined to cut off a fmall part at the
extremity of the hind foot with a pair of fcifl"ars, and then to col-
led: the blood as it firil ifllied forth, and place it before the micro-
fcope. This being done, I faw in the fmall portion of blood
which iflued from the artery, the globules of blood for fome time
continue their circular motion.
( 75 )
Moreover, I examined the artery which I had thus cut afunder,
in that part of it which was near to the animal's body, and where
it was alfo divided into many fmaller branches, in order to fee
whether the circulation was there continued, and with great pleafure
I faw, that the courfe of the blood was not interrupted, only it pro-
ceeded with a fomewhat flower motion.
Hence I plainly perceived, that when any part of a limb is cut
off, the circulation of the blood will continue in the veflels that are
not wounded, efpecially if the efFufion of blood from the veflels
which are cut afunder can be flopped. And we may alfo, from this
experiment, be well afllired, that there is no artery, which is not
throughout the whole of its courfe divided into fmaller branches,
whereby it by degrees becomes fmaller, until the very fmalleft
ramifications return back towards the heart, and conftitute what
we call veins.
A portion of the blood taken from this crab's foot I examined by
the microfcope, to difcover, as far as I was able, of how many
parts each globule of blood was compofed ; and I concluded that
each globule was compofed of fix diftind; globules, as in the human
blood : moreover, I faw that the globules of crab's blood, when
brought into conta6l, coagulated in the fame manner as the blood
in an human body, though, till this time, I had been of opinion that
the blood of fiflies would not be difpofed to coagulate, becaufe we
do not obferve any heat in it.
I expofed a portion of the thinneft part of this blood to evaporate
in the open air, in order to fee whether, in that thin part called the
ferum, Ifliould difcover any particles; and, in doing this, I faw fo
many particles, which, to my eye, appeared fpherical, that the whole
fubftance feemed compofed of them and no other, and, upon rtir-
ring the fubftance with the point of a needle, thofe particles came still
more diflin<illy into view.
Moreover, I difcovered a great number of faline particles, which,
upon the leaft application of heat, coagulated in irregular parts.
( 70 )
But in feveral places I faw a great number of faline particles lying
near together, of a more regular fliape, and having fix fides : b\it,
with all the attention T could befiow, I did not difcover a fingle par-
ticle in crab's blood refembling the figiire of our common fait ; fo
that it is plain, to me, that the fea fait does not enter into the fub-
ftance of the bodies of filhes,
I have caufed a drawing to be made of this crab, in order to
fhew the fpecies wherein I faw the circulation performed in fo
many veflels, and which is well worthy the attention of the curious.
Fig. 7, ABCDEF, reprefents this crab, and at AB and EF
are (hewn the two external joints of each hind foot, in which
I have faid the circulation can be feen in fo great a number of
fmall veflels.
I then examined the parts which to the naked eye feem hairy,
and with which hairs the joints A B and E F are covered, in order
if poffible to difcover the circulation there ; but the veflels compo-
fing thele hairy parts were fo minute and flender, that not a fingle
globule of blood could pafs through them, and confequently it was
impoffible for me to fee the circulation in thofe parts.
Of certain animalcules hred on the leaves of the JFillow, and ivhicli
prfiduce the knobs or excrejcences frequently J'een on thoj'e leaves.
X. HERE is a fort of Willow in this country, the leaves of which
are of a deeper green, and of a larger fize than others of that tree ;
thefe Willows are for the moll part planted for the fake of their
young fhoots, which are ufed in hufbandry, and gardening for bind-
ing hedges, fences, and branches of trees together, by reafon that
they are very flexible, and at the fame time very tough; they are
therefore called by us Zeem-teenen, which may be exprefl'ed in
Englifh, by the words leathery twigs.
Upon the leaves of thefe Willows, I have often obferved certain
knobs or ritings, and having gathered fome of thofe leaves, and
opened the knobs, I at feveral times found that they contained
more than one kind of worm or maggot; but none of thofe I at
firll faw, appearing to be fiill grown, I opened fome others of the
knobs very gently, and, where I faw a maggot inclofed, I flopped
up the opening I had made, and put the leaf into a glafs tube,
that the animal inclofed might there perfed: its growth, and
undergo its change of Itate : this however I did not fee any of
them arrive at, though at the fame time, I had obfei-ved many of the
knobs vacant, and with a fmall hole in them, through which the
maggot had ilTued, leaving the cavity within, partly filled with the
excrements it had voided.
Plate XIV. fg. 8, A B C D E, reprefents one of thefe Willow
leaves, on which are feven of the knobs or excrefcences 1 have men-
tioned : in fame of thefe a hole is to be feen, as fliewn at the letters
( 78 )
F G H ; at the letter K appears a knob, wherein, upon opening it I
found a maggot.
I alfo obferved many dead maggots lying among the knobs, and
upon learching after the caufe of this appearance, I found at length
a fmall maggot flicking clofe to one of a larger fize, which
fmaller maggot feemed to have no power of moving itfelf from
place to place, each extremity of its body, particularly the hind
part, terminating in a kind of point. This maggot, with its mfouth,
had pierced into, and was fixed on the body of the larger one ; and
from this and many other instances which I faw of the like kind, it
appeared to me, that this fmall maggot was fupported by preying up-
on the larger one ; and hence I confidered that were it not for food
drawn from thole or the like kind of maggots, thefe fmaller ones
would be dellitute of fubfirtence ; for they are not provided with
any limbs or organs by which they can faften themfelves to the
leaves of trees.
But how thefe lafl: mentioned maggots could find their way into
the internal parts of the knobs or excrefcences was ftrange, and to
me entirely undifcoverablc, otherwife than by conjedlure. I fup-
pofe, firft, that the larger maggot was produced from an egg laid by
fome fly on the leaf of the Willow, and upon its biting or gnawing
the vellels in the leaf, a liquid fubftance ifllied forth, furround-
ing the maggot on all fides, and in hardening formed the knob or
excrefcence we obfcne on the leaf: fometime afterwards another,
and a fmaller fly might place itfelf on the knob, and by means of
fome weapon or piercer, bore a hole in the knob and lay therein
an egg, from which egg, the fmaller maggot might be produced.
About the middle of July I repeated my obfervations on thefe
maggots, and found many of them almoft arrived to their full growth :
and fome aftually changed into aurelias or cryfales* : I alfo found
* The tranflator has taken the liberty to cxprefs the plural number of the word cryfalis by
this termination, inftcad of adding another s to it, witli an apoftrophe between the letters, as
is fometimes done.
( 79 )
ibme of thofe minute voracious maggots, (voracious 1 may juftly
call them, lince they prey upon a maggot not lefs than fifty times
their fize), which I judged were fo far grown, that without taking
any more food, they would foon be changed into flying animals.
I had, at firft, no doubt that thefe aurelias or cryfales were of the
fame nature as thofe of common flics, namely, that when the maggot
is about to be changed into a cryfalis, its Ikin contracts, and by fuch
contraction becomes more firm and folid, and ferves the animal for
a fliell or cafe during the progrefs to its change, and then we call it
an aurelia or cryfalis, though it be not wrapped in fuch a web or
fpun cafe, as we obferve many other flying infed:s to be ; but upon
opening thefe cryfales or aurelias, I found the maggot within them
in its original fliape, although it had lain in the aurelia llate a fort-
night. And, upon viewing thefe things by the microfcope, I found
I had been miftaken in my former opinion, for the Ihell or cafe
which I have called a cryfalis^ was neither compofed of a web nor
of the flcin of the maggot itfelf, but I was obliged to conclude, that it
was formed by a concreted fubftance ifluing from the leaf of the tree,
for it had the appearance of fibrous or branched parts, from which
there ifliied fmaller ramifications. And I did not find a cryfalis in
any of the knobs I opened, excepting in thofe which I had kept in
glafl'es : one of thefe cryfales, as it lay in the knob, is fhewn at L.
After fome weeks I obferved, that from thefe cryfales certain
blackifli flies were produced, which at their tails had fome oblong
parts formed in the nature of flings, and another fort of flies, rather
of a fmaller fize, but without any fuch appearance of flings.
Fig. 9, reprefents one of thefe flies the fame fize it appeared to
the naked eye, and at the letters C D is ftiewn that part which had
the appearance of a fling, and was two thirds as long as the ani-
mal's body. But, upon placing this before the microfcope, it did not
at all appear like a fling, for it was covered with a great number
of fmall hairs, as ftiewn in Jig. 10 at the letters A B, and no aperture
was to be difcovered in it. Whereupon I began to confider that
4
( 80 )
perhaps this was only the cafe of the real fting, and, upon opening
it, I found a fling, notched at the point like a faw, of which I have
given a drawing n\Jig. 1 1, E F.
When I liad attentively viewed this for a conliderable time, I
thought it feenied to contain another fting within it; I, therefore,
endeavoured to open it, wherein I fucceeded to my wifli, and out
of it, at the place marked E F, mfg. 11,1 took two flings, both of
the fame make ; a fmall piece of one of them is fliewn at Jig. 1 2,
G H : each of thefe was jagged like a faw.
Hence it appeared, that thofe indentings or teeth, reprefented in
fg. 11 , at E F, did not properly belong to that part, but to the ftings
enclofed in it ; and, when thofe Ilings were taken out, it appeared
neceflary to conclude, that the part which I had taken for the real
lling was, in fa6l, only a fecond cafe for the two inner ones : in this
fecond fheath, or cafe, as drawn in ^^. 13, is fliewn at I K, the
cavity wherein the two flings lay; and fartlier, in Jig. 12, another
cavity is to be fcen : all which things, put together, give reafon to
conjedlure that, in each of thefe cavities, thei-e may be con-
tained fome acrid juice of a poifonous nature.
From the foregoing obfervations, we may eafily conceive, that
thefe minute flies do not merely lay their eggs upon the furface of
the leaves, but that, with their flings, they perforate the membranes
of the leaf, and depolitc an egg in the cavity ; the maggot iflliing
from which, in biting the veffels, caufes the juices of the leaf
to iflue forth, which form around it thofe knobs, or excrefcenees,
I have defcribed.
I obferved, among the dead maggots in thefe knobs, two white
oblong particles, but fo very minute as to efcapc the view of
the naked eye ; thefe I concluded to be eggs, for there was, in
no part of them, any refemblance of a maggot, and, the next day,
two maggots iflued from them, exatlly of the fame make with thofe
M'hich I have faid preyed on the larger maggots.
After this I took one of thofe voracious maggots from the body
( 81 )
of a dead one, on which it had been feeding, and placed it on a
living maggot, into which it immediately plunged its mouth, and,
notw'ithllanding all the eiforts the other made, by extending, con-
tracting, and twilling its body, to fliake it off, it Hill remained fixed
to it. One of thefe voracious maggots, when fully grown, appeared
no larger, to the naked eye, than is fhcwn at fig. 11.
I caufed a drawing to be made, from the microfcope, of one of
the maggots I have been defer ibing, when changed into an aurelia
or cryfalis. Fig. 15, ABCDEF, reprefents this cry falls, which,
in the evening was a maggot, and, the next morning, was changed
to 'the figure here reprefented, and, in its change, had put otJ
an exceeding thin pellicle ; and in like manner as the body of it,
when a maggot, was compofed of many parts like rings, fo, when
a cryfalis, it retained the fame annular or infeded form. In this
creature, not only the feet, but every fingle joint in them, might
plainly be feen.
At the letters G C and D G, are fliewn the two horns, and though
thefe were inclofed in the fame thin membrane with the body, }'et
every joint in them could very plainly be feen, and they were fully
formed, and distinct from the bodv.
This maggot before, and for fome time after, its change, was of a
perfect white, but, after fome days, the eyes, wliich may be feen at
B and E, and each of them containing many optical organs, assumed
a dark colour, inclining to a blue.
I had many of thefe maggots, and I watched them very narrowly,
to difcover in what manner their transformation from a rpaggot to
a cryfalis was performed ; but the change, when it took place, was
made in fo fliort a time that I never could get a fight ot it.
Vol. IL
A defaipt'wn of fame fpecies of mhiiitc Infects, found in frefli
water, in a Letter to Signer Anthonio Mag/iabccM,* at Florence.
To the illustrious, learned, and famous Signor Anthonio
Magiiabechi.
XHE very obliging letter with which you have honoured me, (to
which- were added what has lately been publiflied in Italy by the
learned, containing the ciu'ious invention of incloling gunpowder in
a bag, and computing the force which fuch bag would rellli before
it burll) is come to my hands ; and I beg you to be aflured that it
was moft acceptable to me : and for the favour of your letter, as
well as the communication therein contained, I defire to return you
my grateful thanks.
In reliance on your accuftomed friendlhip, I have been induced
to impart to you my obfervations and reflexions rei'peding fome
very minute animalcules, hitherto very little noticed, which are found
in the waters of this countrv.
Being employed in fearching after certain animalcules, which I
expelled to find in thofe ditches or canals which divide our fields,
I faw various fpecies of creatures, but none of thofe which I was
then in fearch of. Amonsc thefe I obferved certain animalcules,
Avithin whofe bodies I law fo quick a motion as to exceed belief;
they were about the fize of a large grain of fimd, and their bodies
being tranfparent, that internal motion could plainly be feen<
Among other things, I faw in the body of one of thefe anhnalcules
a bright and round corpufcle, placed near the head, and inwliicha
very wonderful fwift motion w^as to be feen, confifting of an alter-
nate extenfion and contradion. This particle I concluded to be the
* Magiiabechi was at (his time Librarian to tlie Grand Duke of Tuscany : hc was not lefs
famous for his learning than his peculiarities, of which foTeral anecdotes arc related in tha
AdvcDturcr,
( 83 )
lieart, and that the rapid motion of the parts round about it, which
I obferved in this animalcule, and the motion which I had feen in
the others, proceeded from the action of the heart.
Upon obferving in one of thefe animalcules eight or nine greenifli
particles I began to think that thofe were unborn young ones ; to
afcertain which I put one of the animalcules into a little w^ater, be-
ing the quantity of five or fix drops, that I might thereby fee the
young when newly ilTued from the parent and fwimming in the wa-
ter : but the next day, finding the animal dead, I opened its body
-while lying in the water, and then I not only very plainly law molt
of the unborn young ones, but I could alio difcern the organs or
limbs provided for their ufe in fwimming.
This animalcule was of fuch a pretty ihape, that I often viewed
it with great admiration : indeed, I was fo much pleated with its
formation, that I thought larger animals viewed with the naked eye
would, in companion with this, appear rudely made.* The death
of this creature feemed to me to be caufed by want of food, becaufe
I had feen it frequently void its excrements, w^hence I concluded
that it required a large fupply of nutriment in proportion to its fize.
After this I difcovered another fpecies of animalcule, almoft of
.the fame fize with the former ones, but of entirely dilFerent make.
This animalcule had a long forked tail, and each of the forked parts
again divided into foTu- parts, which laft parts were provided with
various organs.
But obferving one of thefe animalcules, (though of the fame fpe-
cies), to appear as if the hind part of its body was formed in a very
different manner, I put two of them into a fmalJ portion of water,
in order to examine them by a microfcope of greater magnifying
* This beinj; Ihc cafe, it fceras flrangc that Mr. Lceuwcnlioek has not gl?cn a figure of this
animalcule ; from the account here given of it, and particularly the motion of its heart, rt
flioiiUl fi;'m to be of tlic fpecies railed pnlex aquaticus, or water fica, of wiiich a fiuure, as
f en through the microfcope, with a del'cription of the cre.iturcj will be found in Bjtei's
ilinploymcnt for the Microfcope.
L 2
( 84 )
power. By tlae help of this, I perceived that thofe parts near the
tail, and wliich appeared like two bunches of grapes, were in fadl,
the animal's eggs, fo placed together, that there were about three
or four eggs in breadtli, and nine or ten in length, joined to each
other, but of a roiind lluipe, at each extremity, and the wliole
bearing the appearance of a bunch of grapes.
The eggs v^liich adhered to the tail of thefe two animalcules, ex-
hibited a fmall fpot in the middle of them, and round about that fpot
a pellucid fubftance ; whereas, on the contrary, the eggs of the
other animalcule appeared to me of a greenifh colour.
The following day fome of thofe eggs, which in the middle
had tliat fpot, were miffing, and after fome hours had elapfed, all
the eggs were feparated from the tail ; at the fame time I faw a
number of the fliells of the eggs fwimming in the water and alfo
many minute animalcules of fuch a lize as might be expedled to
iflue from thofe eggs. But as all thefe animalcules, though of the
fame fize, did not exactly refemble the parent in fhape,- 1 could
not thoroughly fatisfy myfelf in regard to them.
Another animalcule I had placed in a glafs tube by itfelf, and
the third day after it being fo put, apart, its eggs began to change,
each of them being marked with a fpot, and the external parts be-
coming tranfparent. The following day, purfuing my obfervations,
"? perceived that all the eggs were feparated from the tail, and a
great number of animalcules of the fame flze and make as thofe I
had at firll difcovered fwinnning in the water, and moving them-
fclves flowly from place to place by ftriking on the water v\ith cer-
tain organs they were furnilhed with.
At fight of all thefe things, 1 was convinced that thofe animal-
cvdes which I had before obferved, proceeded from the eggs ; but, to
be more certain in this refpedt, I put the parent, with all the young
ones newly brought forth, into a clean glafs, into which I had
poured about the quantity of a cubic inch of water, in order to fee
whether in that water they would increafe in lize, and undergo any
change of figure : but, upon viewing them again the following day.
^ ( 85 )
I faw but a very few of them, and after about thirty hours from
tlie time of their being firft excluded from the eggs, I only faw
one of thefe young animalcules, which was adhering to the glafs,
and feemed a little increafed in fize. The next day I could not per-
ceive one of thefe young animalcules, upon which I began to think
that perhaps the parent, for want of other food, might have de-
voured its own offspring.
Not content with the preceding obfervations, I afterwards, at
three feveral times, caught fome of thefe animalcules which had
eggs faftened to their bodies, and placed each of them in dill:inct
glafles, that fo I might be better fatisfied as to the nature of thele
creatures.
Among thefe I had one animalcule much larger than the reH,
and an extraordinary number of eggs adhering to it. As foon as
this animalcule had let go the eggs, and the young ones excluded
from them were fwimming in the water, I killed the parent ; that
by this means- 1 might the more certainly determine in what man-
ner thefe creatures acquired their growth and increafe ; but my
glafs happening to be leaky^ and the water efcaping out of it, I
was difappointed.
Moreover, I had taken and placed apart another animalcule,
half the fize of the preceding one, which neverthelefs had eggs
fixed to its body, though not a fourth part fo many in number as
thofe on the former one. After two or three days, thefe eggs were
fo far altered, that I judged the yoimg ones would foon iifue from
them; but the next day the . animalcule was dead, and all the
lliells of the eggs were adhering to its body, though the young ones
produced from them were fwimming about in the water.
It is well known, that all the fiih in our fea or rivers which lay
eggs or fpawn, and are therefore called oviparous, are, when a
year old, able to propagate their kind, being then provided with
roes or eggs ; and that thefe eggs are, llngly taken, as large in the
fmallett filh as in the largefl of the fame Ipecies ; fo that the dif-
ference in the fize of the roes proceeds only from the greater nuni?-
( 80 )
l>cr of eggs which they contain. The fume is the cafe with refpecl
to the minute animalcules of which I am now fpeaking : for the
eggs of the fmaller animalcules were of the fame fize with thofe of
th.e larger ones, thougli the eggs of one were foiu' times more in
nmnber than thofe of the other.
Thcfe lafl; animalcules 1 placed in a glafs filled wdth water, in
which Mere fvvimming fome other animalcules of the fame kind,
which were about {even or eiglit davs old ; at which time I judged
thefe animalcules to be four times the fize they were w hen tirll
excluded from the efrcr.
On the 13th of July I had fomc few animalcules in a beer glafs
full of water, none of which had any eggs adhering to them ; but
the next morning I faw a nimiber of eggs, of a greenifli colour, on
the body of one of them ; w hereupon I took this animalcule from
the others, and put it into a glals tube, about the thicknefs of a
common goofe quill, with intent to difcovcr in what fpace of time
young animalcules would be produced from thcie eggs.
In the morning of the lOth of July, I perceived fome animal-
cules which had ilfued from the eggs, and others Hill lying within
the eggs : but whereas thefe eggs had before been joined together
in very regular order, now, on the contrary, the entire eggs and
the fliells of thofe from which young ones had ilfued, lay difperfed
in a very irregular maimer.
In the mean time I had, on the 15t]i of July, obferved another
animalcule, having the lo^er part of its body tilled with eggs,
though the day before I had not {een a tingle egg on it : this,
therefore^ I placed by itfelf in a glal's, and, on the 1 8th of July I
faw all the young animalcules come forth from the eggs, and fwim-
ming about in the water.
From thefe obfen'ations I was certain, that all thefe animalcules
brought forth their eggs in the fpace of a day or a night, and
placed them on the hind parts of their bodies, in the exact and re-
( 8; )
gular order I have mentioned, and that, after three days more, tlie
young within the eggs were perfectly formed.
Thefe laft-named animalcules did not live above three or four
days, whence I conjectured that they died for want of food."
I determined to give a drawing of one of thefe animalcules, with
the eggs adhering to its body, as nearly as the limner was able
to reprelent it ; for when I took one of thern out of the water,
none or a very few parts of it could be plainly diltinguiflicd, fo
that it was neceflaiy to make the drawing while it lay in the
water.
Plate XIV. /^. 16, ABCDEFG, exhibits this animalcule, as
it lay Avith its back next the limner. The letters CHI and E K L
reprefent four horns with which the head was furniflied.
At the letters B M and F N are to be i^een the eggs which the
animalcule, having brought forth, had placed on the outfide of its
body about this part.
AO and GP, are the forked parts of the tail, which round about
their extremities, Ihewn at the letters O P, were each again fubdi-
vided into four parts, which might have been taken merely for
hairs ; but when accurately examined, and with a good magnifier,
then each of thefe parts (marked in the figure O Q and PR) ap-
peared to be covered with a great number of wonderfully minute
particles.
When the animalcule lay in this pofition, or even with its belly
tov^^ards the limner, thofe limbs or organs Avith which it moves it-
felf in the water, could not be diftinguiflied. I, therefore, placed
it fo that its fide might come into view, and that thus the limner
might copy them to his beft in the drawing.
Fig. 1 7, exhibits, at the letters abed, thofe organs or limbs,
each of which confifis of eight parts, though they could not all be,
here fliewn ; and each of thefe is compofed of various organs, part
of which may be feen at fg. IS, at the letters e and f.
Tins animalcule did not ufe thefe limbs in the fame manner as
( 88 )
terreftrial animals ^^-]^cll have many leet, nor as tliofe in the water
do tor the moll part, that is, by moving the feet fucceflivcly one
after another ; but this creature, with great fwiftnefs, moved all its
limbs at the fame inllant, io that \\ itii a fingle llroke it moved very
quickly and made much way in the water.
Here we find another convincing proof, with how many per-
fections fo minute an animalcule is endowed, as well in regard
to the llructure of its body, as to its innate diJpofition, or the in-
flinct whereby it is pompted, when the eggs arc fully gro\S'n within
its body, to place them on the outlide of it, and to the intent (as
feems to me) to protect the eggs from being injured or devoured
by other, animalcules ; and that the young ones, when in a perfedl
Hate, are able to diicngage themfelves from the eggs. And who
can difcover all the farther perfcdiions with which fo minute and (to
us) inligniligant a creature n)ay be endowed ?
^^^hen, therefore, we lee thefe wonderful properties in fo fmall
and, to us, contemj)tib]e a creature ; and, moreover, figure to our-
felvee in imagination what farther we can fuppofe concealed in it,
can any one with reafon fuppofe that fo many perfeclions are pro-
duced fpontaneoufly, or by chance ? But we lliall be a thoufand
times nearer the truth, if we lay it down as an axiom or indifput-
able fact, that all the living creatures we behold at this day, how-
-ever minute, derive their origin from thole which were formed at
the Creation.
I have frequently declared this to be ray opinion, and fliould not
now have touched upon the fubjecl", were it not that I find, by
experience, moll men Hill adhering to the old opinion, and the
follies of antiquity, that many minute animalcules are produced
fpontaneously.
But if we fee fo much pcrfeAion, as well in the make of the body
^s in the aptitude to propagate its kind, in the animalcule of which
I have been treating, \se may, by parity of reafonlng, conclude,
that the fame perfection muft necelfarily exill in the miiiutcft filhea
( 89 )
or animalcules, even in thofe whole whole bodies are llendcrer than
thofe very {lender particles with which each of the four parts (marked
in the figure bj the letters O Q and P R) are covered. For, in a
word, the animalcule 1 Imve jull been defcribing may be confidered
as an elcpliant, if compared with the moll minute of thofe filhes
or animalcules which may be difcovered in all waters.
If it be then alked, to what end fuch exceedingly minute animal-
cules were created, no anfwer can readily be given which feems
more agreeable to the truth, than that, in like manner as we fee
conftantly, that the larger kinds of filli feed on the fmaller ; as,
for example, that the cod filli preys on the haddock and other
fmaller kinds of fifli ; the haddock again on the whiting ; thefe on
ilill fmaller fifties, and among the reft: on flirimps ; and ftirimps on
fl:ill more minute fifties ; and that this gradually prevails among
all the kinds of fifli : fo that, in a word, the fmaller are created to
be food for the larger. Again, if we confider the nature of our
fea, abounding with fifti, yet having nothing at the bottom of it
fave barren land : ftored %\'ith various fliell-filh, yet dellitute of
€very green herb ; and if we, moreover, lay it down for a truth,
that no filh can be fupported on water alone, there wiU not remain
a doubt, that the fmaller filhes are dellined, by Nature, to be the
fubfiftence of the larger.
You will excufe, illuftrious Signer, my boldnefs, in taking up
your time with my remarks, of little value, fince you can employ
yourfelf in much more ufeful fiudies than to read the trifles J
commit to paper.
Delft, in Holland,
the lOih Odober, 1099.
I remainj Sec.
A. van Lecuwenhoek.
Vol. IL M
On the ^IAGNET or LOADSTONE.
JtIaVING at feveral times examined the Loadflone, ^^■ithollt
committing my obfervations thereon to writing, I at length deter-
mined to make and note down a feries of regular obfervations on
the fubjed:.
I took two Loadrtones, each of them weighing fome pounds,
and fufpended them to a balance, in order to fee what tendency
they might have to iron : I then brought a piece of iron very near
to the Loadftone, but I did not perceive that the balance to which
it was fufpended, did at all move from its pofition.
After this I took one of the before-mentioned Loadftoncs, in or-
der to fee how much weight of iron it was capable of lifting.
The firll trial I made, \\'as with the key of my houfe door ; this
the Magnet would not lift, but after I had filed off a little of the
key from that part where the Magnet was to be applied, that by
this means the fatty fubftance, left by repeated handling on the key,
might be cleaned away, then the key adhered to the magnet. Upon
obferving this, I no longer wondered that the Loadllone, when it
was before applied to the iron, had not fhewn any attractive power,
as if it had not much virtue, becaufe I confidcred that this balance
had been put to all forts of \ifes in weighing.'
I put a piece of this Loadftone, about the fize of a filbert, into
a glafs tube, and clofed the orifice of the glafs by the help of fire.
1 then brought the Loadllone near to a fea-compafs, and I found
that the needle of the compafs was as much attracted by the Load-
ilone, as if it had been on the outfide of the glafs.
I then broke the glafs, and taking that part in which the Mag-
net was placed, I clofed both ends with a blow-pipe, leaving fo
much cavity or portion of air within, as, in my Judgment, woidd
be fufficient to keep the glafs and the INIagnet in it from finking m
( 01 )
water ; and by this proceeding I hoped to difcover, whether the
Northern part or pole (as it is called) of the Magnet would point
towards the North.
Plate XIV. fg. 19, AB C D, reprefents this glafs ; at E F is the
piece of Loadllone which I placed in the middle of the glafs, that
neither of the extremities might be deprelled in the water more
than the other. I then put the glafs into an earthen veflel filled
with rain water, and I prefently law the North pole of the Magnet
move towai-ds the Northern lide of the veflel ; yet fometimes the
glafs and the Magnet in it took a contrary diredion, but which, I
think, proceeded from hence, that as I often took the glafs
out of the water, I might, in replacing it, put the North Pole
of the Magnet higher or lower than it lliould be, and there-
fore that it might not imiformly move the glafs in the fame
dire(ilion.
I alfo befpoke fome fmall Heel needles, fuch as are ufed for fea-
compalles, and both extremities of thefe, namely, the North
and South, were rubbed with a Loadflone by a man who made it
his bullnefs to prepare fea-compafles. Thefe needles, I put into
glafs tubes, clofed at the ends, and of a fize jvift to float, and putting
them into the water, I prefently faw the extremities of the needles
tend towards the North and South ; but the leafl; particle of dufl,
or breath of air meeting the tubes did, I thought, impede their
motion.
But finding, that by reafon of the length of thefe tubes, the
Magnet very diflicultly and llowly exerted its influence on the
tubes to move them in the water, I broke the glafs again, and
prepared another of fuch a ftiape, that the Magnet might put it in
motion more fpeedily : the ends of this glafs I also clofed with a
blow-pipe.
Fig. 20, G H I K L M N O, reprefents this glafs ; the letter P
indicates the place where the Loadllone was put , and by heating-
one end of this glafs, I bent it in the direction L Af, that its dif-
M 2
( 02 )
ferent motions in the water might be more eafily dilVrngiiiflicd.
This glais 1 put into a very large and broad beer-cup, in w hich
it funk in the water as deep as the place marked K: the point
M immediately veering about to the North-eaft part of the
heavens, and as often as 1 altered its pofition, it returned to it
again.
I had alfo feveral fragments of the before-mentioned Magnet,
one of which weighed no more than five grains; others of them,
fomewhat larger. I took three of thefe fmall pieces or particles,
and prepared for them three fmall glalles of the fliape reprefented
^tjjg. -1, Q R ST, in which, at V, the particle of Loadllone is to
be feen. The part Q R was added for no other purpofe than to
keep the glafs upright in the water. Two of thcfe fmall glafles
were fo made, that no more than the part S T appeared above
the furface of the water; the third was fomewhat more ele-
vated.
Upon putting thefe glaffes into the water, the extremity or part,
T, of one of them turned itfelf towards the Weft ; and as often
as I changed its pofition either way, it refted not till it had re-
turned to its firft pofition ; and even when, with a quicker mo-
tion, I turned the cup round from the South towards the Weft, fo
that the part, T, almoft pointed towards the North, that part im-
mediately turned back to the Weft, and there refted. The fecond
glafs pointed its part, T, towards the Eaft ; and in whatever di-
reftion I moved it, it would not remain at reft, except in its firft
pofition.
I was greatly furprifed to find, in thefe experiments, that fuch
minute particles of Loadftone, clofely ftiut up in glafles, and more-
over immerfed under water, would yet point to that p;u:t of the
Heavens whereto they were inclined.*
* The nniformity of Nature's operations, in cafes analogous, will be fecn cxemplifift], on
comparing thefe appearances in the Loadftone with what has been obferved by naturalifls in
( 03 )
The third glafs being put into the fame cup with the two former,
I turned it in' various diredlions, but it did not uniformly fettle in the
fame polition; for its part, T, fometimes pointed towards the South,
fometimes towards the Well, and then would incline a little from the
Well towards the South. AVhen I firll law this, I began to con-
clude that the fragment, though broken otFfrom a Magnet, might yet
be deftitute of North and South poles, and, therefore, had no power
to put the glafs wherein it was placed in motion. Bvit foon after-
wards rejecting that idea, I thought that perhaps the North and
South poles in this fragment might lie fo as to point one of them
directly upwards and the other downwards ; and that if fo, they
could not by any means put the glafs in motion. I, therefore,
feveral times took this fmall glafs out of the water, and lliook it
up and down, that by fuch lliaking the poles or corners, if they
lay up and down, might afl'ume on horizontal polition. And, after
frequent trials, I found that at length this glafs took a certain di-
redlion, and kept that polition, in like manner as I have related of
the others.
Moreover, I took an iron key, and brought it near to the glafs,
while fwimming in the water (but fo as not to let the key touch
the water) in order to fee whether this fmall piece of Loadllone,
thus inclofed and under the furface of the water, would be put in
motion by the approach of iron : but I could not obferve the leall
motion. Neverthelefs, upon bringing a thick and long piece of
iron very clofe to the water and alfo to the glafs, the glafs in-
clined a little to one fide : the fame I alfo obferved in the larger
glafs tube, which is pictured ^t jig. IQ.-
that minute aquatic animal or infe6l, the Polype ; which, if it be divided into many pieces,
each piece will become a perfeft animal, pofleiring all the properties of the original Polype,
before divided. Mr. Baker, in his attempt towards a Natural lliiloiy of the Polype, has a
curious cffiiy refperting the divifil)ili(y of the confcious principle in that living creature,
which feems applicable to the inanimate propcvtics multiplied in this fubdivillon of the JvOad-
fione. — TuANSLAioK.
( 9* )
But the motion produced in the glafles by thefe pieces of Load-
ilone was fo feeble, that I judged if a power not equal to the
thoufandth part of a grain, had been oppofed to the fmall glalles,
it ^^'ould have given them a different direAion ; for thefe particles
of Loadftone had vciy little virtue in them, if compared with what
I have heard boalled refpecting other Loadltones.
~ INloreover, I made another glai's veffel, to contain a piece of
Loadllone ; the fhape of which vell'el is fliewn at Jig. 22, A B C D
E F G H I K, and in the cavity of tliis, at A B C 1 K, a fragment
of Loadftone was placed, as marked at L. The lengtli of this
glafs, from C to D, was almoft nine inches ; the cavity in which
part was about the thickneis of an hortc hair. I purpolcd to make
the part, D E M, with a cavity of jull fuch a tize, that by means
thereof a fmall part only of the glafs might rife above the furface
of the water : and, after three feveral trials, I made the glafs fo
to my with, that the upper part of the cavity, D E F, barely ap-
peared above the furface. The reafon why I made this glafs of
fuch a length was, partly that I might fee whether the particle of
Magnet, when fo deep under the water, would yet have power to
turn its North pole towards the North, and lb to caule the glafs
vellel to change its polition ; and partly to obfei-ve w hether, when
funk fo deep, it would be at all affected by iron brought clofe to
the furface of the water. This being done, I turned round the
part, F G, feveral times ; fometimes with a quicker and fometimes
with a flower motion ; and I always found that it would not remain
at reft until its extremity, G, pointed towards the Eaft.
I could not make this experiment in a beer-cup, by reafon of
the length of the glafs ; therefore I took a wooden veffel of that
fort which are ufed in this country to meafure charges of powder
for guns, and called by us, cardocs-dooj'en, which may be rendered
in Englifli, cartridge-boxes.
After this I made another glafs, the thinneft part of which, fimi-
Jar to what is pidured in fig. 22, at C D, was thirteen inches long:
( 05 )
into this I put a piece of Loadllone, which was half as long again
as thick, but before inclofing it I carefully examined, by the help
of a fea-compafs, in what part its North pole was fituated ; and
finding it to be, not at the extremity but rather towards the middle,
I placed the Loadllone upright on its end in the glafs. The top of
this glafs, when it was put into the water with the Loadllone in it,
fcarcely appeared above the furface, and, after moying it in feveral
directions, I found that it would not remain at reft until the North
pole of the Loadftone in it pointed to the North.
When this glafs with the Magnet in it floated in a ftate of reft on
the water, I took a piece of iron, almoft eighteen inches long, one
extremity of which I approached firft to the furface of the water,
and then to the outfide of the wooden vellel near theljottom, about
the part where the Magnet lay, in order to fee whether by this the
glafs containing the Magnet woidd be put into any new motion, but
I did not at that time perceive any.
After this I applied the fame iron, not by its end but the vi^iole
length of it, as clofcly as poffible to the wooden veftel, and immedi-
ately I perceived that the glafs inclined feme what towards it, where-
vipon I llowly moved the iron roimd the box, and faw that the Load-
ftone in the glafs, and which was fourteen inches imder water, fol-
lowed the motion of the iron, fo that in nearly a minute's time it
performed a complete revolution. By this experiment the tendency
of the Magnet was proved to be greater towards the iron than to-
wards the North part of the heavens, as appeared by its following
the motion of the iron. Tlien, after fome interval, I placed the iron
length wife, clofe to the wooden box or veflel, in order to fee whether
the Loadftone would be attracted by the iron, towards the fide next to
it, which however did not happen, for it kept its pofition unmoved,
excepting only that its North pole altered its pofition a little from
the North.
Afterwards I made another glafs, wherein I put a fragment of
Loadllone, which glafs was of the fame ftiape as that reprefented at
u
( 96 )
Jig. 21, Q R S, this I put into a common beer-cup filled with water,
and when the Magnet had turned to the North, and was at reft, I
took a round piece of iron, about an inch in diameter, and placed
it lengthwife clofe to the beer-cup, m hen 1 immediately perceived
that the glafs, with the Loadllone in it, inclined fomcwhat to the
iron ; whereupon I moved the iron, as gently as 1 could, round
about the cup, and the glafs, with the Loadftone in it, immediately
followed the motion, but without approaching nearer to the fide^of
the cup, and in about a minute's Ipace performed a complete revo-
jution.
After this I placed the iron as clofe as poflible to the cup, in
order to difcover whether the attraction between it and the Magnet
would be fufficient to move the latter from the middle to the tide of
the cup next the iron, but this did not take place though they were
left a 'whole night. From thefe things I conclude, that the attrac-
tion between the JSIagnet and the iron will fliew itfelf upon the leaft
application, fo far as to caufe the circular rotation I have mentioned,
but no farther, for very little force is required to efieel this, in com-
parifon of that which would be necellary to draw the glals, contain-
ing the Loadllone, through the water to the fide of the cup. Ne-
verthelefs, I do believe that there might be fome tendency in the
Loadtlone towards the iron, and I have no doubt that if this Load-
lione had been larger, or of Itronger power, it would have moved
to the fide of the cup next tlie iron.
Once more, I made a much fmaller glafs, of the fame fliape as
lafl mentioned, in which I put a fmall piece of Loadltone, not much
more than the weight of a grain, and I found that fmall particle of
Loadllone to produce the fame efFeel as I had before obferved in the
other pieces, and the only ditference in my obferv^ations was, that
l\\c larger the Loadlione the quicker were its motions.
On the Suhjiance of the Brain in a Turkey, a Sheep, and a
Sparrow.
IN my examination of a Turkey's Brain, I began with that part
which is called the corticle ;* this part, belides the small blood- vef-
fels and globules found in it, is compofed of a very pellucid cryf-
taJline, and (as it appears to the eye) oily fubftance, which, from its
clearnefs and tranfparency, fliould rather be called the vitreous or
glafly part, than the corticle or fhell, of the Brain. When I fpread
this into fmall particles, I perceived to ilTue from it a fmall quanti-
ty of a thin fluid, compofed of very minute globules, thirty-fix of
which would not be equal in lize to a globule of the human blood ;
this liquor, though it did not extend farther from the brain than
about the tenth part of the diameter of an hair, was yet mixed with
thofe globules. I obferved this fluid matter principally in the
Brains of thofe Turkeys which had been killed fome time, whence
I concluded that it had partly iffued from the fmall velfels of the
Brain, and perhaps that fome of thofe veflels themfelves might have
been diflblved into a fluid matter. Belides thofe fmall globules, there
were fome larger ones, of which I judged lix would be equal in
(ize to one globule of human blood; thefe two forts of globules I
judged might iflue from the minute veflels which I might have
• That is, tlie fliell or cafe, from the Latin word cortex. livLich figniCea the bark of a
tree.
Vol. II. , N
( 98 )
broken, and, that, what in the animal, when ahve, was a thin fluid,
might become folid in the veflels when cold, and exhibit the appear-
iUice of thofe globules. I alfo faw, dilperled among them, fome
other bright irregular globules of different lizes, and fome as large
as a globule of human blood, and others larger. Among, or in the
midft of this watery matter and globules, there were difperfeda
great number ot wonderfully minute blood-veffels, and these in no
greater a portion of Brain than the fize of a large grain of fand.
Many of thefe blood- veflels were fo minute that (to judge by the
eye) if one of the red globules in the blood of a Turkey > or other
bird, were to be divided into five hundred parts, not one of thele
parts could be contained in the cavity of thofe veflels. For I judged,
that if the fize of the cavity of thofe veflels fliould be confldered
as 1, the axis of one of thofe globules mull be as 8, and confe-
8 quently, if the axis of any fphere is 1, and the axis of ano-
^ ther is 8, then the proportion will be as 1 to 512; and though
C4 thefe blood-velFels were fo minute, yet their colour plainly
^ fliewed that the fubflance they contained was what gives the
ii2 blojKl its red colour. And, if I had not taken notice of the
— ' faint colour w hicl) a globule of blood, tingly taken, exhibits,
it would have been impoflible for me to know thefe to be bloods
veflels, and thus it appears that the reddifli liquid imparts to them
fome kind of colour ; this I was the more certain of, by obferving
fome of thofe vefl^els Ibmevvhat larger which aflluned a redder call.
Thefe very minute blood-veflels appeared of a deeper colour \^ here
three or four of them lay one on another, without any interjacent
fublhince. From thefe appearances, I was more firmly of opinion
than before, that the globules of blood, whence its rednefs proceeds,
are divided into fmaller parts, when they come to fuch minute vel-
fels as they cannot enter without being divided ; and I was now of
opinion, that the dark colour of that part of the Brain, called the
corticle, in which it differs from the white part, called the nicdul-
( 00 )
lary or marrowy fubftance of the Brain, proceeds from this,
tliat the greater part of it confifls of pellucid particles, which are
■fo clofely joined together, that they exhibit a glafly or watery tranf-
parency, and that the dark colour is increafed by the multitude of
blood-veflels paffing through it. I alfo obferved many very minute
particles, which I judged to be globules, about the fixth part of the
fize of a globule of human blood : thefe were not tranfparent, and
gave the Brain a darkifli colour, and refpecling them I thought
that, perhaps, they might have iflued from fome of the blood-vellels
which I had cut afunder.
We may alfo perceive that this corticle of the Brain is, in many
places, deeply mixed among the medullary parts, but w hen we come
to feparate them gently, we find, betw een the two, fo great a num-
ber of blood-vellels, that they feem to conftitute an entire mem-
brane ; and we Ihall find that this internal part has as many blood-
velfels as the corticle, or external part, of the Brain. Befides thefe
fmall blood-veflels, I obferved in the Brain other veflels fo flender
that, in my judgment, none of the before-mentioned globules,
though divided into a thoufand parts, could pafs through them. T
do not here take any notice of thofe blood-veflels as large or larger
than a hair of one's head, which in great numbers run among the
medullary parts of the Brain, and are every where again divided
into branches,
When I came to what is called the medullary fubflance of the
Brain, I obferved feveral irregular globules of different fizes, fome
of which were equal to the fize of a globule of human blood, and
fome larger, and which, as well as I could judge by my eye, for
the mofl: part confifted of a thin, tranfparent, and oily fubfliance.
Thefe globules are formed in the medullary part of the Brain (and
principally in that part where the fpinal man-ow begins), in fuch
quantities that they feem to conftitute the greatefl part of the Brain.
This great multitude of tranfjparent globules caufes the white colour,
N2
( 100 )
becaiifc all tranfparent particles, which are not fo conneded toge-
ther that the light can pafs through them in a ftraight line, and do
not conftitute as it were an uniform body, muft exhibit a white ap-
pearance to the eye, as I have fliewn in * another place. Thefe ir-
regular globules were lb clofely joined, that when I endeavoured to
feparate them, fome of them llretched out, and became twice as
long as broad, and they appeared to me joined in the manner of
net-work : upon obferving which I began to conlider whether the
fmallcit blood-veflcls, ifluing out of the corticle, might not be again
divided into fmaller branches, and many of them furround thefe
globules, or give way to them, as we see the small f horizontal vef-
ftls in fome kind af wood give way to the perpendicular veflels, and
take a circuit round the half of their circumference. This opinion
of mine, that many of thefe irregular globules arc furrounded by
fmall veflels, was confirmed, -when I faw many of the laid velTels
bright in the middle, and bearing fomething of a dark colour at the
fides ; and ftill more, when, upon breaking the globules, I found
many fmall fibrous parts which feemed to be veflels lying among
them. 1 alfo often faw parts of the medullary fubftance of the
Brain of the fame figure, as if we were to behold a fifherman's net, the
threads of which can eafily be extended any way, and that between
each fpace of the net (which fifhermen call a mefli), 'a very flexible body,
in fhape of a ball, was placed, which would aflume either a round
or an oblong form, as the net was drawn one way or the other.
And to fuch a net I compare the multitude of minute veflels in the
medullary fubftance of the Brain, and the balls to the irregular glo-
bules I have mentioned. The other parts of the medullary fub-
ftance confifted of an almofl; infinite number of excefflvely minute
globules, and a clear thin matter, which laft I conje<9:ured had
iflued from the wounded veflels, and alfo that fome of the veflels
themfelves might have been diflblved into it,
* See Vol. I. p. 184, Addition by the Tranflafor.
» This may be fcen in Vol. 1. Plate 1. fig. 1, at the Letters E E £. Translator.
( 101 )
Proceeding farther in my inquiries, I took the head of a Sheep,
and upon examining its Brain, I alfo found in the corticle,
a great number of wonderfully minute blood-veflels, in which
I could difcover the fubftance which gives the blood its red
colour ; thefe veflels alfo gave the corticle a darkifli complex-
ion. I often contemplated this incomprehenfible multitude of
exquiiitely minute blood-veflels, merely for the pleafure I took
in viewing them. For I fusv almoft all of them again divide
into branches ; and I moreover took notice of a great number
of globules, each about a fixth part tlie fize of a globule of
human blood, and which, I judged, iifued from the vell'cls which
were broken ; and 1 coiicluded, that lix of thofe globules would
join to make up one globule of blood when they palled into
larger veflels, for they were very inferior in tranfparency to the
other globules adjoining. I alfo unagined that thele globules,
of which fix would m.ake up an ordinary fized globule, when they
came to veflt-Is fo fmall as not to admit them, muft be again
divided into ftill fmaller pai-ts, and then thofe vellels would become
colourlefs. And, in order more clearly to giA-c the reader feme
idea of the incomprehenf ble flendernefs of the blood veflels wliich
are formed in the brain, I have made a computation of their flze,
judging by the eye, and by comparifon wnth a large grain of fand ;
I take it then for a certain pofition that thofe globules which tinge
our blood with a red colour are, when perfecT:, of fuch a fize, that
one hundred of them laid fide by fide, do not more than
IQO equal the thicknefs or axis of a grain of fand, and
'00 confequently, that a million of globules of blood are
1,000,000 equal to a large grain of fand. I next obfervc the blood-
•5* veflels in the Brain, refpeAing which I am certain, that
64,000,000 if one globule of blood was divided into fixty-four parts,
""" none of fuch parts could pafs through one of thofe vef-
fels ; for I Hate the diameter of one of thofe vell'els to be as i; and-
( 102 )
^ the axis of a globule of blood to be as -1 ; the rcfult is, that if
4 a grain of fand \i;as divided into fixty-four niiUions of parts, not
T- one of thofe parts could enter the orilices of the fmallctl vef-
•1- lels in the Erain, and efpocially, if the fmall particles of the
~ blood were not llexible ; but T think that the fniall particles
— of the blood arc equally tlexible with thofe globules \Nhich are
of full fize. I alfo found the corticlc of the Brain in the Sheep to
confift of a clear vitreous fubftancc, tlie fame as I have deferibed in
the Brain of a Turkey ; with this only difference, that I faw in this
fome thin white fireaks, which could not ealily be difcovered by the
naked eye, fome thinner than a hair of one's head : thefe ftreaks
I judged to be caufed by a greater collciflion than ufual, of thofe
large tranfjiarent globules \s hich caufe the medullary parts to appear
\Ahite. I abb obferved in the medullary parts fome dark ftreaks of
the colour of the corticle, which dark llreaks, I judged proceeded
only from this, that there were few or none of thofe pellucid glo-
bules in that part.
After this, I examined the white or medullary parts of the
Brain, and principally thofe which are the beginning of the fpinal
marrow ; and here I think I faw, fometimes very clearly, what 1
had not been able to diftinguifli in the Brains of Turkeys, namely,
that thofe large and tranflucid (as they appeared to the fight) oily
globules, were in a manner furrounded, or lay in the midft of, an
inexpreffible nvmiber of wonderfully minute veflels or ftreaks in the
form of net- work, mixed with fome larger ones, which were in a
ftraight direction and A'cry tranfpai-ent, caufing the Brain where
they were collefted in any quantity, to appear uncommonly white
to the eye : thefe, by feveral obfervations, appeared to me to be
about the twenty-fifth part the thicknefs of an hair, and to be of a
dark colour. The remainder of the medullary fubftancc confifted
of the fame kind of parts, as I have faid I obferved in the Brains
of Turkeys. And yet I fometimes had my doubts, whether all I
deemed to be veflels were fo in reality.
( 103 )
After this, I took the Brain of an Ox immediately after the head
was cut off, and forthwith proceeded to examine the corticle of the
Brain with all the care and attention I was able. In feveral exa-
minations of which, I thought I v^as allured that the vitreous and
very pellucid fubflance (which conftitutes the greateil; part of the
corticle), coniifted of nothing elfe than of exceffively flender ftreaks
or veffels clofely joined together; though at another time, I could
not fatisfy myfelf fo fully in that refpe(ft as I wiflied to have done.
With regard to the component parts of the corticle, I could not dif-
cern any difference from what I have before related of the
other fubjedls I examined, except that I did not here perceive lb
much fluid matter, as where the animals had been killed fome time.
The white, or medullary fubftance of the brain, I found to be of
the fame nature as I have defcribed in a Sheep. For, when I ob-
ferved the very white lines or ffreaks in the medullary part (from
whence the fpinal marrow takes its origin), I found the reafon of
its great whitenefs, to be a number of very tranfparent veffels ad-
joing to each other, which feemed to me,, formed for conveying
from the fubftance to noiu'iili and fupport the Ijjinal marrow, and in
part the nerves : the largell of thefe veffels dellined for conveying
fuch nourilhment, feemed to me, as nearly as I could judge by mv
eye, to be about the hundredth part of the thicknefs of a hair of
my beard, though at another time, I faw them much larger ; but
in this inllance, I think I happened on that part of the Brain where
thole tranfparent v-ellels v/ere the fmallell of all.
In all thefe my obfervations, it mull be underllood, that I take
no notice of the multitudes of blood veffels difperfed throughout the
]>rain, which, upon diffecling it, may be feen with the naked eye.
For tilefe are, as it were, entire rivers, when compared with the
fmall vellels I difcovered, and have been now defcribiiig, whicii
may be deemed as the fmallell brooks, channels, and ditches.
I alio examined the corticle of the Brain in Sparrows, immedi-
ately after having killed them. In thefe, I not only obferved with.
( 104 )
equal diilindlnefs, the fmall veflels of every dcfcription, as I had
feen them in the Brain of a Turkey ; but alfo as clearly and dif-
tindly as I had done in the Brain of an Ox and a Sheep, and in all
other refpects, there was no difference to be noted than between
the magnitude of a Sparrow's Brain and that of an Ox ; fo that as
before obferved, there is no difference between them (except in the
large blood veflHs), fave that the fizc in the larger animal is owing
to its being compofed of a greater number of parts. And when,
with my utmoll attention, I examined the vitreous fubllance
(othcrwife called the corticle) of the Brain, it feems to me
wholly to confill of no other parts, than an incomprehenlible mul-
titude of the minuted veffels, which adjoin fo clofely to each other,
that by their tranfparency they reprefent a glafly fubftance, when
viewed by the microfcope, and which appeared more plainly to
me in the fmall Brain of the Sparrow, than in the large one of
the Ox.
Now, though I am certain of the truth of my opinion, nor have
any fcruple or doubt refpecling the exigence of the minute veflels
I have been defcribing, I had rather it were doubted of by others,
if perhaps my fight has deceived me, but which I fee no reafon to
believe. For we fhall ceafe to doubt or wonder at the minutenefe
of thefe vcllels, if we recoiled; and duly confider the minutenefs
of thofe which the fmalleft animalcules we view mull be furnifhed
with ; or what will feem lefs wonderful, if we confider what I am
going to relate, refpeding the fmallelt veflels in our own bodies.
For being lately bufied in diflcding a human eye; in the black mem-
brane which covers the cavity of the eye, and by which the rays
of light are reflected, I faw ftreaks or veflels the fmallell that I
had ever difcovered ; and being defirous to judge of their flender-
nefs, I took a large grain of fand, the axis of which was almoft
the thirtieth part of an inch : viewing this grain of fand by the
microfcope, I judged that its axis might be divided at leaft into
330 equal parts ; and finding that eight of thofe fmall vcfleU', placed
r
C 105 )
fide by fide, would not equal -1-th part of the axis
^2^640 °^ ^^^ S'^^^'^ °^ ^^"*^' ^^ follows that the axis of
fuch a grain is 2,040 times larger than the breadth
105,600 of one of thofe fmall veffels. This number 2,04o
,584,0 '
5,280
' ' being multiplied into itfelf, to find the folid con-
tents of a body whofe axis is 2,640, the refult is
' ' more than eighteen thoufand millions : fo that
2,640 1 • /~
a large gram of fand, as before-mentioned, must
278,784,000 ][jg divided into fo many millions of parts before
4,181,760,0 r ^u /- .. i- ■ . \i
13 939 "00 ^^y °^^ tnele parts can pats into the cavity
of thofe minute veflels. And the minute vellels,
' ' ' which in part conftitute the vitreous fubftance of the
Brain, I take to be fo fmall, tliat no particle or
grain of large fand could pafs through them, unlets it were firft
divided into many millions of parts. > "-^l
With regard to the Brain of a Sparrow, I found, by many ob-
fervations, that thofe parts which are called the medullary fubllance
do, for the moft part, confift of wonderfully minute fibres or vef-
fels : and in this part I met with as many fmall blood-velfels as I
have before mentioned to have feen in the corticle. The remainder
of the white fubllance in the Sparrow's Brain did not differ from
that in the Ox, Sheep, and Turkey, as I have before mentioned,
except that the tranfparent oily globules, which were enclofed by
fome of the veflels, were not fo large in the Ox. But in the Brain
of a Sparrow which had been killed twenty-four hours, I found
thofe oily globules, as far as my eye" could judge, to be of the fame
fize as in the brain of an Ox or other animal. From thefe laft ob-
fervations, and from my former ones, I began to confider whether
that great number of lucid globules (which may be confidered to
be of an oily fubllance) were not a fluid in the veflels, or perhaps
the veflTels themfelves, which, while the animal was living, con*
tinually conveyed a fubllance for the nutriment of the fpinal mar-i-
voi.. n. , o
( 106 )
row and the ncrvt^s ; and tliat, iipon the animal's death, and the
motion of the fluids in tlie vcflels ccafing, and the parts growing
cold, they collected or coagulated into irregular globules of different
fizes, in like manner as we fee that two or three globules of blood,
lying fo near as to touch each otlier, do, upon the approach of cold,
concrete togetlier and form an irregular figure. And as often as I
revolve in my mind the fituation and figure of the medullary fub-
ftance of the Brain, it feems to be defigned by Nature to convey the
blood, which in thefe innumerable fmallefl vellels, palling through
the vitreous part of the Brain (called the corticle), is prepared and
elaborated, to the fpinal marrow : fo that moft of the minute arte-
ries which are found in the Brain, feem made only to convey the
blood to the Brain, without its being returned from thence into
the veins ; and for this intent only, namely, that the Brain may
be continually fupplicd with a frefli addition of blood, and may
provide a conllant frelli fupply of fubflance, for the fupport and
iiourifliment of the fpinal marrow and the nerves. And as to the
objeclion which fome may make, that if the blood did really pals
tlirough the Brain, it would tinge the medullary fubflance of a
Ted colour ; fiich objedlion will be found of no force, if we con-
fider that a * globule of blood, fingly taken, exhibits very little of a
red appearance ; and, therefore, when divided into its moll minute
component particles, it may appear wholly colourlefs.
Addition, by the Thanslator.
The Tranflator begs leave to fubjoin a (ew -words to this Bflay, for the
information of fuch of his readers as are not converfant In the doftrine of
folids ; and the rather, as what the author dates refpefting the minutenefs
of the vefTels in the retina of the human eye may appear, at firft fight,
utterly incredible. But it muft be remembered, that it is the folid contents
of two fpheres or globes of the fizes mentioned by the author^ and not
^leir refpe£live diameters, that are the u^eafure of his computation.
* See this explained in Vol. I. page 94.
( 107 )
Tci illuftrate this, we muft underftand, that if a grain of fand were
divided into parts (fuppofing all to be of a fpherical fliape) each of wiiich
was 'aT4?sth part of the diameter of that grain, each of fucli parts would be
capable of entering the cavities of the fmall veffels he is treating of: though,
at the fame time, the rules of arithmetic teach us, that the folid contents
of that grain would be to the folid contents of one of thofe component
parts, as 18,392,744,000 to 1. Again, he tell us, that a globule of blood
(of which a million are no more than equal to a grain of fand) muft be
divided into 64 parts before it could be received into fome of the blood-vef-
fels of the Brain ; and that a grain of fand would be equal to 64 millions
of fuch parts. But by the fame rule we fhall find, that the diameter of
each fuch part is no more than ^^o^h part of the diameter of a grain of fand.
After all, it muft be confefted, that thefe reduced fubdivifions are not to be
comprehended in idea, though not fo inconceivably minute as the other
proportions feem to intimate. — See a note on this fubjeft, taken from the
Spectator, in the IntroduQion to the Firft Volume.
O 2
.7 it)
On the Seeds found in the Fig and on Strawhcrries, with the
Author s remarks on the great fecundity of Nature in the pro-
pagatio7i of plants and animals.
J HAVE, at times, beftowed much labour in fearching after the young
plant in the feed of the Fig, but always without fuccefs ; the reafon
of which I took to be, that when Figs are packed up at the places
of their growth, in order to be exported, they are gathered before
they are ripe. At Icngtli, however, while I was in fearch after fo-
reign mites (that little pernicious infccl which finds its way into all
kinds of dried provilions, fuch as clicefe, dried fifti and bacon, and
alfo dried fruits, as Figs and Railins) I found a Fig with fcA'eral hun-
dreds of thefe animals in it, but otherwife of good tafle and full
grown, feeming to me as if it had been ripe when gathered. I was,
therefore, induced to difleft fome of the fmall feeds it contained; and,
breaking open the hard outfide Ihells of feveral of them, I took out
the entire kernels they contained, then ftripping this kernel of the
membrane furrounding it, and clearing away fome moillure which
covered the plant, I faw a complete young plant, conlifting of two
leaves, and of the part from which a young tree would in due time
Jiave proceeded.
I have cauled a drawing to be made, from the microfcope, of
the }oung plant in one of thefe feeds (of which feeds we know that
every Fig contains great numbers), becaufe I have often heard it
faid, that eating Figs in great quantities, will breed lice in the
ftomach; and that fome perfons (and among them a man of fome
eminence) have not fcrupled to alfcrt the fame in writing ; which
idle taleis certainly do no other than excite derifion, for 1 am well
allured that this notion took its rife from no other caufe than the
nniltitude of fmall grains or feeds with which all Figs abound, but
,M hicli not one man in a thoufand knows to be feeds, and Itill Jcii-,
( im )
tfeat in every one of thofe feeds there is as much perfedlon as in an
entire Fig-tree ; and, therefore, it is very probable, tliat people
comparing thefe feeds or grains in Figs, by reafon of their fmall-
nefs, with lice, firfl broached the idea that lice can be bred from
Figs.
• Plate XIV, fig. 23, ABC, reprefents the kernel or internal part,
taken out of the hard fliell of one of thofe feeds, which we obferve
in great numbers in every Fig. A B is that part of the kernel to
which the firing or ligament by which the feed received its nouriih-
ment was fixed. That part from which the root and trunk of the
tree would proceed, is fituated from A towards C ; but the leaves
of the young plant lie from C towards B. Every one of thefe
grains or feeds in a Fig is diftincl from the reft, being as it were
furrounded with its own proper membrane ; fo that we may be
certain that every feed, while in the Fig, is provided with two fti'ings
or ligaments, deftined for its nourifliment, namely, one that nou-
rilhes the hard fhell, and the other that brings nourilliment to the
kernel within the Ihell.
At ^^. 24, DEFG, is feen the young plant taken out of the
ieed of the Fig; and in this figure, EFG, denote the two leaves ;
and G D E, that part which would grow to the root and ftem or
trunk. But it muft be obferved, that tliis young plant does not
conftitute the whole kernel of this .feed, but that the young plant
(befides the membrane which furrounds it) is partly enveloped
with a certain kind of fubliancc, from which it receives fupport
and growth, until the root is grown long enough to extract nou-
rilliment from the earth. All the fpace in the figure, between
FDG, was filled with this fubllance.
Now, if we attentively confidcr and obferve the membrane which
furrounds this kernel, we Ihall not only fee a great number of cx-
celiively minute veflels, but an incredible quantity of dots or cavi-
ties in it, fo that, in a word, if it were poffible to dive into all the
bidden parts of this feed, nothing \\ ould be feen but wonders and
( no )
perfections, for no doubt this minute plant pofleflos as many per-
♦edtions as an entire tree.
When I had fteeped fome of thefe feeds in water for a few hours,
and then opened them, I could diftinguilh, as well in that part which
would produce a root as in the young leaves, a great number of vef-
fels with their divifions or cells, but as foon as the liquor evaporated,
all thofe vellels difappeared.
Fig. 25, HIK exhibits the fame plant as is fliewn in fg. 24,.
with this ditference only, that whereas the former was drawn in a
pofition to Ihew only the fides of the leaves, in this figure the plant
was so placed before the microfcope as to Ihew the breadth of the
leaves.
I am at times called upon to defend the fyllem I have advanced
refpe<fling the propagation of animals (which is often the cafe with
many eminent perfons who come to vifi.t me), and they continually
objed: to what I have delivered refpedling the abundant provifion
made by Nature in the firft rudiments of the young of each fpecies,
of which few come to perfection, whereas (fay they) Nature does
nothing in vain. Tlie anfwer I generally make to this obje<ftion is,
by obferving what multitudes of feeds are produced by trees, of
which the prcfent is a ftrong inftance. For, Avhen we fee that a
common Fig contains in it between four and five hundred feeds or
grains, and that each Fig-tree may every year produce many Figs,
and from each perfeft feed a whole tree may fpring ; and confe-
quently that a fpacc of ground planted with Fig-trees may, in one
year, produce fo many feeds as would fufficc to fow, not only an
entire kingdom, but the whole furface of the earth, and that this is
not only the cafe m ith Figs, but in every kind of tree whatfoever :
when, I fay, we continually fee thefe things, I cannot but give it
as my opinion (with due deference to better judgment) that we
ought not to call in queftion for what purpofe fuch a fuperabundant
provifion is made, but that it would become us better with reverence
to acknowledge the Omnifcicnce of the Supreme Being, who has
( 111 )
thought fit to make fuch a provifiou for the propagation of anU
mals and vegetables, tlie reafons for which order of things are
to us infcrutubie, and refpeding which we can only form con-
jedlures.
In eating Strawberries, my attention was taken by thofe little
knobs or riiings we fee on their furface, and I had no doubt tliat
each of them was a feed : to- fatisfy myfelf refpefting this, I took
one of the largeft and ripeft Strawberries, and picked out feveral
of the feeds ; then llripping them of their outward covering, I
found each of them provided with a ligament by which it had
received its growth, 1 alfo broke open the hard (liell, and found
in each feed that fubllance we may call a kernel ; from this ker-
nel I took off the membrane, and placing the plant before the
microfcope, I caufed a drawing to be made of it, in order to
Ihew what numbers of feeds we fwallow in eating only a fpoon-
ful of Strawberries ; for, cutting one of the largeft Strawberries
into four pieces, I counted in one quarter of it, fifty feeds, and
confequently, that one Strawberry was covered with two hundred
feeds ; and one of the fmaller ones I judged to haAC an hundred
and twenty.
Fig. 26, A B C D E, reprefents the plant taken out of the feed
of a Strawberry ; A B C is that part which woidd grow to a root ;
and C D E A, are the two leaves which would firft appear above
the ground.
Thefe two leaves are always moft exadlly joined to each other ;
but as, while I was taking out the plant from the feed, the leaves
parted a little afunder, I directed the limner to draw them in
that pofition, that each leaf might be the eafier diftinguilhed.
Now, if we recoiled; that a young Strawberry plant, (for I never
heard of Strawberries being propagated by fowing), does in one
year fend forth various branches (commonly called runners), which
in a proper foil conftantly ftrike good roots, and grow up to per-
( 112 )
fed plants, fo that in the fame year, many plants are produced
from a fingle one, all which in the following year bear fruit, and
each of them produces many Strawberries, each of which Straw-
berries has as many feeds as we have feen : if, I fay, we duly
confider theft things, we muft needs be allonifhed, and won-
der in filence, at the multitudes of feeds which are produced by
plants.
■*-
On the nature of the minute Fibres which compofe the fiejhy parts
of feveral Animals, and aljo of Fifhes and Infects.
IN my examination of the component Fibres of the flelh of oxen
and cows, I judged tliat each fingle Fibie was fo minute, that fifty
of them, placed together, were no more than equal in diameter to
one twenty-fecond part of an inch ; but, if we take the twentieth
part of an inch, and allow the other two parts for the membranes in
which the flefhy Fibres are inclofcd, it will amount to one thoufand
1,000 flefhy Fibres in the length of an inch, and, confe-
1,000 quently, a million of fuch Fibres, wrapped in their
1 000 000 membranes, will be comprifed in the coinpafs of a
fquare Inch. In fome of my obfervations, it appeared
to me, that about an himdred of thefe flefhy Fibres, lying clofe to-
gether with a membrane furrounding them, compofed one fmall
flclhy mufcle : at another time I faw, in an ox's tongue, three fmall
fleftiy mufcles, each of them enveloped in a membrane, lying clofe
together; and, having cut them tranfverfely,! found that the fpace
they occupied was not fo much as could be covered by a grain of
fand (one hundred of which grains, placed fide by fide, make up
the length of an inch). Now, if we fuppofe that two hundred of
thefe flefliy Fibres, inclofed in their membranes, compofe a fmall
flelhy mufcle, five thoufand of thofe fmall muscles will go to make
up the dimenfions of a fquare inch. I compared the thicknefs of
thefe flefliy Fibres with the fize of a hair taken from my wig, and
I judged that at leaft four Fibres of an ox's flefli, taken near the ribs,
were contained within the fize of one of thole hairs, and that a hair
of my beard was nine times as large as one of thofe Fibres. We
mufi; not imagine that thefe flefliy Fibres are round, but each of.
Vol. 11. P.
( lit )
them aflvimes a difltrent figure, fo as to lie together and adjoin aS
ciofely as can be imagined. This my computation of the flefliy
Fibres (as they are denominated by a certain medical gentleman in
this country), I have here fet down in order to fhew their minute-
nefs, and the rather as the fame medical gentleman fuppofes, that
thefe flethy Fibres are inferted into the orifices of the veins and
end in the arteries, and that the circulation of the blood is performed
in thelc flefliy Fibres, and he fays that he has feen valves in them ;
but thefe his obfervations a§2 not taken from the microfcDpe, but
from tlie judgment of his naked eye, fo that, doubtlefs, he miftook
an entire flefliy mufcle for a fiefliy Fibre.
Plate XV. Fig. l , is a flefliy Fibre, in which I have often ob-
ferv^ed fome foldings or inequalities, like wrinkles, as A B CD, and
others lying near them, as at E F G H, and again as at I K LM, and
in this manner, viewed by a common microfcope, they had the ap-
pearance of being compofed of globules; but a flefliy Fibre alio
appeared as at NOP Q, and this la ll appearance, I think, reprefents
truly the internal original filaments of which a flefliy Fibre is com-
pofed.
Upon feeing this, I was able to fatisfy myfelf as to the reafon
why our fingers, arms, legs, and our whole bodies, while at reft,
do not lie in a right line, but fomewhat bent, and, as it were, tend-
ing to the pofition they were placed in before we were born ; and,
moreover, I think I can aflign the reafons of the motions of our
limbs, or rather the extenfions and contracflions of our mufcles,
namely, that when a mufcle is extended the flefliy Fibres compofing
it have no wrinkles or folds, but when a mufcle is not extended,
but contracted or thicker in figure, then each flefliy Fibre is full of
w^rinkies or i'olds.
Fig. 2, ABCDEFGII is a flefliy Fibre which, by expanding
and comprefling it, in order more plahily to difcover the number of
filaments of which fo fmall a Fibre confifls, I caufed to open very
much in its component filaments, and it gave the reprefentation of
( 115 )
a vein with its ramifications : this, to the beft of my ability, I re-
prefented in the drawing. Hence it plainly appears, even more
clearly than I can exprcl's, that the flefliy Fibres are again compofed
of a great number of filaments. And at one time I faw a flelhy
Fibre, fo accurately expanded and divided, that, in a fpace a little
broader than from B to H in the figure, J faw feventy of thefe com-
ponent filaments lying together ; whence I concluded, that a flefliy
Fibre no thicker (as I have before-mentioned) than the ninth part
of a hair of my beard, contained in it an hundred filaments. I often
imagined that 1 could difcern the Fibres, or, more properly fpeak-
ing, the vefi^^ls, of which the membranes in which thefe flefliy Fi-
bres are inclofed confift : hence I gave farther fcope to my imagina-
tion, and I reafoned thus ; fince we fee that a large mufcle confills
of fo many thoufand fmaller ones, or Fibres, each inclofed within
its proper membrane, and that every one of thofe fmall flefliy Fibres
is again compofed of flill fmaller filaments, of which its internal
ftrudure confills, each of thefe filaments (one hundred of which go
to making up a fingle Fibre) must be alfo a flefliy mufcle, and may
contain v/ithin it many flill fmaller filaments, inclofed in a diflindt
membrane. For we fee that the power and wifdom of the Almighty
Creator of the Univerfe, difplayed in the formation and aflociation
of the difl'erent parts which compofe his creatures, are fo wonder-
ful and incomprehenfible, that the deeper we dive into the fecrets of
his created works, the more we are confounded and loll : efpecially
when we fee living creatures moving in the water of the fimilitude
of minute eels, as pictured at fg. 3, which yet, with all their com-
ponent: parts, are fmaller than one of the filaments of which a flefliy
Fibre is compofed ; and, neverthelefs, fo minute an animalcule mull
neceliarily be furnifhcd with a Ikin, nerves, mufcles, and other parts,
all equally perfedl as thofe in a large animal.
If any admirers of the fecrets of Nature fliould defire to follow
me in thefe my obfervations, I would advife them not to chufe for
that purpofe a hot and dry feafon, but rather a time when the air ia
P2
( 116 )
cool and moill: ; for wlien thefc fmall Fibres are divefted of their
membranes, and feparated or fplit open, to difeover their component
filaments, this operation mull be performed as expeditioully as
poffible (and even then it will often fail of fuccefs) ; for the mois-
ture of thefe tlelhy Fibres will, by reafon of their thinnefs,
quickly evaporate ; and if that happens, the filaments of which the
Fibre confills will dry up and cohere fo clofely, as to exhibit the
appearance of a fingle, imiform, and folid bright fubftance.
In my lateft obfervations refpeding the mufcle of a Hare, I
plainly faw how fome of the fieihy Fibres, which were very lliarp
at the extremities, terminated in the membrane of a mufcle ; fome
again, at the extremities, terminated in a mufcular tendon. This
mufcle I placed before a good microfcope, in order to lliew the
fame to a gentleman who was vifiting me ; but the mufcle being
very flender, the moifture of it foon evaporated, whence, in a very
lliort time, the flelhy Fibres became fo clofely joined, that I could
no. difi;in6lly fee any one of them feparately, much lefs could I
difeover the place where they were united to the tendon, or indeed
the tendon itfelf.
Thefe difcoveries induced me to repeat my former inquiries into
the nature of thofe Fibres of which Fiflies are compoled ; and,
upon examining feveral parts of the cod-filli, I judged that the
moll folid fifhy Fibres were in that part of the belly near the gills.
Thefe Fibres being diverted of their membranes, I faw in them the
fame turnings, foldings, and wrinkles, as I have before noted re-
fpeding the Fibres of flefti ; but they had not always the fame
figure ; for fometimes they appeared as fg. 4, B E CD ; at another
time, as at FG; and alfo as at HI. Upon cutting thefe Fibres
tranfverfel}^ I very plainly faw the ends of thofe multitudes of
filaments of which the infide of a tiftiy Fibre is compofed. I alfo,
but very rarely, faw, on the tranfverfe cutting of thefe fifliy Fibres,
certain very bright lines or flreaks, as at A. I debated in my mind,
whether thefe were velTels deftined for the nouriUmient of thofe
( 117 )
internal filaments or membranes, to inclofe them ; but becaufe I
very rarely had a fight of this appearance, I cannot fay much re-
fpeding it. Thefe lifliyTibres are of very different fizes, fo that I
have feen fome four times as large as others ; and in one half the
circumference of fuch a fifliy Fibre, I was well aflured, I could
count almofl an hundred filaments ; and fome of thefe fila-
ments appeared to my eyes to be divided in their longitudinal po-
rtion ; as is in fome manner reprefented between K and L ; fo that
in the circumference of one fifliy Fibre there were two hundred
filaments. And becaufe this number is great, even to admiration,
I cannot omit to make a computation of it.
To find the contents of a circle from its
"" " known circumference, the rule of Archime-
des is, as 88 is to 7, fo is the fquare of the
40,000 circumference of the circle to its contents.
And, following this rule, we fhall find the
88 )-280,OQO (3,i8i contents to be 3,181 filaments in a fingle
fifliy Fibre.
Now, who can in imagination conceive fuch an incomprehen-
iible number of filaments in one of thofe Fibres compofing the
fubflance of a fifli ? And who can tell whether each one of thefe
filaments may not be inclofed in its proper membrane, and contain
within it an incredible number of Hill fmaller filaments ?
I have alfo examined the formation of the Fibres, as well in the
bodies as in the claws of crabs, and I found them like thofe in
the cod-fifh, compofed of many fmaller filaments, and with the
like folds or wrinkles as I before noted. Afterwards I examined
the Fibres of a flirimp, and found their formation to be fimilar.
Upon diflecting the hind leg of a frog, I found that the flclli
of it was, in like manner, compofed of threads or Fibres, which
Fibres being divided afunder, I perceived that each of them was
compofed of a great number of fmall filaments. But becaufe the
circular folds or wrinkles in each of thefe Fibres were larger than
( H8 )
thofe I had feen in the component flefliy Fibres of other animals,
I caufed a portion of one of them to be drawn, as fecn through
the microfcope : this is rcprefented sit Jig. 5, A B C D. The hke
folds or wrinkles I afterwards met with in the Fibres compofing
the fmall mufcles in a lamb, taken out of the belly, near the
hind leg.
Thefe folds or wrinkles in the flefliy Fibres, not only convince mc
what is the reafon why our limbs aflumc a bent pofture when the
mufcles are at reft, but we may from hence certainly learn the
reafon why we can remain longer fitting than in a ftanding pof-
ture, and why, when fitting, we do not keep our arms and hands
fully extended or hanging down, but are always moving them
about ; for if they remained long in a ftate of reft, one mufcle
would be too much extended, and another too much contrad:ed,
which would be repugnant to the natural difpofition of the muf-
cles. For the fume reafons, when we ftand for any length of time,
we do not remain fupported on both feet, but firft raife up one
foot and then the other, fo that the fore-part of one foot at a
time touches the ground, and then the mufcles of that foot are
at reft.
I was at firft at a lofs to conceive the reafon wliy fome of the
circular folds or wrinkles in the Fibres of flcfti and fifli, as in the
figure E F G H and I K LM, they are reprefcnted ; but when we
recollect, that thefc Fibres arc not round, becaufe they lie clofely
comprefled together, then if we fuppofe one of thole Fibres fepa-
rated from the adjoining ones to be round, or in a fliort time to
aflume a round figure, we may eafily conceive how this comes to
pafs : becaufe a flefhy Fibre is compofed almoft one third part of
a watery fubftance, which being foon evaporated, the internal part
may be wrinkled or contracted in a bent or irregular form. Let
us fuppofe J?^. 6, ABODE, to rcprefent a flelhy Fibre, wliich
feparated from other Fibres, will be of a round figure, which by
the evaporation of it-s moiftuic may lofe its round lliape and . be
( no )
indented and bent inwards, as is fhewn at F ; hy which means the
folds or wrinkles which before were in flraight lines will now be-
come crooked, as appears between B and D.
To purfue my oblervations on the Fibres which compofe the fub-
ftance of animals, I endeavoured to inveftigate the nature of thofe
in a flea, confidering, that if I could difcover it in the flethy Fibres
and their filaments, we may be aflured, that the fame kind of for-,
mation prevails in all living creatures. And in this inquiry, I not
once or twice, but very often, moll clearly could fee the flefliy
Fibres in the breafl of a flea, in that part where the feet are joined
to it ; and I faw alfo in them the fame circular folds or wrinkles as
I have defcribed to be in flefliy and fifliy Fibres. Some of thefe
Fibres were thicker in the middle than at the extremities, as is re-
prcfented atfg. 7, ABCDEFGH, which is a fragment of a flefliy
Fibre taken out of the breafl: of a flea. Seeing this, I thought that
the flefliy Fibres in this minute animal, terminated in a point at the
extremities, and were there united to the membrane or tendon of
the mufcle, as I have mentioned refpedling the flefliy Fibres in an
ox : and I alfo faw fome of the folds or wrinkles like C F, but for
the mofl: part they were as at A B G H, and, at various times, I
thought I faw that thefe Fibres were compofed of many fmaller
Fibres or filaments.
I continued my obfervations, by examining the flcfli taken out of
the feet of a flea, and I faw no difl'erence between the formation
and figure of the Fibres taken out of the breafl; and the feet, and
I faw more than twelve of fuch Fibres in the foot of a flea joining
to each other, and alfo many fmaller Fibres in which I could not
diftinguifli the folds or wrinkles : thefe laft I took to be exceeding
fmall blood-vcflels and nerves.
I alfo took the flefli out of the feet of fmall flies and faw the
flelhy Fibres in them to be formed in the fame manner as before-
mentioned.
The Fibres which compofe the fubflance of a whale, I alfo
( 120 )
found to be each Inclofed in a membrane, and to be compofed of
Hill fmaller filaments ; and with regard to the lize of thel'e fifliy
Fibres, each tingle Fibre M'as no larger than in the fmaller fifli ;
and indeed I have feen the Fibres in feme cod-filh, eight times the
fize of thofe in a whale.
I alfo examined the component Fibres in the flefli of a moufe, a
ealf, and a hog, and found their formation to be the fame as be-
fore defcribed, namely, each furrounded with a particular mem-
brane, and compofed of fmaller filaments : the Fibres in the fleth
of all thefe animals was nearly of the lize I have before laid down,
fo that I may fay, the flefhy Fibres compoting the body of an
ox, are not, iingly taken, larger than thofe which go to the fub-
iiance of a moufe, though, as I have computed, the one animal is
thirty thoufand times the lize of the other.
4s-
On the Scales wJiich cover the fur/ace of the Jkin of the human
body, and on the formation of the Bones.
J. HE external lurface of our bodies is covered with minute parti-
cles, which may properly be denominated Scales, placed in regular
order befide each other, but fo minute that two hundred, or two hun-
dred and fifty of them may be covered by a common grain of fand,
and, viewed by an ordinary microfcope, they appear as in Plate XY.
fig. 8, H. Many may wonder at the denomination of Scales, and
confider that word as only applicable to the covering of Mies.
But I fee no reafon why we fliould not affign that name to thofe I
am now defcribing, as well as to the external covering of a trout or
a carp, or even of a fmelt, although thefe lall are more than an
hundred times lefs than thofe of a trout or carp ; in lilce manner
thofe particles covering our own bodies, though fome thoufand times
lefs than a fmelt's, may properly be denominated Scales, fmce they
are fuch in fadt, and anfwer the fame purpofe on our bodies as
Scales do on thofe of fillies. Thefe Scales on our bodies, as I have
before faid, lie in exadl order befide each other, in like manner as
in fiflies ; and I not only could fee that their fhape was a figure of
live fides, but in many I could perceive parallel borders or ridges,
which I imagined denoted the growth or increafe of each Scale, as
by a microfcope we obfei-ve in fiflies. A drawing of one of thefe
Scales, as viewed by the microfcope, is given ^.tfg. 9, K ; and this
I judged to be a perfed Scale, which had been fixed in the fkin
at the end O P, and this part I always found to be not fo broad as
Vol. IL Q
( 122 )
llie upper end. Many other Scales were not fo long as this, nor
their lides lb Imooth, and thele 1 judged I had pulled or broken
off the Ikin before they had come to their perfc6l fize and growth.
Thefe Scales are wonderfully thin, for I judged them to be
twenty-five times broader than thick ; and I alfo perceived, that
they were placed in triple rows on each other ; or, in other words,
that our Ikin is covered with three layers of them, for only one
third part of each Scale is vifible to the eye, and under it are, at
leali, two other Scales, which are covered by it, as appears at
fig, 11, M, the part of which marked 1, 2, 3, 4, is only vifible, the
remainder being covered by other Scales. That part of the Scale
marked 3, I feldom perceived lb lliarp pointed as here pidlured;
but as I confidered this to be one of the moft perfc<^ly formed
Scales I had met with, I copied its figure in the drawing. In
filhes we alio fee, that while their Scales arc fixed to their bodies,
only a part of them is vifible to us. But whereas, fithcs never call
their Scales, at leaft as I could ever obferve, this is not the cale
with our bodies, for I myfelf have ieen on my own body a thou-
fand Scales and vipwards feparated from the Ikin and adhering to-
gether; but when I pulled off any Scales flicking to my Ikin, and
which I conceived were newly formed, either an elRjlion of blood
followed, or a red fpot appeared. I alfo took fome Scales from the
fkin of my arm, in a place where a fear had been left on my being
let blood about twenty-five years ago, and I law many of them
lliaped as at j%, lo, L.
I obferved on many of thefe Scales certain tranfparent irregular
llreaks, which 1 have reprefented in^^. li, M, and thefe covered here
and there with round globules about a fixth part the fize of a glo-
bule of blood, and thefe are alio reprefented in the figure ; and
thefe, I fuppofed to be occafioned by exfudations from the body left
upon the Scales. From this conftrudlion of our external Ikin, I
think, we may conclude that fleas, lice, and othei- infeds, do not
( 123 )
need much force to infert their llings, becaufe they can introduce
them between the rows of Scales, and not llrike through the fohd
fubllance of the Scales.
Thefe' my obfervations, feemed to me to prove, that there are no
particular pores in the external furfacc of our Ikins, but that the
moifture which proceeds from our bodies (particularly when we per-
lpire),may, at the fame time, ilfue in many places between each Scale,
though tlie Scales appear firmly united to each other ; and there
may be between each of the Scales fmail canals or du(fi:s through
which the moitlure may find a paflage. Now, if we recolleA
how many places there are which produce the Scales, and that in
a fpace covered by one Scale, there may be an hundred places
through which the perfpirable matter iflues ; and again, that two
hundred Scales, regularly difpofed, may be covered by a common
grain of fand, we may conclude, that there may be twenty thou-
fand pallages in our bodies for perlpiration, in a fpace covered by
a grain of fand, excepting only the places wherein the Scales are
rooted, or from whence they grow. Hence it appears, that our
bodies may be, as it were, one fingle pore throughout, while phy-
ficians are always talking of the pores of the body, as if there
were in it particular holes or orifices for that purpofe, and efpeci-
ally where they fee a Ihiall round drop of Iweat, not confidering
the efFedl of the air, and that a fmall portion ot moiliure, ilfuing
from many thoufand apertures, when preiled by the air, mull form
itfelf into a globule.
I have feen a drawing, made by a gentleman of fome eminence,
reprefenting certain furrov^s in the infide of the fingers and the hand,
and pubhflicd to the world as indicating the pores of the tkin ; but,
for my part, I never confidercd thefe furrows, either in the i^ands
•or feet, as containing particular pores or orifices in the fkin, and I
always perceived a lefs propulfion of particles from thefe furrows
than from the places round about them ; and, upon examination, we
Q 2
( 124 )
fhall find the fcalcs which cover the Ikln placed more clofely toge-
ther in thofe furrows than on the more elevated parts. And, for
fome time pall, it has been my firm opinion, that the furrows or
wrinkles on the infides of our hands and feet, are only thofe places
where the external ikin,^ by means of fpme ftraight veil'els in it, is
uncommonly clofe and compa6l, as we fee in fome trees which have
furrows or wrinkles in their bark, proceeding from the veflels of the
wood, which furrows are not made to emit any moillure from the
wood, but only, as 1 imagine, to unite the bark more clofely to the
wood. For, as our external Ikin is only made to defend the parts
within it, fo the bark of a tree is appointed for the defence of the
wood ; and as our external Ikin, when a new one is formed under
it, peels off by pieces, fo the bark of a tree, when the new bark is
formed, every year breaks off, piece by piece, unlefs the old and
new bark cohere too llrongly : and, in like manner as in our hands
and feet there is a firong cohefion of the old and newly formed Ikins,
it necefl'arily follows, that, in the place where the cohefion is ftrong-
eft, there muft be wrinkles or furrows in the Ikin.
I examined the Scales on the infide of my hand, and taken from
that thick Ikin we call a callus, and I found the Scales to be of the
lame dimenfions with thofe on the other parts of my body, but
whereas thofe are thin and tranfparent, thefe were covered with fo
many globules and ftreaks, that they appeared compofcd of globules.
But, as I have always found that not only the infides of the fingers
but all the infide of the hand emits much moifiure, I conclude, that
as the Scales on our arms and other parts of our bodies, when they
have no nourifliment fall off, fo, on the contrarj^ though the Scales
on the infide of our hands and feet may want nourifliment, they col-
lect together in great numbers, and, by the moillure of the parts,
are fo clofely glued or coagulated together, and fuch fmall fpaces left
for the tranfpiration,that what appears a thick Ikin is formed ; though ,
in reality it is., for the moft part, no more than a colletlion of Scales i '
( 125 )
and this is ftill more increafed by hard manual labour, which in-
creafes the colled:ion and cohefion of particles.
After this I examined the outward Ikin of my mouth, particu-
larly my under-lip, and found this to be alfo covered with Scales,
but fomewhat larger, broader, and thinner than thofe of the reft
of our bodies. Fig. 12, is a Scale of this defcription, being one
of the moll perfect I met with ; thefe Scales were alfo covered
with a greater number of ftreaks ; produced, as I fuppofe, in the
manner I have mentioned above ; and Hkewife with many very
tranfparent globules, which are pictured in the figure. Another
ot thefe Scales, adjoining to the former, was of the Ihape repre-
fented at fig. 13. But thefe Scales were not placed as they are
on other parts of our bodies, that is, three at leaft on each other,
which is the reafon that our Ikins appear white, (for all tranfpa-
rent particles, if laid loofe on each other, exhibit that colour ; fuch
as paper, froth, fpittle, poimded glafs, fnow, and the like) ; but,
on the contrary, the Scales on the lips, as far as I have been able
to difcover, only cover each other lightly on the edges, fo that the
flefh and the rednefs of the blood are feen through the greateft part
of each Scale, and for this reafon the inlide of the lips and mouth
are red.
After this, being defirous to inveftigate the manner of the for-
mation of the Scales on our bodies, I judged that thefe laft men-
tioned Scales, taken from the lips, would be the fittell: for that
j^urpofe, becaufe they are more eafily feparated from the Ikin be-
fore they become dried, than on the other parts of the body.
And, after repeated obfervations, I faw that almoft all of them
had in the middle a bright fpot, riling above the reft of the Scale;
which fpot I had formerly thought was caufed by accident ; and
from hence I now concluded for a certainty, that not only the Scales
on our lips, but alfo on our whole bodies, are formed, in like manner
as the Scales of fifties, of veflels, by which they are increafed in.
( 120 )
fize ; and if this is fo, what fhall we fay of the perfpirable parts of
our bodies ? I have ah-eady mentioned, that perfpiration may be
performed through the interlHces between the Scales, \\ hich mull
be in great numbers ; but the veflels compofing the Scales will
much exceed that number; for if thefe Scales are in contlant
growth, by the means of fuch veflels, then, by the continual mo-
tion of the body and of the thin juices, the perfpirable matter may be
expelled in great quantities through thefe veflels.
And, to make a computation of the almotl infinite number of
thefe minute veflels, I placed fome of thefe Scales, taken from the
furface of the flcin, near fome grains of fand, and I judged that
the diameter of thefe grains was from ten to twenty times the dia-
meter of thofe Scales; and the Scales are, as before mentioned,
placed in a triple row one over another. I will take, there-
fore, the fmallell number, and fay, as I have before done, that
23^ 250 Scales can be covered by a grain of fand. And
500 fuppofing each Scale to be compofed of 500 vefl^els,
J 25 000 then the perfpirable matter may be expelled through
125,000 paflages, within the compafs of a grain of fand.
befides the orifices or outlets it may find between the Scales.
With a fharp-pointed infcrument I took from the arm of a Negro
girl, about thirteen years of age, a fmall portion of the upper Ikin,
and tound it to confift of nothing but Scales, joined together
as I have faid of my own Ikin ; but thefe Scales were no fo large,
by reafon, as I concluded, that the girl was not come to her full
growth ; for an infant has as many Scales on its body as a grown
perfon, and they increafe with it in fize. And I am certain, that
though a perch, jack, or cod-fifli, be no bigger than a joint "of
one's finger, their bodies will have as many Scales on them as when
they are grown larger. On placing thefe Scales, taken from the
Negro girl, before the microfcope, I found them not fo tranfparent
as thofe on my own body ; and in the place on her arm whence I
( 127 )
had taken them, I faw there was left a black fpot. Thefe Scales I
conceived to be fuch as were almoll ready to fall off; for when I
attempted to take others, which were firmly fixed in the fkin, an
eifufion of blood foilow^ed. When I placed two of thefe Scales
one on another, they aflumed a blackifli colour ; and we muft not
wonder, that when viewed fingly through the microfcope they
fliould be tranfparent, and yet when on the (kin appear black, for
if ink, though very black, is placed very thin before the microf-
cope, it will only feem a little darker than common water ; and
the fame is the cafe with refped: to black filks, for if a filament of
fuch filk, as thin as what is fpun by the worm, is viewed through
t!ie microfcope, it will appear, not black, but of a dark colour and
alfo fomewhat tranfparent. But many particles, laid one on another,
although not wholly black, will appear fo to our eyes. And here-
upon, finding that the blacknefs of Negroes is only caufed by the
Scales being of that colour, I was enabled to form a better judgment
than I had before done refpeifting the appearance of children newly
born, for they are almofl always of a red colour, by reafon that
the Scales on their bodies, or only the firll rudiments of them, are
then beginning to appear ; fo that the blood is feen thi'ough the
fkin, giving it a red colour: and the fame is the cafe with Negro
children newly born, with this difference only, that they are of a
deeper crimlbn than our children. And I am certain, that as our
children, by the growth of tranfparent Scales on their bodidi, be-
come white, fo the children of Negroes, by the growth of the
Scales on their bodies become of a black colour. The only thing
that puzzled me about this Negro girl's fkin was, that on the in-
fide of her hands, and the bdttom of her feet, the Scales form ■
ing that part called a callus were quite white ; but an old lady in
this town, who formerly lived in Brazil, and to whom the girl's
grandmother had been a fervant, told me, that this girl's parents
were from Angola ; and that though all Negroes are born red, and
( i-'s )
T3Y degrees acquire a black complexion, yet the infides 'of their
bands and the foles of their feet are always white ; whence I con-
rlnded, that the Scales on their hands and feet are tranfparent.
I know that there are many men among us who think (and I
have heard fome fay fo), that the blacknefs of the Negroes proceed
from no other caufe than their bodies being rubbed with fome
kind of oil. Tor, tay they, when born they are of a red colour
like our children. But in like manner as it is impolTible to
dye the wool or hair on the body of a flieep, horfe, or other
animal, fo that it ihall retain the colour, becaufe the hairs or wool
are continually falling off; fo it is impoffible to dye thofe Scales
that cover the Ikin, fo as to remain black, becaufe they very foon
drop off. And jjerhaps alfo the I'mall veffels which compofe the
Scales on the bodies of Negroes may affume a black colour, m here-
by the Scales will appear llill blacker, as v^e fee the veffels in Ibme
of the coats of the eye are quite black, and I doubt not are fo
iormed to preferv^e the blacknefs in the coats they compofe.
Addition, by the Translator.
Thr perafal of this effay calls to my recoUeftion a paffage in one of Mr.
Leeuwonhock's Letters to the Royal Society, not inferted in his works,
but printed in the Philofophical Tranfaftions ; in which, treating of the
callus on the hands and feet, Mr. Leeuwenhoek confirms what he has here
laid down, that a callus is only caufed by great numbers of Scales heaped
on each other. And he alfo obferves, that on wafhing and afterwards wip-
ing his hands, he was furprized at the great number of Scales which con-
tinually came away. Hence we may gather the reafon why, if the hands
are ftained with any thing (fuch as the juice of Avalnut peel) which will
not immediately wafh off, the (tain in a fliort time wears away : and why,
in a long feccffion from labour, the hands become fmooth and foft, foraf-
much as the difcoloured and concreted Scales fall off, and are replaced by
new ones ol the natural colour and confiflence.
( 129 )
I HAVE made many obfen'-ations to difcover the real formation
t)f the Bones, and in my latell oblervations on the folid part of an
ox's thigh Bone, I plainly faw that it conlill:ed of four different
kinds of tubes, running lengthways in the Bone, the leall of which
are fo fmall, and lie fo clofe together, that they cannot eafily be
diftinguillied in a Bone cut tranfverfely ; and even if the Bone is
cut with the fharpeft knife that can be had, nothing will be (een
but the appearance of globules ; but if the Bone is fplit or cleft,
fomc fragments will be broken off in which thofe fn^iU tubes will
be perceived.
The next kind of tubes (fome of which are four, fome fix times
larger than the former) are likewife not eafily difcovered ; becaufe,
let the knife we cut them with be ever fo fharp, the hardnefs of the
Bone will caufe many pieces to be broken off, which, for the
greateft part, will clofe up or conceal the mouths or openings of
thofe tubes.
The third fort of tubes, which are much larger than the lafi^,
will become lb fiopped up in the cutting with a knife, that it will
be difficult to difcover their cavities ; but I have obferved thefe tubes
lying difpofed in fuch a manner, that I was well aflured a circle of
thofe tubes formed every new concretion or addition to the Bone,
almoft in the fame manner as I have laid it down in regard to the
growth of timber, by the addition of a circle or ring of tubes,
formed in the growth of the wood ; and efpecially when I faw,
that in a fmall fpace from thence, another circle of tubes was to
be feen.
The fourth kind of tubes, flill much larger than the lafi: preced-
ing, were fewer in number, fo that often, in the fpace of three or
four grains of fand, I could not fee one of them.
I have made as exadl a di-awing as poflible of a fmall jiarticle,
taken from an ox's thigh Bone, as the fame appeared to me through
the microfcopc, and which is fliewn at j^V. 14, ABCD. This
YOL. II. Il
( 130 )
tragment, to the naked eye, appeared no larger than the fpot,
fig. 15. E FG is the point of a Imall needle to which this frag-
ment of Bone was fixed.
The firll and fmallcll fort of the tubes I have been defcribing I
could not obferve in this fragment ; becaufe, when the Bone is
thus cut, the fmall tubes appear lying together in a confufed man-
ner, like u-regular globules ; the fecond fort of tubes I have repre-
fentedin the figure, and thefe often appear like dark fpots, becaufe
their orifices are ftoppcd up in cutting the Bone, and are more dif-
ficultly diliinguilhcd when the knife does not divide them accurately
by a tranfverfe feclion ; for if the fedion is ever fo little oblique,
it is impolfible to difcover them. This fecond fort of tubes are
reprefented at letters H H H.
The third fort of tubes I have reprefented at III: this third
fort I have not only feen adjoining each other in circular order,,
but alfo in a different order, in like manner as the large veflels in
wood.
The fourth fort of tubes, which are very large in comparifon
with the former ones, is pointed out by the letters KK. The
curved line L, and that at M, are cracks in the Bone, made by the
edge of the knife, which often happens, efpecially when the knife
is not ftiarp enough.
Befides the four forts of tubes before mentioned, forming length-
ways the fubftance of the Bone, I often imagined I faw fome tubes
taking a contrary courfe, and which feemed to me to proceed from
the internal part, and terminate at the furface of the Bone; and
I alfo thought that thefe were of two fizes, the leaft which I alfo
imagined, were analogous to the fmallell of thofe tubes which lay
lengthways in the Bone.
The rcafon why I could not truly perceive the tubes proceeding
from the cavity to the circumference of the Bone was, I think,
this, that thefe tubes were far dillant from each other; and, indeed,
I thought that one tube lay among the longitudinal ones, as if au
( 131 )
opening had been made there for it. And though I could not be
quite certain as to my feeing thefe tubes, I do not doubt that there
are a great number of them in the Bone ; and the rather, as I
think it is to be noted, that the membrane covering the Bone is
chiefly formed out of thefe vefTels, and that it is alfo fupported by
them. And of this we cannot doubt, when we obferve, that fome
trees have very fmall vefTels difperfed among the perpendicular vef-
fels, and by means of which the bark is chiefly compofed.
And in like manner as we cannot with certainty point out the
formation of the bark in the tree, becaufe it is formed every year
out of the horizontal vefl'els ; fo (according to my hypothefis), we
are never likely to draw any other conclufion, than that the mem-
branes covering the bones, receive their growth and nourifliment
from certain veflels which proceed from the cavity to the circum-
ference of the bone, and there continuing to grow, are changed
into thin and foft veflels, which protect the bone, in like manner
as we obferve the bark of trees are formed out of the wood, and
defend it from external injury.
I know that many think the origin and nourifliment of the bark
of trees depend upon the root ; but if it was fo, we fhould obferve
thofe parts of the bark next the root to be very thick, and towards
the upper part of the tree to grow thinner, and fpread into branches,
in like manner as we fee the arteries fpread from the heart, and the
•nerves from the brain ; whereas, in the veflels forming the bark of
trees, they are the fame in the upper parts as about the roots, and
what is more, the veflels in the bark of divers trees, and efpccially
the birch, cherry, peach, and goofeberry, do not take an upward courfe,
as in the oak, afli, elm, filbert, apple, and pear trees, but run only to
the furface round about the tree ; and as the barks of trees whofe vef-
fels mount upwards every year, increafe in thicknefs ; for when a tree
increafes in thicknefs, then the external part of the bark divides
in filfures, and the old and dead bark adheres to the new; and for
tills realbn, the older trees are, the thicker their bark, tliougli onh-
R 2
( 132 )
a fmall part of the bark is alive, and that is what is next to the tree.
But the cafe is otherwile, with regard to the bark of trees, where
the veflels forming it, take a circular courfe round the tree ; for
when the trees increafe in fize, thefe veflels cannot feparate afunder,
but break ; whereupon, the old bark is feparated from the new
and falls off, for which reafon, fuch trees have always a thin bark,
and this is plainly to be feen in the birch.
And in like manner as it has been faid, that the barks of trees
are formed and nourilhed, not from the root, but the wood, and
that for tlie fame reafon, the bark is not formed in branchings. The
fame I alfo confider to be the cafe, in the produclion and nou-
rifliment of the real fkin of our bodies, which is covered by an
upper Ikin compofed of Scales ; for having examined the Ikin of fe-
veral animals, I obferved, that in its texture it was not produced ir-
regularly, but I mufl; confefs, that the texture of the true Ikin was,
throughout, an entire uniform body ; and I alfo imagined, that all
the veflels (excepting the arteries, veins, and nerves), of which
our true Ikin is compofed, do run one among another in a Monder-
ful manner to form a Ikin which Ihall be of extraordinary ftrcngth ;
and that at length they grow thitmer and thinner, till at their ex-
tremities, they form Scales, with which the Ikin is covered, and then
thefe very thin veflels have no other termination than by being
formed into Scales, fo that each Scale confifls of as many veflels as
there were extremities compofmg the Scale, and that each Scale re-
mains united to the veflels until a new Scale is formed under it..
Qn the calcareous fubjiance tvhich is found in the excrefccnccs on the
li?nbs of gouty perfojis, ajid commonly called Chalk-stones, tvith
the Author s opinion refpeBing the pojjlhility of dijjolving the f alts
found therein ; and alj'o on the cure of the Gout, by burning with
the Moxa of the Chinefe.
J\ Relation of mine being greatly tormented with the gout, and
having made an incifion in the heel of his foot, took out thence a
quantity of that fubftance which phyficians call Calx, or Chalk, and
fome of this being put into my hands, I found, upon examination,
that it was compofed of fmall irregular particles, refembling a heap
of grains of fand : viewing thefe by the microfcope they appeared
of a very dark colour, and each particle to be compofed of a great
number of oblong and tranfparent figures, which cannot better be
defcribed than by a parcel of cuttings of horfc-hair, with each ex-
tremity terminating in a point. I judged thefe to be lb flender that
many thoufands of them would not be fo thick as a hair of one's
head. I have made a drawing of thefe, in order to £hew the pro-
portion of their length with their thicknefs, asmaybefeen 3ii fg. iQ,
A, Plate XV. 1 favv many parcels of thefe particles lying in very re-
gular order, as at B, and though I cannot fay that they were fo dif-
pofcd throughout the whole fubftance, yet I believe they were ori-
ginally formed in regular order of two, three, four, or more of them
placed together. Thefe fmall pieces of gouty Chalk I not only fpread
about, but alfo feparated fome of the above minute component parts,
and I faw fome of them lie in the pofition described at B, but many
of them without any regular order, as at C. I alfo favv foiue of
them not above half, or one third part, or a quarter the length re-
prefentcd at A, but as reprefcnted at D ; though I do not think this
( 134 )
was originally their length, but that they were the fragments of
particles which had been broken in the handling. Among them,
alfo, \'i'ere Ibme irregular particles, which I judged to be globules
of blood, mixed ^\ ith the gouty matter.
Being defirous to purfue this fubjedl farther, and to examine whe-
ther, by boiling the chalky fubftance in water, I could difcover any
acute faline particles pafs from it into the water, I procured fome
newly taken out of the finger of a gouty perfon. This Calx was
very white, and of a tough and gummy confiftence.
Upon fpreading this upon the furface of a new glafs, I obferv^ed
fome globular parts lying in a tenacious or gummy kind of fub-
llance ; they were of different fizes, the largest equal to grains of
fand, and others adjoining to them only one twenty-fifth part of that
lize. The vifcous matter was very tranfparent, mixed with many
very minute tranfparent globules and oblong faline particles, many
of which, viewed through a common magnifier, appeared like the
fragments of a man's beard of a week's growth, others ten times
thinner and one third the length ; in a word, of many fizes, as \\e\l
in length as thicknets.
Having fcattered fome of this fubftance on a very thin piece of
glafs, I placed it before the microfcope, directing the limner to make
a drawing of it as it appeared to him, in order to give the reader
fome idea of the nature of this calcareous matter, and which is re-
prefented at Jig. 17, IKLM. The whole of the globules here
fhewn, and the rcfl of the fubflance, were not altogether the fize of
a Ihiall grain of fand. In the figure is alfo to be feen the very mi-
nute faline particles I have mentioned.
I then endeavoured to diflblve tliis calcareous fubtlance in clean
rain water, and for that pvu-pofe put it into a new glafs, and ap-
plied fo flrong a fire to it that the water boiled. I then again ex-
amined it, and faw the globular parts, which were of different fizes,
and among which fome of the oblong particles before mentioned
could be diflinguifhed, adhere as firmly together as if the water had
( 135 )
never been heated. Thefe minute oblong faline particles were Ipread
in fuch quantities in the water, that I did not think any of them
had been diflblved in it.
I let this water Hand for a time, in order to fee whether the par-
ticles which gave it a whitifli colour would fmk to the bottom ; but
the water remained turbid, and when I fufFered it to evaporate, there
were fo many minute particles left, that the whole fubftance ap-
peared white.
This water, wherein I had fb boiled the calcareous matter, I kept
in my clofet during the whole winter, and then again examining it,
I fawthe thin oblong particles before mentioned (which I judged to
be fixed jalts) lying in as great abundance as if the Calx had been
newly extraded from the perfon's body.
From theie obfervations, I concluded, that this calcareous fub-
ftance, when in any part of a human body, cannot, by any medi-
cine, be diflblved.
A small quantity of this Calx or Chalk, taken from the fame per-
fon, I put into a fmall box well clofed, and kept it for fome months
in my clofet, I then put it into a new glafs, and gradually expofed
it to fo fierce a fire, that the glafs became red hot : I then perceived
that, by the force of the fire, a thin pellucid liquor was extracted,
and many globules of a yellow colour, but many of them afterwards,
uniting together, exhibited a red appearance ; but as foon as the co-
ver of the glafs, to which the thin tranfparent liquor and oil adliered,
began to cool, all the liquor coagulated in an incredible number of
faline particles, mofi; of which were twenty-five times longer than
broad, and were of various fizes, both ends terminating in points,
as repi-efented at Jig. 18, AB C.
Thebil which by the fire was extraded from this fubftance, and which
while warm was a liqviid, I faw was now changed into a folid fub-
ftance, which I concluded was certainly occafioned by the multitude
of faline particles coagulated in it : thefe particles in the oil were
( 130 )
much fmaller than the preceding ones, but for the mod part of the
fame fliape.
I placed the glafs to which thefe particles adhered in my clolet,
to fee whether the particles, when the weather was rainy and the
air damp, N\ould not ditlblve into a thin and pellucid liquor, and after
twenty-fix hours had clapfed, I faw their figures were all changed,
for they \\ere not only become fhorter but afllinied an irregular
Ihape, nor did I fee any faline particle which was not fiirrounded
with fome tranfparent liquor, and the oil itfelf was become thin and
fluid.
After a few days I again infpedled the glafs, and then I faw all
"the faline figures changed into a thin tranfparent liquid, mixed with
many fmall irregular and round particles.
But what appeared principally worthy of notice in thefe my ob-
fervations was, that among fo many faline particles there appeared
none of the fliape of our common fait, that is to fay, four-fijuare,
or whofe bafls was four-fquarc.
Upon the burnt afhes or caput mortmnn of this calcareous mat-
ter, I poured fome fair rain water, that if there were any fixed fait
in the aflics, it might be mixed with the water ; and ha^-ing \\'ell
ilirrcd the whole together, and left them to fi:and until the water
became clear, I then took a little of the water and expofed it in
my ftudy to the air, which was then damp, and foon after I faw
in it a great number of thin flat faline particles of various fizes,
which, for the in oil part, were of the ihnpe reprefented at Jig.
\0, DEF.
I twice touched this water with my tongue, and was furprifed
at the great faltnefs which fo fmail a portion of the aflies had im-
parted to the water : but the taste of this fait was not like that of
common fait, this being very aftringent. I five or fix times
breathed on this fixed fait, and then I perceived mofl: of the faline
particles become liquid, but as foon as the moifiure of my breath
was evaporated, they again concreted in irregular figures.
( ^^7 )
I fometimes obferved, upon fp reading the water very thin, a
great number of thin oblong particles gathered together, of the
fame figures as I had feen the minutest particles of the calcareous
matter when taken out of the perfon's finger ; but I thought, if
there had been more water, thofe particles would have been larger
and flat.
I often repeated thefe obfervations, to fee whether I could dif-
cover any thing in this fait bearing an affinity with our common fait,
but with all my attention, I never could difcover any particles fimilar
to thofe of common fait.
I again examined the water in which fome of the calcareous
matter had been boiled, and which had remained infufed in it a
whole winter, and though it was thick and turbid, I difcovered in
it an incredible number of minute particles, which all appeared
round, nor did I difcover any other faline figures than what are
in common rain water, except that at one time I faw two faline
figures in a place where the water had flood deeper than the back
of a knife, but was now almofl evaporated : thefe are fliewn at
Jig. 20, G and H.
Upon the whole, we may conclude, that the fait of which the
calcareous matter in the limbs of gouty people does for the mofl
part confifl, is of fuch a hard and tough fubftance, that though it
be boiled, or fuflered to remain in water a long time, the faline
particles it contains will fcarcely, if at all, liquefy or be diflblved :
and hence we may conclude, as before mentioned, that it is im-
poflible for phyficians or furgeons to diflblve, difcufs, or dilfipate
thofe knots or fwellings which arife in the joints of gouty people,
and are commonly called Chalk Stones, by any kind of plaifter or
fomentation ; but that the only thing which promifes any fuccefs
in this way, muft be by burning the part in the manner pra6tifed
by the Chinefe, who for this purpofe ufe what they call Moxa.
This is a certain preparation ufed in the Eaft, and mentioned by
Vol. II. S
( 138 )
H. Biifclioff, a writer on the fubjed:, in thefe words : — " Moxa is
" a foft woolly fubftance, prepared with great art, from a certain
" dried herb ; the name of the herb I know not, but I do not
" doubt that it is one of the moft excellent in all the world.
" No druggift or apothecary in all Europe knows the manner of
" preparing Moxa, but the art of doing it, is held in fuch eftima-
" tion by the Chinefe and Japanefe, that they will not fell the fc-
" cret to other nations at any price."
My opinion upon the fubjedt is, that Moxa is only an excref-
cence on fome fruit, like the woolly fubftance on peaches, and
fome other fruits ; (and IFilhelm ten Rhync, another writer on the
fubjedl, fays, that it is the woolly part of a leaf) and I have at
times collected divers woolly fubftances, which are found on fome
leaves and fruits, and burnt them, particularly that wool which falls
from the poplar tree ; this, at firft fight of it, I hoped would take
fire very readily, and I thought the fame of the wool produced by
the willow, about the beginning of June, which is of a more in-
flammable nature than what is gathered from the poplar. But I
do not as yet know of, nor have found any vegetable woolly fub-f
Hance, which burns with fuch facility as cotton ; therefore, I
would recommend it to thofe who are afflidled with the Gout, and
defire to try the experiment of a cure by fire, and cannot pro-
cure Moxa for that purpofe, to ufe cotton, which may be had in
plenty. I have alfo tried the experiment of burning with com-'
mon tinder made from linen ; but this burns fo fiercely, and pene-
trates fo deep, that I believe the ufe of moxa or cotton ten times,
would not burn fo deep as one fingle application of common
tinder.
( 139 )
Addition, by the Translator.
It may not be unacceptable to the reader^ to fee what has been faid on
this fubject by Sir William Temple, who was cotemporary with our author,
and one of the mofl: eminent perfons of his time. He himfelf tried the
application of Moxa in a fit of the Gout, and the follo\ving is an extraft from
his Mifcellanea, in his ElTay on the Cure of the Gout by Moxa.
" Being in the feven-and-fortieth year of my age, at the Hague, about
" the end of February, one night at fupper, I felt a fudden pain in my
*' right foot, which, from the firft moment it began, increafed fenfibly. I
" went to bed, but it raged fo much all night, that I could not fleep a wink.
" I endured it till the next morning, and then making my complaints and
" Ihewing my foot, they found it very red and angry, and to relieve my ex-
" tremity of pain, began to apply common poultices to it, and by the fre-
" quent change of them I found fome eafe, and continued this exercife all
" that day and a great part of the following night, which I paffed with very
" little reft. The morning after, my foot began to fwell, and the violence
" of my pain to affuage, though it left fuch a forenefs, that I could hardly
" fufFer the clothes on my bed, nor ftir my foot but as it was lifted.
" By this time my illnefs was concluded to be the Gout, and among many
" other friends who came to fee me, Monfieur Zulichem paid me a vifit,
*■ and in talking of my illnefs, he afked me whether I had ever heard the
" Indian way of curing the Gout by Moxa. This Moxa, he faid, was a
" certain kind of mofs that grew in the Eaft Indies ; that their way was,
" whenever any body fell into a fit of the Gout, to take a fmall quantity of
" it, and form it into a figure, broad at bottom as a two-pence, and pointed
" at top ; to fet the bottom exaflly upon the place where the violence of the
" pain was fixed, then with a fmall round perfumed match (made likewife
" in the Indies), to give fire to the top of the mofs, which burning down
" by degrees, came at length to the fliin, and burn it till the mofs was con-
" fumed to alhes. That many times the firft burning would remove the
" pain, if not, it was to be renewed a fecond, third, and fourth time, till it
'• went away, and till the perfon found he could fet his foot boldly to the
" ground and walk. This operation Monfieur Zulichem faid, lie became
*« acquainted with by the relation of feveral who had feen and tried it in the
S 2
( 1-10 )
" Indies ; but particularly by an ingenious little book written of it by a
"■ Dutch minifter at Batavia, who being extremely tormented with a lit of
«' the Gout, an old Indian woman coming to fee him, undertook to cure
" him, and did it immediately by this Moxa ; and after many experiments
" of it there, he had written this treatife of it in Dutch, for the ufe of his
" coiintrymen, and fent over a quantity of the mofs and matches to Utrecht,
*' to be fold, if any could be perfuaded to ufe them.
" I had always heard that a fit of the Gout ufed to have fix weeks at the
" leaft for its ordinary period, a delay very diftreffing to one in my fitua-
" tion, for I was at that time preft in my journey to Nimegucn, by his
" Majefty's * commands, to afiift at the treaty there. Mod of the ambaf-
" fadors from the feveral parts of Chriftendom were upon their way, one of
" my colleagues was already upon the place, and I had promifed imme-
" diately to follow. This made me ponder on Moniieur Zulichems new
" operation ; and upon reflefting how many cures have been performed
" by fire, I refolved upon making the trial, and difpatched a meffenger to
*' Utrecht to bring me fome of the Moxa, and learn the exaft method of
" ufmg it from the man that fold it, who was fon to the minifter at Bata-
" via. He returned with all that belonged to this cure, having performed
" the whole operation upon his hand, by the man's dire6Hon. I immedi-
** ately made the experiment in the manner before related, fetting the
" Moxa juft upon the place where the firft; violence of my pain began,
" which was the joint of the great toe, and where the greateft anger and
" forenefs ftill continued, notwithilanding the fwelling of my foot ; fo that
" I had never yet, in five days, been able to ftir it, but as it was lifted.
" Upon the firft burning, I found the (kin flirink all round the place ;
" and whether the greater pain of the fire had taken away the fenfe of a
" fmaller or no I could not tell ; but I thought it lefs than it was : I burnt
" it the fecond time, and upon it obfcrved the flcin about it to flirink, and
" the fwelling to flat about it more than at firft. I began to move my toe,
" which I had not done before, but I found fome remainders of pain. I
" burnt it the third time, and obferved ftill the fame effeCts without, but a
" much greater within, for I ftirred the joint feveral times at eafe ; and,
" growing bolder, I fet my foot to the ground without any pain at all,
" After this I purfued the method prefcribed by the book, and the author's
* King Clwrlcs H.
( 141 )
*' fon at Utrecht, and had a bruifed clove of garlic laid to the place that
" was burnt, and covered witli a large plaister of diapahna, to keep it
" fixed there ; and when this was done, feeling no more pain, and tread-
" ing ftill bolder and firmer upon it, I cut a flipper to let in my foot, fwel-
" led as it was, and walked half a dozen turns about the room, without
" any pain or trouble, and much to the furprize of thofe that were about
" me, as well as to my own.
" For the pain of the burning itfelf, the firft time it is fliarp, fo that a
" man may be allowed to complain : I refolved I would not, but that I
" would count to a certain number, as the bed meafure how long it lafted.
" 1 told fix fcore and four, as fafl as I could ; and when the fire of the
" Moxa was out, all pain of burning was over. The fecond time was not
" near fo fliarp as the firft ; and the third was a great deal lefs than the
" fecond. The wound was not raw as I expefted, but looked only fcorched
" and black ; and I had rather endure the whole trouble of the operation,
" than half a quarter of an hour's pain in the degree 1 felt it the firft whole
" night.
" After four-and- twenty hours I had it opened, and found a great blifter
'' drawn by the garlic, which I ufed no more, but had the blifter cut,,
" which run a good deal of water, but filled again by next night ; and
" this continued for three days, with only a plaifter of diapalma upon it :
" after which the blifter dried up, and left a fore about the fize of a two-
" pence, which healed and went away in about a week's time longer ; but I
" continued to walk every day, and without the leaft return of pain, the
" fwelling growing ftill lefs, though it were near fix weeks before it were
" wholly gone. I favoured it all this while more than I needed, upon the
" common opinion, that walking too much might draw down the humour;
" which I have fince had reafon to conclude a great miftake, and that if I
" had walked as much as 1 could from the day the pain firft left me, the
" fwelling might have left me too in a much lefs time.
" I paired that fummer at Ninieguen, without the leaft remembrance of
" v/hat had happened to me in the fpring, till about the end of SepteQiber,
" and then began to feel a pain, I knew not what to make of, in the fame
" joint, but of my other foot : I had flattered myfelf with hopes that the
" vapour had been exhaled, as my learned authors had taught me, and
" that thereby the bufinefs had been ended : this made me negleft my
( 1*2 )
" Moxa for two days, the pain not being violent ; till at laft my foot began
" to fwell, and I could fet it no longer to the ground. Then I fell to my
" Moxa again, and burnt it four times before the pain went clear away, as
" it did upon the laft ; and I walked at eafe as I had done the firft time,
" and, within fix days after, about a league, without the leaft return of
" my pain.
" I continued well till this fpring, when, about the end of Marcli, feel-
" ing again the fame pain, and in the fame joint, but of the firft foot ;
" and finding it grow violent, I immediately burnt it, and felt no more
" after the third time ; was never off my legs, nor kept my chamber a
" day. Upon both thefe laft experiments I omitted the application of gar-
" lie, and contented myfelf with a plaifter only of diapalma upon the
" place that was burnt, which crufted and healed in a very few days, and
" without any trouble.
" I have fince continued perfeflly well to this prefent June, and with fo
" much confidence of the cure, that I have been content to trouble myfelf
" fome hours with telling the ftory, which, it is poffible, may'at One time or
" other be thought worth making public, if I am further confirmed
" by more time and experiments of my own or of others. But this cure, I
" fuppofe, cannot pretend to deal with inveterate Gouts, grown habitual
" by long and frequent returns, by difpofitions of the ftomach to convert
" even the beft nourilhment into thofe humours, and the vefTels to receive
" them "
Thus far Sir William Temple : to which may be added, a remark made
by Dr. Henry Bracken, an eminent phyfician in his time : he obferves, that
the averfion men have to endure pain prevents their experiencing many
great cures which might be performed by fire ; and adds, that he knew an
inftance of an obftinate fciatica, or hip gout, cured by a refolute ufe of
caufticks : this application approaches the neareft to a£tual fire, and perhaps
the fire of Moxa may be of fo mild a nature as to be next in degree to »
rauftick.
On the nature of Stones in the Bladder, and Gravel in the Kid-
neys, and the Author s exaininatioJi of the question whether the
fame can by any means he broken or dissolved.
J\. VALUABLE friend of mine, the late eminent Constantine
Huygens, fometime before his death, did frequently, both in con-
verfation, and in his letters to me, exprefs a great defire to know
the reafon why the Stone in the bladder produces fuch great pain,
and I having the fame dcfire of enquiring into the nature of thofe
Stones, procured fome of them for my examination.
I put one of thefe Stones, which weighed about the fifty-eighth
part of a pound weight, into a new glals, to which I applied fo
great a heat, that the fait and oil were in part expelled from the
.Stone, when the glafs broke ; I thereupon put it into another glafs,
and by the application of fire, I drew olFthe remainder of the fait
and oil. Upon this I poured rain water, and I obferved that they
immediately united with the water. This mixture I suffered in part
to evaporate, and then I discovered in it an incredible number of
wonderfully minute faline figures, fo fmall indeed, that a mil-
lion of them would not equal a grain of fand ; and with all my
attention, I could not discover their exact fhape, for the water or
the particles in it impeded my view : however, I was perfuaded
they had four fides. I alfo examined fome faline particles which
adhered to the head of the glafs, and I faw many of them to be
thick and broad in the middle, and the ends terminate in a point.
I alfo examined the vefTel in which I had put a little of the fait and
oil, and here, befides the before -mentioned figures, I faw fome fii-
line particles like /^. 21 and 22, and feveral like_^o-. 23, each of
them with a rifmg on the back, and all tranfparent like cryflal.
( 1^* )
I kept this water in my ftudy for fome days, frequently looking
at it, and I always found that much of the liquid, as it feemed to
my naked eye, did not evaporate ; and at length I faw many fa-
line particles in it like fg. 23 ; but thefe, except a few, were fo
very fmall, that they could not be difcovered without great at-
tention.
Moreover, I poured rain water on the caput mortuum or aflies,
having firft pounded it fmall, in order to extract the fixed fait. I
fuffered this water in part to evaporate, and I difcovered in it an
incredible number of minute faline particles, which in many
places were collected or coagulated together in great numbers, and
yet retained their particular figures : this collection or coagulation
of particles, bore fome refemblance to the figures of fun flowers,
fo that in them I could not difcover the faline particles, unlefs at
the edges, where they reprefented the leaves of the flowers, as is
fliewn at^o-. 24. In other places the faline particles lay in an irre-
oular manner on one another.
I faw alfo many fingle particles, of the fliape fliewn at jig. 25,
all their extremities terminating in points. Upon keeping my
eye long fixed upon a place where only fome few fmall particles
of water lay, the heat which my touch occafioned, (the air be-
ing then molfl), caufed a great number of particles to arife with
one of their eiuis above the water ; but, on the application of a
little more heat, thefe newly formed particles difappcared, and with
ftill moi-e heat, fome little vapour arofe, and many of the faline
particles were changed into a tranlparent watery liquor, but foon
after all that liquor in many places was changed into irregular fa-
line particles ; thefe faline particles were fo foft, that upon breath-
ing on them they again changed into a fluid ; but when I again ap-
plied a flrong heat, I faw them to be more folid. The particles of
fait which had concreted in the fhape of fun-flovvers, and fome
others of the fame fpecies, remained unaltered, fo that I concluded
both thefe were fixed fait.
( 145 )
Farther, I drew fome blood from my finger, and mixed it with
different pails of the water wherein was that lixed fait, and I ob-
ferved, that the globules of blood from whence its rednefs pro-
ceeds, appeared as if their moili parts had been extracted by heat,
for each globule appeared of a ditFerent - lliape, fonie dat, and I
could fee that they were compofed of fmaller globules ; others
looked like dead animalcules, whofe feet difplayed themfelves, and
in a word, fo many different figures, that I cannot rehearfe
them all.
After this, I took ibme water wherein the volatile fait was dif-
folved, and mixed it alio with fome blood, and I immediately per-
ceived many of the globules of blood to be fo altered or diflblved,
that they could not be dillinguillied without great attention, fome
of them preferving their figure longer than others ; but this ap-
pearance I did not perceive, unlefs w here a very little blood was
mixed with much water.
Another of thefe Stones, in weight equal to about the twenty-
ninth part of a pound, I applied to a very llrong fire, and obferved
the volatile fait, which proceeded from it, remained fluid fo long as
it continued warm ; but when I took the black burnt part of it, it
lay divided in many fcaly parts like the coats of an onion, and that
part which was not fo divided, was the internal part of the Stone,
which preferved its round fhape, and was not larger than the head
of a large pin. This burnt fubfiance, or caput mortuum, I weighed,
and found it contained ten parts of a pound, fo that nineteen parts,
confilVmg of fait and oil, had been driven out of this Stone ; and
when I poured water on the refidue, and fuffered it to evaporate, 1
found, upon weighing, that it was reduced to eight parts. While
the fait and oil I had extracted remained warm, I colledled a fmall
portion of them, and faw that the oil, which was of a yellowifli
colour, by reafon of the great number of faliue particles in it, was
not fluid.
Vol. 11. T
( 140 )
After this, I put camphire in the water containing thefe falts,
but I tlid not perceive them mix with the water, though the cam-
phire llood in it for two days.
I afterwards poured otF the water and poured fpirits of wine
on the falts, but I did not perceive them unite with the fpirits of
wine.
In all my obfervations, I never faw any of the faline particles
in fhape like the figures of our common fait, and I will venture to
fay, that the fait which we commonly ufe \\ith our food, cannot
produce any addition to the Stone in the Bladder, unlefs it could
be proved, that fuch fait can be converted into a liony fubilance
in the body. But 1 know that many may not give credit to this,
and alledge, that though the Stones in the Bladder may, in part,
conlilt of common fait, yet by applying fire to them in the way I
have mentioned, they might aflume the different figures I have
defcribed to be in the volatile and fixed falts extracted from thence.
In order, therefore, to fatisfy myfelf and others in this refped, I
took fome common fait and put it into a new glafs, to which I
applied fo llrong a fire, that the glafs became red hot, and the fait
difiblved into water : when the glafs became cool, I broke it, and
taking out the fait, I mixed it with fair rain water, and then ob-
ferving it, I inw in the fpace of half a minute, nothing floating in
the water, except particles of common fait, but none like the fixed
or volatile fait extraAed from the Stone in the Bladder : when
this burnt lalt had fiood for fome hours, it was changed (the air
being then moitl) into a watery liquor, and upon applying fome
heat to it, nothing appeared except figures of common fait.
And fince we fee that Stones taken out of the Bladder do in part
confift of fuch a fixed fait as is produced by infufing the burnt mat-
ter in water, and which feems for a time to unite with the water,
but foon afterwards coagulates, and becomes fo hard, that though
the water is boiled, this fait will not mix with the water ; and
^Ifo tliat by fpirits of wine or camphire it cannot be difiblved ;
( 147 )
and that the volatile fait in it (for of thefe two falts the Stone in
the Bladder does for the moll part confill) when expofed to the
moill air, will not diflblve : that in the volatile fait there are par-
ticles fo fixed that they cannot be dilfolved but by the force of fire ;
I cannot, lor my part, perceive that any medicine can be found of
fufficient efficacy to diflblve or break in pieces the Stone in the
Bladder. And when we reflect on the lliarp-pointed particles of
the volatile and fixed falts which, for the greateft part, compofe
the Stone in the Bladder, we are not to wonder that thole Stones
excite fo much pain ; efpecially, if we confider the Iharpnefs of fo
many wonderfully minute faline particles, and the many nerves in
the Bladder, (for with any frefli accretion of matter new faline par-
ticles are added) which, with their Iharp points pierce and irritate
the infide of the Bladder.
I broke one of thefe Stones into fmall pieces, and examined them
by the micro fcope, when I found that thefe Stones confill of fuch
irregular parts as if we beheld a fubltance compounded of a great
quantity of grains of land. And in thefe obfervations I often per-
ceived thole wonderfully minute particles which I deemed to be falts,
and which I have faid confill of volatile fait, and which appear to
be of the fame nature with the calcareous fubfiance in the limbs of
gouty perfons. I have caufed a drawing to be made of a very
fmall particle, broken off from the interior part of one of thefe
Stones, partly to fhew the formation of the Stone, and partly to
exhibit the ^vonderfully minute and fliarp-pointed faline particles,
but which I feldom faw in fo great a number as are here Ihevvn ;
the reafon of which I take to be, that the particles of which the
Stone confifts adhere together fo very clofely.
Fig. 26, A B C D E F G H, is this fmall particle of Stone, which
to the naked eye appeared the fize of Jig. 27. B C D E F, repre-
fent the very minute faline particles which are only to be dillin-
guilhed at the edges of this fragment. The Stone from which this
piece was taken, together with feven or eight others, had been
T 2
( 148 )
fifteen years ago taken out of the Bladder of a child, after its death ;
the outfide of it was of an afli-colour, very fmooth, but under the
outfide fliell the whole Stone was as white as chalk, and, in fome
places, the faline particles of which it confilled glittered like frag-
ments of glafs.
I at different times mixed the water in which the volatile and
fixed falts taken from thefe Stones had been infuied, with a fmall
portion of blood taken from my finger, and found the globules of
blood to be as it were diflblved or feparated into minute parts by
the mixture.
An intimate acquaintance of mine, and a perfon of eminence in
this countiy, with whom I had formerly travelled, came to me in
a ftate of great pain, and complained, that now he was growing
in years he was greatly atBided with the Stone in his Bladder, and
afked me my opinion, whether any means could be devifed to dif-
folve or break it in pieces ; to which I replied, that I conceived
it to be impodible ; and I alfo told him, that he had contracted
this difeafe by his own manner of living. For, in our journies
together, he had beaded that he accuftomed himfelf to bear hun-
ger, thirfi, and cold ; and he alfo told me, that in hunting he only
held a fmall leaden bullet in his mouth, and by continually moving
it about, he could go for a whole day without drink, when others
could not difpenfe with it ; and to which I had re])lied, that while
we hold a leaden bullet in the mouth, its weight and coldnefs
caufes us to keep it continually in motion; and by the conllant
motion of the jaws, there is a continual fecretion of fpittle in the
mouth, which we fwallow, and thereby keep the throat moifi:, io
that we do not fo much require drink as other perfons, but ncver-
thelefs our bodies are not the lefs injured by the want of it. And
the moifture which is thus fvvallowed, and pafles through the
Kidneys, is very thick, and in fmall ((uantity, and more obnoxious
to the coagulation of falts and other particles of which the Stone in
( 140 )
the bladder is compofed, than if we were to drink in fufficient
quantity.
Another gentleman of eminence, who was troubled with the
Gravel, and had often been at my houfe, came to vifit me, with an
old phyfician of fome note, and brought with him a fmall box,
filled with Gravel Stones, alking me, whether I thought there was
any remedy which would diflblve fuch Gravel in the Kidneys ; but
this I pronounced was not to be found, by reafon that thefe Gravel
Stones do in great part conlill of fuch hard faline particles, that
they cannot be diflblved otherwife than by aclual fire, or very
llrong aqua fortis ; therefore, my opinion is, that we are only to
look for a remedy to prevent the further increafe or colleAion of
them ; and, I think, that to drink tea or coffee promifes much for
this purpofe, becaufe thereby much liquid palles to the Kidneys;
and further, that we fliould drink plentifully of beer, between dinner
and fupper time, and not follow the example of thofe who boafi:
that they drink very little in the day, and none at all at fupper.
In order to prove the truth of this my opinion, I put one of
thefe Gravel Stones into a glafs, and poured on it very flrong wine
vinegar : this I fet by for a whole year, in which time almoll all
the vinegar was evaporated, and, at the end of that time, I faw
the Stone remain entire. I then poured more vinegar on it, and
fet it by another whole year, when the vinegar was almoft all again
evaporated ; the Stone was then ftill entire ; but, upon fqueezing
it a little, it broke into many pieces, fome of which were more
than a thoufand times linaller than fand ; and I often faw a fmall
piece of this Stone, no larger than a grain of fand, to confill of
many fmaller particles concreted together ; and the multitude of
minute particles of which thefe Stones are compofed appeared to me,
-in this inftance, much more diltindly than I had ever leen tliem,
or could have imagined ; and the minute parts into which the Stone
was broken were yet very hard.
( 130 )
Hence we may more certainly pronounce than before, that there
is no medicine of fufficicnt efficacy to dillblvc the Stones or Gravel
in the Kidneys.
I have often heard in converfation, that medical men, and par-
ticularly furgeons, are accuttomed to forbid thole who are afflicted
with the Gravel, the iife of fome particular kinds of diet. But,
for my part, I am well allured, that there is no kind of food in
common ufe, which will not generate that calcareous matter which
in goutv perfons is called chalk Hones, and likewife Stones and
Gravel in the Bladder or Kidneys. But, in Ihort, fome phj-ficians
and furgeons talk of the efficacy of medicines in our bodies, and
alfo of the conftitution of our bodies themfelves, in much tlie fame
manner as bhnd men talk of colours.
On the nature and component parts of Gunpotvder, and the quantity
of' air produced by its explofton : together ivith the Author s fen-
timents refpeSing the Jize of great Guns, and his ohfervations on
condenjed and rarifed Air.
It has long been my opinion, that all the faline particles which
by the force of fire are elevated or driven upwards, from different
fubflances, muff be of a globular figure ; becavife by the fire they are
rendered foft, and are driven about with a very quick motion; in
which opinion T was confirmed by recolleding the ohfervations I had
formerly made on Gunpowder. And now, to repeat thofe experiments,
I provided feveral glafs veflels, which I made as clean as if they had
newly come out of the glafs-houfe ; fome of thefe as deep as the
breadth of three fingers, others of four, and others of fix. Thele I
heated, in order to expel from them all the moifl air of the atmof-
phere which we experience in this country in the autumn, and to
introduce in its place a more rarified or thinner air than that in
which we breathe. In a glafs fo prepared, 1 placed one or more
of the largell: grains of Gunpowder, flopping the glafs fo clofely as
to exclude all the moifl atmolpheric air ; and I then applied to that
part of the glafs where the Gunpow^der lay, a fufficient degree of
heat to fire the Powder. Hereupon the glafs appeared filled with
a kind of white fmoke, in which could be feen, both at the bottom
and fides of the glafs, the * charcoal and fulphur, which had en-
tered into the compofition of the Gunpow'der. When, in this
* It is generally known (hat Oiinpowdor i» compof'd of fa!tpetre, fiilpliur, and charcoal,
ill tho propo.'.ons of thrcc-fouiihs falipoiru, one eighth fiilplinr, and one eighth cliarcoal ;
the whole well pounded and mixed together, and afterwards prepared for ufe in the form of-
fmall grains, rcfcmbling feed?.
( 1^" )
experiment, two, three, or more grains of Gunpowder were put
into the glals, the eliarcoal and fulphur were dirperlbd more for-
cibly than when a linglc grain was ufed ; and I coidd plainly dif-
tinguifli the particles of the fulphur from thofe of the faltpetre, for
in fome places they lay fo thick together as to exhibit a yellow
colour. The A\hite fmoke (as it appeared to (he eye) was in fad;
the faltpetre. This I immediately brought before the view of a
good microfcope, and faw with great pleafure th^ inconceivable
number of its component particles, of an incredible minutenefs, in
a kind of circular motion, one among another ; and, to my moll
accurate infpeclion, they all appeared of a perfed: round figure,
belides feveral others which adhered to the glafs : after a Ihort
time, obferving that thefe moving particles began gradually to fub-
Cde, I placed the glafs not in an upright polition, but on its fide,
that they might not fink to the bottom among the particles of
charcoal and fulphur. When the glafs had remained in this pofi-
tion fo long that I judged all the faltpetre particles were in a Itate
of refi, I again examined them, and law with great furprize, that
almoll all thefe particles which a little time before appeared glo-
bular, or to which I could not affign any other figure than that of
globules, were now converted into hexagons, or falts of fix fides,
fome of which were very exa6lly lliaped, others more irregular
hexagons ; and many of them, I could plainly difcern, rifing in a
kind of piramidical Ihape, like a pointed diamond. AMien I ex-
amined thofe parts of the glafs where tlie particles of faltpetre lay
in confiderable numbers together, I could difcover but few of them
to be of an hexagonal Ihape, by reafon that the points of the par-
ticles (at the time they changed from globular to hexagonal figures)
touching each other, they thick fo clofely together as to exhibit,
upon the whole, only irregular figures. In another glafs I faw
(among the figures before defcribed) fome of the particles of the falt-
petre very long and thin, fome of which had the refemblance of
( 153 )
a bundle (3f arrows tied together, with their ends pointing dif-
terent ways.
Belides the foregoing obfervations, I faw, at the firll firing or
explofion of the Gunpowder, a very thin moillure in the upper
part of the glafs, which feemed to confill of globules of different
fizes ; which moill fubftance, I was well perfuaded, did for the
moft part proceed from the faltpetre, and which I fliall therefore
call oil of faltpetre, though it might perhaps be mixed with fome
of the oil of fulphur. In order more fully to fatisfy myfelf in this
refped, I put into one of the glafles fome refined faltpetre, leaving
a fmall opening at the top of the glafs, that it might not burft in
the experiment, and then applied fo ftrong a heat to it that the
faltpetre boiled very much ; my only view in this was, to examine
the vapour or moifture which arofe from the faltpetre, and to
which I have given the name of oil ; and I perceived, in the upper
part of the glafs, a large quantity of tranfparent and very fluid
matter, which, upon infpeftion, could be denominated no other
than oil. At another time, I faw this fubftance or oil fo colleAed
or run together, that it appeared like drops of water fpread irregu^
larly upon the glafs.
Not content with the preceding obfervations, I provided fome
other veflels of very thin glafs, in order to purfue my obfervations
with more dillinftnefs, and to fee if I could not get a view of the
changing of the faltpetre particles from globular to hexagonal
figures, to which intent, immediately as the Gunpowder in the
gtafs was fired, I brought the glafs before the view of the microl-
cope, and then I faw; the globular particles of faltpetre chtinge
their figure to hexagonal, and this was performed infiantaneously,
or as quick as a flafli of lightning to the eye, not in one or a few
of the particles, but all of them, as I may fay, in a moment ; and
though at the bottom of the glafs, where the greatell number of
particles fubfided after their firll motion ceafed, I faw an immenfe
number of fmall pai'ticles lying to which 1 could not afiign any
Vol. II. U
C 154 )
figure ; yet I doiibted not they were all of the fame fliape with the
former : and I was confirmed in this my opinion, by obferving now
and then a larger particle among them, which was of the fame
fliape I have mentioned. The number of thefe faltpetre particles
produced from one grain of Gunpowder was fo inconceivably great
that I dare not make a computation of them, they were more in
number than the particles of fulphur and charcoal ; and when I
figured in my imagination any given particle, the fize of a grain of
fand, to be divided into a thoufand millions of parts, I concluded
in my mind, that the particles of faltpetre, fulphur, and charcoal
contained within a grain of Gunpowder, were much more nu-
merous. Thefe obfervations were made with the greatefl diftind;-
nefs when I ufed only one grain of Gunpowder ; for when three
grains were fired together, the faltpetre blew up with it the fulphur
and charcoal, the particles of which not only rendered the view
indillinct, but alio impeded the change of the globular figures into
hexagons.
I have alfo taken notice, that if a grain of Gunpowder is fired
at the bottom as it lies, then the fulphur and charcoal it contains
•are blown up on high ; but if it is fired at the top, then but little
of the charcoal, and ftill lefs of the fulphur, are driven upwards.
Thefe obfenations caufed me to reflect on the manner in which
Gunpowder is proved amongll us, to judge whether it be of a
good quality : this is peformed by taking the quantity of a mulket
charge of Gunpowder, and placing it in as clofe an heap, of a
conical ihape, as may be, on clean white paper, and then giving
fire to it with a burning match; and if, in this operation, the
paper is neither burnt nor blackened, the Giinpowder is eftecmed
to be good. Neverthelefs, I cannot but think that much of this
depends upon the perfon who gives the fire ; for if the point of the
burning match is applied to the upper furface of the Gunpowder,
the conf.qucnce mull be, that the paper will be very much black-
ened, and alfo burnt, by reafon that the upper part of the Gun-
( 155 )
powder firft takes fire, and exerts its force on the lower part, which
is lafl kindled, whereby the fire and fmoke of this lall; part is driven
downwards : but if the perfon who gives the fire does, with a
light touch, fo apply the match that it may fire the lowell part of
the heap as foon or fooner than the upper part, it mull; follow
that the lower part of the powder will blow upwards what lies on
the upper part and fides of the heap, and this before it is fully
kindled, in confequence of which the paper will be little injured.
In a word, one man may fo fire a parcel of Gunpowder that it
will be deemed good powder, and another man may fire fome of
the fame fample in fuch a manner that it Ihall be condemned as
unferviceable ; that is, not fufficiently ftrong, or as being damp ;
for confidering that fome portion of time is required (as mull cer-
tainly be the cafe) for the fire of one grain of Gunpowder kindled
by another from beneath, to blow up the upper part of the fame
grain, much more time mull be required in a whole mulket charge
of Gunpowder for the fire of one grain to be communicated to
the others.
I have alfo turned my thoughts on obferving the firing of Gun-
powder in a clofe glafs to the following confideration, namely,
whether the motion of the faltpetre particles and the fire did not
leave in the glafs a greater quantity of air comprelled together.
To make trial of this, I took feveral fmall glalles, into one of
which I put a large grain of Gunpowder, into another two, and
into another three of fuch grains, and, having perfedlly clofed all
the glafles, I fet fire to the Gunpowder in each of them, and left
the glalles at reft, until I judged that all the faltpetre particles
were fubfided, then opening the glalles, the air rulhed out with
violence.
I afterwards repeated this experiment with feveral other glalles,
leaving fome of them four, others five days untouched, and, upon
opening them, the air rufhed out with as much violence as in the
former experiment.
Us
( 156 )
^roreover, I took feveral other glafTes, and inclofed in each of
them three {grains of Gunpowder, which (the glafles being fnft care-
fully clofed) I fet on fire ; but in this experiment fonic of the
glalfes flew in pieces, though they were all of the fame lize, and
the quantity of Gunpowder the fame in each. The caufe of this I
took to be, that in the broken gkifles the grains of Gunpowder
might be fired altogether, or blown up more haftily than in the
others. The gkilles which remained uninjured, after tlie fpace of
twenty-four hours had elapfed, I opened in fuch a manner that the
air within them (which in thefe glaifes was more comprefled than
the common air we breathe, and more than the glalfcs themfelves
originally contained) might empty itfelf into a glafs globe filled
with water, having a fmall neck, and placed not upright, but
floping, in order that I might obferve accurately the quantity of air
which was forced out of the glafs wherein the Gunpowder had been
fired into the glafs globe filled with water ; for fo much air as was
forced into the slohe, fo much M^ater mufl: be driven out of it.
To afcertain this, I took feveral glafles, and after having fired
the Gunpowder in them, as before related, I weighed them, though
to avoid prolixity, I will here only relate the computations I made
with one of them. This glafs weighed feventy-feven grains, and
w'hen the comprefled air it contained had been made to pafs into the
before mentioned glafs globe, I filled the other glafs with water^
and weighing it, 1 found that the water contained in the cavity of
the glafs weighed fixty-three grains : with this water I filled up the
cavity in the glafs globe, which had been made in it, by introducing
the air generated by the explofion of the Gunpowder, and I fomid
that fifty-five grains of water had been driven out of the glafs globe,
for I had only eight grains of water remaining after filling up the
cavity or fpace ; confequently, the firing three grains of gunpowder
in the glafs, produced fuch a compreflion of air within it, that when
the glafs was opened, nearly feven-eighth parts of the air it tlien
contained ruflied out ; fo that the air in the glafs, which before
( 157 )
firing the Gunpowder in it was of the fame denfity with common
air, did, upon the tiring, become fo condenfed or compreHed as to
require, for attaining the natural Hate or Hberty, an extenfion of
fpace in the fame proportion.
With thefe obfervations I was not yet contented, and, among
other experiments, I took a glafs, into which I put a common fized
grain of Gunpowder, leaving at the extremity oftheglals an open-
ing the lize of a common pin ; this opening, which was at a thin
and pointed end of the glafs, I immerfed in the before mentioned
glafs globe filled with water, and upon firing this fingle grain of
Gunpowder in the glafs, fo great a quantity of air was driven into
the glafs globe, that to replace the water which was thereby ex-
pelled, I had need of one hundred and fixty grains of water, over
and above the water which had found its Way out of the globe into
the glafs vefiel wherein the Gunpowder was fired. This laft men-
tioned glafs vefiel (which with one more were the only two of fe-
veral ufed by me, had remained entire ; for many of the glalies
upon the rufhing in of the water, buril in pieces), I weighed be-
fore I fired the grain of Gunpowder, in order, after the firing, to
know the fize of the cavity it contained, and found that the water
in it weighed one hundred and fifty grains..
And now, to make a calculation with as much accuracy as poffible,
we muft lay out of the cafe, the fize of the cavity of the glafs
wherein the Gunpowder was fired, and fay only this, a common
fized grain of Gunpowder, in its explofion, forces fo much air into a
glafs globe, as fills a fpace equal to that occupied, by one hundred
and fixty grains in weight of water ; and to make a comparifon
(though it will be a very uncertain one) between the fize of a grain
of Gunpowder and the quantity of air it produces on being fired,
we will fay, that water and Gunpowder are of equal weight, though
this i« not fo in fadl, for Gunpowder finks in water, and therefore
is heavier. Now let thirteen grains of Gunpowder be confidered
to make the weight of a grain, thefe thirteen grains of Gunpowder
( 153 )
multiplied by l6o, the produd is 2080, and fo many times more
fpace does a grain of Gunpowder occupy when fixed, than what it
did before,
Tliis is then the magnitude or quantity in fpace of the expanfion
or explofion of Gunpowder, computed by me with all the accuracy
I was able, though by no means to be deemed perfecit, becaufe one
grain of Gunpowder will explode much more completely than ano-
ther, by reafon that the mixture of faltpctre, fulphur, and charcoal,
is not in their proportions alike in all, as a proof of which, I have
oblerved in firing a grain of Gunpowder, that part of it hiis been
confumed before the reft blew up.
But one circumftance in thele my obfervations appeared moft
worthy -of note, namely, that with the fame velocity as the air
ruflied out of the glafs wherein the grain of Gunpowder was fired
into the glafs globe, with equal velocity was the water forced out
of the glafs globe, through the narrow opening of the glafs where
the Gunpowder had been fired, infomuch as almoft haU' to fill that
glafs with water ; the caufe of which, I conceived, could be no
other than this ; the fire produced by the kindling of the Gun-
powder inclofed within the glafs, requires great extenfion, whereby
the air in the glafs muft in part be driven out, and whereas with
the fame rapidity as the fire was kindled, it will efcape through the
pores of the glafs into the air, fo upon the fire's quitting the cavity
of the glafs, fome other fubftance nmft follow in its place to occupy
the vacuum, whereupon this vacancy in the glafs muft be filled with
water, becaufe the opening in the glafs is immerged under thq
water.
From this regurgitation or ruftiing of the \a ater into the glafs,
when the Gunpowder was fired, after the fire had efcaped from
thence, I was led to refleA on the firing of Gunpowder in a Can-
non or great Gun, and I concluded that a ball fired from an over-
long great Gun would not have fo much force, nor be driven to fo
great a diftance as if the Gun was of a more moderate length, for
( 159 )
1 argued thus with mylelf ; in a Gun eighteen feet long, half as
much time again is required for the Gunpowder to drive the ball to
the muzzle of the piece, than in a Gun which is twelve feet long ;
in which length of time, much of the Gunpowder in the long Gun
is conl'umed, before the ball gets into the open air ; this confumed
Gunpowder is not only wafted, but no fooner is the Gunpowder ex-
ploded, than immediately nearly one-fourth part of the expanfion
efcapes out of the Gun, which fpace muft be filled up by fome
other fubftance, and this is fnpplied from that part of the Gunpow-
der which firft takes fire, and thus the force of the powder is dimi-
nifhed before the ball has quitted the Gun, in like manner as I have
before faid, refpecling the firing of Gunpowder in a glafs, namely,
that fo foon as it is fired and the flame is fpent, the air within the
glafs is rendered fo thin and fubtile, that about a fourth part of the
expanfion produced by the firing of the Gunpowder muft be replaced
in order to fill the glafs again.
In converfation with a certain gentleman of high authority
in military matters, who came to vifit me in company with fome
foreigners of rank, I mentioned my opinion of the inutility of too
long great Guns, (for our difcourfe turned upon that fubje6l), and
he informed me, from his own experience, that upon firing two
guns, one of eighteen feet long, and the other of fourteen feet long,
in order to prove their greateft power, he had feen the gun of four-
teen feet long, carry its ball much farther than the other, which
was eighteen feet long, and hereby I was confirmed in my before
mentioned opinion
It was formerly my firm belief, that there could be no other rea-
fon of the great explofion produced by the firing of Gunpowder,
than firft, from the faltpetre particles being put into a violent agita-
tion and divided into fmaller parts; and fecondly, from the fire,
and that when thofe particles fubfided to a ftate of reft and the fire
efcaped, the remaining fubftances left no greater fpace than they
had occupied before the faltpetre was by the lire divided into many
( lOd )
parts ; but now we fee the contrary to be the fad:, for the particles
of air in a clofed giafs, wherein Gunpowder is fired, are fo com-
prefled together, that feven parts out of eight will efcape out of the
glafs upon its being opened.
I have endeavoured to fatisfy myfelf upon this fubjc(5t, by faying
that the particles of air in their natural Itate in the glafs, before
the firing of the Gunpowder, were, upon fuch firing, divided into
llill finaller particles, and that thole fmaller particles being of a glo-
bular figure, mull: (lb long as they remain dillind: and not forced
one into another) touch each other on their fuperficies, and leave
between them in the remaining fpaces, fome more thin and fubtile
fubllance ; whence it mull follow, that the particles of air within
the glafs, will require a greater fpace than they occupied before ;
but on the other hand, I confidered, that though every particle of
air which was in the glafs before the firing of the Gunpowder
might, upon the firing it, be divided into a thoufand fmaller parts,
this would not produce fo great an expanfion as w^e experience ;
for, let a fack of wheat be ground into fine flour, every grain will
be divided into a thoufand parts at leaft, and though the wheat is
divided into many fmall particles, it will not occupy feven or eight
times greater fpace than it did before the grinding. In fliort, with
all my obfervations refpefting the great expanfion or explofion of
Gunpowder when it is fired, I have not been able to explain the
matter to my own fatisfaclion.*
* Mr. Leeuwenhock,. in this Eflay, attributes the force of Gunpowder, when exploded, to
fome alteration produced by it in the circumambient air, rather than (o the produrtion or
generation of air from the G unjjowder itfell' ; and though in fjmo few places he exprcfles hlm-
felfin a manner, intimating, that air is generated by Gunpowder when fired, he does not
feem to have been fully informed of the do(5lriiie now tftablifliod, namely, that Gunpowder,
or rather its principal romponent, Saltpelrc, contains in it a great quantity of air cond-.'nfod
as much as pofTiblc, which, when fct at libcrly, upon the firing the Gunpowder, doL'.«, by its
elafticity or expanfive power, produce the violent and fiirprifing efl'ffls we obfervc. JVlr,
Leeuwenhock's experiments do, however, confirm that dodtriue, and they arc themfelvtsilluf>r
trated by it.
( 101 )
But when, from the preceding obfervations, we refledl on the
time that Gunpowder, when fired, requires to drive the ball out of
a Gun, and how much of the charge of powder is confumed in that
time ; which confumed Gunpowder is injurious to the effetk of the
iiriiig, and alfo when we conlider how much of the charge may be
driven out of the Gun before it takes fire, the conclufion is, that
it is worthy of confideration to devife ways and means whereby the
whole charge of Powder in a Gun may, if poffible, be let on fire
all at once; and if this be accompliflicd, lb much powder will not
be required for a charge as is now in ufe.
I will now explain the manner in which I make the foregoing ex-
periments on the exploilon of Gunpowder : I take a glafs tube of
the fliape and fize reprefented in Plate XV. Jig. 2(5, L M, at one
end of which I blow the glafs globe H 1 R M, then, after dropping
into it a grain of Gunpowder, I give the glafs the fliape repre-
fented at fig. 27, PO N Q, R, whereby the grain of powder fixes
itfelf in the tube at the place marked N. I then take a fmall pipe,
called by filverfmiths a blow-pipe, which they ufe to folder their
work, and, firll putting on my fpedlacles to defend my fight, I
bring the tube near my eye to fee the effedl of the firing; then
direcling the flame of a candle or lamp, by means of the blowpipe,
to the place where the grain of powder is lodged, it immediately
takes fire, producing the inconceivable number of particles in
violent agitation, refembling fmoke, as I have before defcribed ;
befides the multitudes of particles adhering to the glafs, and
indeed, the number of particles into which a grain of Gunpow-
der is divided, cannot be conceived, but by making the expe-
riment.
I then blow a glafs of the fliape reprefented at fig. 28, S T V W,
taking care that it be fomewhat thicker at the part T, and filling
it with water, I hold it in the oblique pofition reprefented in the
figure.
Vol. II. X
( 162 )
After this, I infcrt the point of the tube reprefented at fg. 27^
wherein the Gunpowder was fired into the aperture of the glafs,
fig. 23, at W, fo that the bent part of the t\ibe R, may prefs the
bottom of the glafs at T, and continue the preflure until the tube
breaks about Q, whereupon the compreffed air in tlie cavity of the
glafs, jig. 27, ruflies violently into the glafs, fg. 28 ; but as it can-
not efcape through the aperture W, it places itfelf about V, by
which means the fame fpace of water is expelled at W, as of air
is forced from the glafs, fg. 27, into the glafs, fg. 28, and u]M)n
weighing this lail mentioned glafs, when filled with water, and
again when part of the water, as before mentioned, has been driven
o\it of it, I can make an cxaifl computation of the quantity of com-
prefied air driven out of the glafs, fg. 27.
Again, I take another glafs of the Ihape reprefented ntfg. 27,.
withthis difference only, that the tube at Q. is flraight, and the
aperture left unclofed, and then infert this into the glals, fg. '28,
fo as not quite to touch the bottom ; then, upon liring tlie grain of
Gunpowder, the condenfed air rufhes with great force into the
glafs 28 ; after which firing, and the heat of the flame elcaping out
of the glafs 27, inflantly, as I may fay, the water makes its -way
through the orifice Q, into the glafs 27, in greater quantity than
one could imagine.
In thefe experiments, by the firing of the Gunpowder and the
rufliing in of the water, the glaties are often broken ; therefore, in
making thefe obfervations, it will be neceflary to repeat the experi-
ments many times.
-*-
Of the louse.
1 HIS animal, which is fo troublefome to many, efpecially the
poor, who have not the means of frequently changing their linen
and other apparel, is by fome writers fuppofed to be produced
from dirt, fweat, or excrements : but to convince fuch perfons of
their miftake herein, I will give the defcription of feveral parts of
this creature, as examined by me, the perfeft and wonderful for-
mation of which, will clearly prove that thefe animals cannot be
produced othervvife than by the ordinary courfe of generation.
Plate XVI. fig. 1 , A B C D E F G, is the head of the Loufe, in
which may not only be {eei\ two very black eyes, but alfo two
pcrfedtly made horns with joints, befprinkled with hairs in many
places, as fhewn at C D and G F. The letters HIKE indicate
only the outline of a part of the Loufe's bodj-.
When I was preparing this object for the limner, I cut off the
head and brealt from the lower part of the body, and placed this
fmall part only before the microfcope ; for when I placed the ani-
mal befoi'e it entire, it was in fuch continual motion, bending its
body backwards and forwards, that it was impoflible to obtain a
diftinft view of it, fo as to make a drawing ; and this piece of the
body remaining fixed before the microfcope, the horns and feet con-
tinued in motion for an hour.
In the contemplation of feveral lice v/hen placed before the mi-
crofcope (and I had plenty of them brought to me for my money),
I received great pleafure in contemplating the motion of the inter-
nal parts in the head and feet, and even in the oefophagus or gul-
let, which in this creature lies partly in the head, and through
which the blood it liicks may be ken running very fwiftly : this
X2
( 1<54 )
motion in the gullet was feen in a clear liquor pafling upwards and
downwards alternately.
J
At E is a protuberance fomewhat like a nipple, which, when the
Loufe is preparing to take its food, itprojeds further, and from the
extremity of it thrufts out its * piercer, in order to fuck the blood.
This piercer, or rather the piercer with its flieath (for there are
two of them, one inclofed in the other), I have often taken out of
the Loufe's head, but it was not till after repeated trials, by reafon
of their exceflive flendernefs, that I could place them before the
microfcope, lb as to give a drawing of them both.
Fig. 2, L O P, is part of the Loufe's head ; at O is fliewn the
protuberance, which I have likened to a nipple, as it appears when
the piercers are protruded out of it : O jNI is the larger piercer, or,
more properly fpeaking, the flieath which contains the piercer
MN, both of which are drawn into the head when not in ufe. At
N, the extremity of this piercer appears a little fpht or divided.
Fig. 3, K L, is this llieath taken out of the head, and L M is the
exceflively flender piercer it contains, protruding beyond the extre-
mity of the flieath.
When the Loufe is about to feek its food from the human body,
it extends the nipple or fnout I have defcribed, from its head, and
from it protrudes the fheath of the piercer ; and lallly, the piercer
itfelf, which being introduced betv%'een thofe fmall fcales with
which the furface of the Ikin is covered, it pierces the blood-vel-
fels lying underneath and then fucks the blood, which is its nou-
rifliment ; and in doing this, it places itfelf upon its head, the more
readily to introduce the piercer into the body. The blood which the
animal fucks, may be feen pafling with a very fwift motion into its
body, and it is a curious fpeelacle to behold the rapid motion with
* The Dtifch word is Angela wliich the Latin verfion renders ylculeuf, both words lignif)ing
a fting: but the Tranflaior has adopted the word piercer, as more applicable to the <\tc
which this part of the animal is defined for : bcfides, we fliall lee prefcnfly, that the ftif!;;
•f the Loufe, properly fo calledj is placed iu a difl'trcut p.irt ol its body.
( 165 )
which the human blood, when received into the Loufe, is incef-
fantly driven to and fro both in the ftomach and inteftlnes, to pre-
vent its coagulating", which would be fatal to the animal.
In my experiments and obfervations on this creature, although
I had, at feveral times, had a number of them on my hand drawing
the blood, yet I very rarely felt any pain from their punctures,
which is not to be wondered at when we conlider the exceffive
llendernefs of the piercer I have been defcribing ; for, upon comr
paring this with a hair taken from the back of my hand, I judged,
from the moft accurate computation I could form by the microf-
cope, that the hair was feven hundred times the lize of this incre-
dibly flender piercer, which, confequently, by its punctures, mull ex-
cite little or no pain, unlefs it happens to touch a nerve. Hence I
have been induced to think, that the pain or uneafinefs thofe per-
fons fuffer who are infelied by thefe creatures, is not fo much pro-
duced from the piercer, as from a real fling which the male Loufe
cai'ries in the hind part of its body.
Fig. 4, BCD, reprefents part of this rting, fo far as it is pro-
truded out of the animal's body, and thus far it is of a hard fub'
Itance and a yellowifh colour like the claw s : in it may be feen a
kind of groove or cavity, which palTes through the whole fting, and
feems as if it were defigned to convey fonie liquor to the extremity
when the animal makes ufe of it, though I never did adlually ob-
ferve any fuch liquor. In this figure the fling is drawn with the
cavity fronting the eye, in which pofition it appears quite llraight.
Fig. 5, E F G, is the fame part of the lling viewed fideways, in
which pofition it appears to be of a curved fhape, and thus far it
was bare of any mufcular parts : the lower part G H I E, in its na-
tural Hate, is covered with mufcular and flelhy parts, which, being
cleared away, there only remains to be leen m the figure, the hard
or horny part of the lling, which gives it llrength and firmnefs.
This lling is tlie Loufe' s weapon of offence, and which it ufes
when preffed by the clothes or otherwife dillurbed ; for I have ob-
( 160 )
len-ed that, when roughly handled, they protrude their lling as
prepaiiri^ tO liriKC ; bui as to the reafon why the males alone are
provided with it, and not the females, I have formed fome conjec-
tures, but not fo as to fatisfy myfelf in that refped.
The feet and cla«'S of this animal difplay the pcrfedl contrivance
manifell: in the formation of fo fmall a creature. Fig. 6. A B C D E F,
is one of the fix feet of the Loufe ; BCD, is the largcfl: claw, one
of Mhich the Loufe has on every foot, and, when the animal is on
that part of the body where there are no hairs, it lays hold of the
ikin with this claw, in order the more forcibly to introduce the
piercer which it carries in its head into the body, in order to fuck
the blood ; but when moving from place to place, or not employed
in fucking the blood, it does not cling to the body, but to the
Ihirt or other garment (on which alfo it lays its eggs), becaufe it
can eafily fix its claws into the filaments of the linen or woollen.
To lay hold of a hair it grafps it with this claw and the prominent
part of the foot, which is Ihewn at D, and which is alfo provided
with a very fmall nail or claw, and more particularly the part E
which I call the Loufe's thumb, and which is alfo furniihed with a
fmall nail. For in like manner as we, in holding any thing in
our hands, ufe the thumb, fo does the Loufe in grafping a hair
make ufe of what I call its thumb. A F G, is that part of the
Loufe's leg which joins the body.
I could have given a drawing of the Loufe's claw magnified to a
greater fize than the whole foot is here reprefcnted, but I do not make
ufe of fuch very deep magnifiers, unlefs neceffity requires it ; for I
think that an object is fufficiently magnified when we can fee all the
parts of it difiindly.
Upon exhibiting this creature before the microfcope to a certain
great perfonage, he obfervcd to me, that his foldiers, who were in-
felled with lice, found them more troublefome in rainy than in dry
weather: for which I gave this reafon, that the clothes, when wet-
ted, Ihrink and comprefs the body fo clofely, as to impede the
( ^67 )
Lovife in its motions, and caufe it to ufe the lling which it carries
in its tail, whereas, in dry weather, the clothes hanging ioofe on
the body, tlie Louie has room to infert its piercer and luck its
food, which it cannot do without bending its body and railing its
hind pai'ts.
The Louie is fo prohfic an animal, that it is a common vulgar
faying, that it will be a grandfather in the fpace of twenty-four
hours. This I could never believe to be the fad;, but rather that it
would require nearly a month for the offspring of a Louie to be ca-
pable of producing young of its kind ; and, in order to make proof
of it by experiment, I at fn-ft propofed to hire fome poor child to
wear a clean Hocking for a week, with two or three female lice ia
it, and well tied or fecured at the garter, in order to fee how many
young ones would be produced in that ipace of time ; but 1 after-
wards confidered, that I could make the experiment with much
more certainty in my own peribn, at the expence only of enduring,
in one leg, w^hat moll poor people are obliged to fufFer in their
whole bodies during all their lives.
Hereupon I put on one leg, inllead of the white ujidcr ftocking
I nl\;ally wear, a fine black ftocking, chufmg that colour, becaufe
I confidered that the eggs and the young lice thence proceeding,
would be more ealily dirtinguifhed upon it. Into this ftocking I
put two large female lice, and cutting another black ftocking into
long Hips, I bound it over the firft above the knee, to prevent their
efcaping. After wearing this ftocking fix days, I took it off, ar.d
found one of the Lice in the fame place w^here I had put it, and
that it had laid fifty eggs, and in another part of the ftocking the
other had laid about forty eggs, but the parent I could not find. I
opened the other which had laid the fifty eggs, and found in its
body at leaft fifty more, and who knows how many eggs it had laid
before I put it into the ftocking, and how many more eggs it might
then have in its body which my fight could not reach ?
Having worn the ftocking ten, days longer,' I found in it at leaft
( 1C8 )
twenty-five lice of three different fizes, fome of which I judged
were two days old, others a day old, and the rcll newly come out
of the egg, belides others- ready to come forth, as I found ujion
opening one of the remaining eggs. l]ut I was fo difgulled at the
fight of fo many lice, that I threw the liocking containing them
into the ftreet ; after which I rubbed my leg and foot very hard, in
order to kill any Loufe that might be on it, and repeating the
rubbing four hours afterwards, 1 put on a clean white under
flocking.
I have caufed a drawing to be made of the Loufe's eggs, (com-
monly called nits), as viewed by the microfcope, to fliew from what
part the young Loufe ilfues forth. Fig. 7, IS () P, is the egg, Q R,
is a hair of the wool to which the egg is fixed, by means of fome
gummy fubflance, which the Loufe emits from its body together
with the egg. At N, is fhewn how part of the egg is shaped,
foraewhat like a lid or cover, which in all probability is made very
tender or brittle, that the young Loufe, when. grown to its full fizc
within the egg, may be able to break it open and ililie forth ;
whereas other young animals, who are provided with teeth or pin-
cers, can gnaw or bore holes in the fliell. Fig. 8, S T V, is ano-
ther egg, A\ herein, at T, may be feen that the flieli of thefe very
fmall eggs is provided v/ith a fkin or membrane, the fame as a
hen's or other bird's egg ; and under the lid or cover of this egg,
which the young Loufe breaks open, there is another thin mem-
brane, which is alfb broken by the young Loufe, and is to be feen
atT.
Now fince we fee, by experiment, that a Loufe in the fpace of
fix days can lay fifty eggs, and have as many more remaining in its
body, we may eafily conceive, that a poor perfon who has an hun-
dred female Lice about his body, and has not any change of clothes
or linen, and who, moreover, through floth is carelefs of deflroying
thofe he has about him, may in a few months (if I may ufe the
expreffion) be devoured by thefe vermin.
( m )
To give a clearer conception of the great increafe of thefe animals,
let us fuppofe a perfon to have about his body two male Lice, and
as many females, and that the females in twelve days time lay two
hundred eggs, and that, fix days afterwards, out of thofe eggs are
produced an hundred males and as many females, and that this
young brood in eighteen days time are grown to a fize to propa-
gate their kind, and that each of thofe young females in the fpace
of twelve days more lays an hundred eggs, from which, in fix days
time, other young lice are produced; upon this fuppofition, the
number of lice fpringing from two females, will amount to ten
thoufand. Thus it appears that two females may, in eight weeks
time, be grandmothers, and fee ten thoufand lice of their own off-
fpring, which, unlefs reduced to actual demonllration, would feem
incredible ; and who can tell, whether in the heat of fummer thefe
creatures may not breed in half the time I have mentioned ?
I will here put an end to this loufy difcourfe, which has gone to *
three times the length I intended ; but my defign in it was, to fa-
tisfy myfelf, and to convince others, that fome days are required for
the egg laid by a Loufe to produce a young one, befides the time
required for eggs to be again laid by fuch young one, and alfo to
afcertain in what numbers thefe creatures do multiply.
♦ In the original, the author is much more prolix aud circumflantial than here fet down ;
but theTraiiQator has thought it fufficicnt, on fuch a fubjed, to give the fubflaacc and gc
Reral rcfult of bis obfcrvatioas.
Vol. II.
Of the mite.
1 HE Mite is the fmalleft animal that I have ever obferved about
our houfos, but in every kind of dried provifion, fuch as ham,
bacon, and dried fifli, they are almoft always to be found.
In reflecting upon this animal, I was defirous to know the na-
ture of their propagation, and how long time their eggs would
take from their being firll laid to their being hatched, and alfo in
what Ipace of time a young Mite will come to its full growth.
In catching thefe creatures, I found they were endued with a
very quick fight, for after I had once touched them with the inftru-
ment with which I caught them, they afterwards avoided it in a
manner which furprifed me.
I had often feen the eggs of Mites in cheefe and other fubftances,
and I now proceeded, by the help of a magnifier, to open fome of
the largefl: mites, which I judged to be females, and viewing them
by a microfcope of ftill deeper magnifying power, I faw at three
feveral times, not only the eggs, but alfo through the fhells of
them I perceived their infide to be compofed of greater and fmaller
globules, exadly fimilar to thofe in the yolks of hen's and other
birds' eggs, only with this diiFerence, that the globules in the yolk
of a hen's egg are each of them larger than the entire egg of a
Mite.
I took a glafs tube, into which I put a piece of bifcuit and five
or fix Mites, and then, by the help of fire, I clofed the orifice of
the tube, fo that no egg laid by the Mites could drop out ; the firfl
day of their confinement I found one egg, the next four, and the
third fix eggs, and one of the Mites dead : the fourth day I
counted as many as twenty eggs, and afterwards fiill more, but
( 171 )
the number I did not particularly reckon ; and as it was in the
middle of 0<ftober, and the weather growing cold, on the fourth
day after the firft egg was laid, I put the tube into a leather cafe,
and carried it in my pocket, to fee what time the eggs would re-
quire to produce young Mites. On the eighth day I faw a young
Mite, and the following day three fmall Mites creeping about the
glafs, and then I faw only oTxe of the Mites I had put into the
glafs remaining alive; and, upon minutely examining thole that were
dead, I judged that they had been almoft wholly devoured by the
furvivors. The next day I faw five or fix fmall Mites, but I was
furprifed to fee thofe young Mites had only fix feet, whereas thofe
which were grown larger had eight.
By the microfcope I every day examined the eggs, and when they
were about four days old, I could diftinguifh the fruitful from the
barren ones ; thofe which I deemed fruitful were of a dark colour
throughout, whereas the barren ones were one half dark and half
tranfparent, which tranfparency was occafioned by the globules
which compofed the egg having funk to the bottom. Afterwards
I faw that from all thofe eggs which had remained dark through-
out, the young Mites had crept out, leaving nothing but the fhell
behind them ; whereas thofe eggs which were in part tranfparent,
remained entire.
Not fatisfied with thefe obfervations, I took feveral glafs tubes, into
each of which I put fome fmall pieces of dried fifli, and thefe tubes
being clofed at one extremity, I placed the open ends near a bag of
meal, in which I was certain there were many Mites, in order that
the Mites might of themfelves, without being hurt, or being mixed
with any dirt, remove into thefe glafs tubes to the pieces ot fiili,
which accordingly came to pafs ; for, the next morning, I found in
fome of the tubes fifty Mites, as well large as fmall ones, and fome
fo minute, that they feemed to be newly hatched, and had only
fix f et.
In order that thefe Mites might not want air, I clofed the ori-
Y2
( 172 )
fices of the tubes fo as to leave an opening at the end in fome of
them, as far as my eye could judge, about the fiftieth part the
fize of a Mite's egg, and others larger : thefe glafles I then placed
before the microlcope, for thefe creatures, by reafon of their mi-
nutenefs, are almoft invifible, and by my naked eye I could not
perceive they had any life in them.
I have given a drawing of the Mite, as feen through the micro-
fcope, to fhew its Ihape as nearly as the limner could imitate it.
Plate XVI, fg. 9, A B, reprefents the Mite's egg, the fliell of
which is covered with fo many fharp prominent parts, that the
whole appears dotted : thefe eggs may be feen in great numbers,
in the rinds of cheefe, efpecially when the cheefe is old and Mites
are difcovered in it. Fig. 10, C D E F, is a Mite feen through the
microfcope when fixed to the point of a needle. This creature
has eight feet, in each of which the joints are reprefented as accu-
rately as could be done ; moreover each foot is furnillied with two
wonderfully minute crooked claws at its extremity, m ith which the
animal can readily grafp any thing, and fupport its own body ; and
I have feen a Mite, when fixed to the point of a pin, lay hold
with its claws on the hair of another Mite and fufpend it in the
air, and I wondered that a fingle hair of a Mite Ihould be fo firong
as to hold the animal's body fufpended by it. At D is fliewn the
head of the Mite, the tore part of which is fo very fliarp, though
with an opening on it, (from which opening I have feen fome-
thing like a tongue put forth),, that the mouth might be fitted to
bite afunder the fibres of the flcfli on which it feeds, as I have
feen in the feet of a loufe gnawed by a mite, leaving oblong
fcratches. On each fide of the head was a crooked hair, beginning
at the thicker part of the head, and ending near the extremity, as
if it were alfo fixed there, which at firll I thought it was, but hav-
ing often feen that when a Mite touched thefe hairs, while clean-
ing its head, in the manner that cats and other animals do, the
hairs when moved out of their place recovered themfelves with a
( ^73 )
kind of fprlng, whereupon I thought that thefe hairs might be de-
figned to protect the eyes.
The Mite here pictured was not one of thofe taken out of the
meal or cheefe, but a piece of fmoke-dried meat, which abounded
with them ; thefe Mites were of the fame fliape with others, but
fomewhat larger, which I prefumed might be owing to the abun-
dance of moid nourilhment they got from the meat, which thole
in the meal had not ; and when I put feveral of thofe Mites from
the dried meat into a glafs, they could not move about readily, but
remained almotl fixed in the place, or moved very llowly, becaufe
they could not fix their claws in the glafs, and the hairs on their
bodies, by the fatty particles they had contra6led, lluck to the
glafs.
I have obferved thefe animals remain many weeks without food,
and alfo to endure the cold, and even lay eggs in cold weather,
which in about a month's time produced young Mites.
And now, if we contemplate the wonderful regularity, as well
in the formation, as in the propagation of this animal (the minutefl
as I have before obferved, that is found about our lioufes, and by
reafon of its minutenefs, unknown to or unobferved by many), mufl
not the moft judicious philofophers agree with me in opinion, that
as it is impolTible for an elephant to be brought forth from duft or
dirt, it is equally impoffible for a Mite to be bred out of meal or
any corrupted fubflance, or in any other manner than the regular
way of generation I have defcribed.
*
Of a Maggot, which feeds on the grafs in meadows, and a Fly hi^ed
from it in the Spring : tvith fome remarks of the author on the
Grafshopper and the Lociifl.
In the month of May I was fliewn, by a countryman, a meadow
which, though good land, was very tliinly covered with grafs, and
the reafon he gave for it was, th^it a certain fpecies of black, thick,
and fliort maggots devoured the roots of the grafs ; and he added,
that the grafs would not grow, until there fliould be fome hot wea-
ther, by which thefe maggots (called in our language den HemelfJ
would be killed. I alked him whether he ever obferved that thefe
Maggots changed into fmall Grafshoppers, or into any other flying
animal, but to this I received no other anfvver than, that the Maggots
would foon difappear if there were but a few hot days, and then the
grafs would grow plentifully: and he farther laid, that tlie lower
marfliy lands, in which grafshoppers are feldom fcen, were moll
infested with thefe creatures. And the country people fay, that
after a few hot days they often fee thefe maggots l}ing dead in the
fields.
This information, which I received from different countrymen,
was not fatisfa<ftory to me, for I judged that if thefe Maggots were
accurately obferved we fhould fee a different appearance, namely,
that they would be found to change into flying animals, and the ra-
ther, becaufe thefe Maggots, are not found in numbers together, but
difperfed about fingly.
About the beginning of May I went to a meadow which was but
thinly covered with grafs, and took with me a couatrvman, an in-
telligent perfon, who lived by keeping oxen and horfes at pallure :
( J75 )
this man fearched for the Maggots with me ; I put fome of them in-
to a box, but in a fliort time they partly flirivelled up and died ;
others of them I put on a turf of grafs, which I placed in an earth-
en vefl'el, and watered it every day ; this veflel I fet in my ftudy, that
I might remember to view it frequently, and when the grafs began to
wither, I replaced it with a frelh turf : in doing which I faw more
of the Maggots lie Hill on the earth, I thereupon took the turf which
began to wither, and, taking from it the Maggots, I placed them on
the frelh turf : and this I continued to do till the end of July, in all
which time I perceived no alteration in the Maggots. In the mean
time I chanced to be in the company of fome gentlemen of refped-
ability, with whom converfmg on this fubjed, they told me that
thefe Maggots would be changed into flying animals, called, in our
language, Speketers. But, though I was well allured, in my own
mind, that fome fuch change would take place in thefe creatures, I
determined to fupply them with frefli earth, until I fliould fee their
transformation.
In the beginning of Augiift the turf again began to dry, and, con.
lidering that fo long as three months time had now elapfed, I exa-
mined the turf, and took the Maggots out of the earth, when I faw
one of them, which was whiter than the others, to be fomewhat con-
tracted, whence I judged that its transformation was at hand; where-
upon I placed it and two others of the Maggots in a box, and the
next day 1 faw one of them was changed into an aurelia or cry-
falis, having put off its fkin, which lay belide it. I fought for ano-
ther of the Maggots which was changed into a cryfalis, but which
I had not fliut up in a box, and, not finding it, I concluded it had
changed into a flying animal and efcaped. The other Maggots were
in a Ihort time contraded, but did not undergo any further change.
Plate XVI. Jig. 11, ABC, reprefents the Maggot called den He-
melt, in which, from the month of May to Auguft, I perceived no
alteration in (hape. Fig. 12, D E F, reprefents the Maggot changed
into an aurelia or cryfahs, which at firft was in frequent motion,
( 170 )
and did not lie Itill till that part which was its back was placed iip-
permort. Fig. 13, G H, is the ikin put off by the Maggot.
Two days after 1 had perceived the change 1 have been defcribing
in the Maggots, I went to the meadow where I had found them,
where I faw a great number of creatures flying about, which our
children call Spcketers, and others Maimers ;* these are reprefented
at Jig. 14, I K L M. Some of thefe flying animals I brought home
in a box, to fee whether they contained any eggs, but I could find
none, and the animals feemed to me to be all of the fame fliape. I
again fearched in the meadow, to fee whether I could find any dif-
ference between the males and females, but without fuccefs.
In the mean time I faw, flying in my garden, a fingle animal of
the fame fliape with the before mentioned ones, with this difference
only, that it was fomething larger and its tail tern^inated in a point,
whereas thofe of the others were blunted at the end. Tliis animal
I opened, and took out of its body a great nmnber of oblong black
eggs, infomuch that, on counting thofe taken out of this one animal,
they exceeded two hundred. Others of thefe animals I found in the
town, all containing eggs, but I did not find one in the town of the
fame fliape as thofe which I had taken in the field, which made me
doubt whether both were of the fame fpecies.
In the beginning of September, on going again to the meadow,
I did not at firft fee any animal, except thofe I firll defcribed, and
which are reprefented at fg 14, but after I had flood there a while
I faw one of the fame fort with thofe from which I had taken the
eggs. This creature, fettling on the ground at a fmall diflance from
me, extended the hind part of its body downwards through the
grafs, and remained in that pofture a fliort time : this it did three or
four times while I was looking at it, forcing its way between the
blades of grafs fo clofely, that when I wanted to take it, I could not
* From the figure given of thefe animals, it ihoiild fcem that they are what are called, by
children in England, father long-legs, and in Summer CTenings arc often fecn in our boufct.
( ^n )
eafily feparate it from them, and I faw this performed by three or
four others of the animals while I rtayed in the meadow.
From thefe obiei'vations I concluded that both the animals I have
mentioned were of the fame fpecies, btit thofe which I had taken firft
were all males, and thofe from which I extracted the eggs were fe-
males, the females being of a larger fize, in order to contain the eggs
they were to lay ; and that the Iharp points of their tails were of a
hard bony nature, and defigned to penetrate into the moift earth and
there depofit their eggs, which otherwife, in my opinion, would be
barren.
On my return home, when I examined the animals I had taken,
I found fix of them to be females and ten or twelve males, fome of
them were coupled together, which proved them both to be of the
fame fpecies ; and it feemed probable to me that the llrong winds,
which had prevailed for fome days paft, had brought fome of the
females, which had not llrength to refill them, into the town.
The next day moft of thefe animals were dead, and I concluded
that their deaths had been caufed by my handling them too roughly,
fb as to break fome of the many veflels in their bodies.
Fig. 15, N O P Q, reprefents the female of this animal, and at N
may be feen how fliarp pointed is the hind part of their bodies, to
enable them to depofit their eggs in the earth ; this part is divided
into four dittinct parts, as joints, both above and below, which fe-
parate and open themfelves.
The eggs of thefe creatures, of which I have faid that I took more
than two hundred out of one parent, are very black, and of fo fmooth
a furface that they fliine like black glafs ; they are about twice as
long as broad. The thell of them, in proportion to their fize, is
very hard and thick, and yet I always found that thefe eggs, whe-
ther laid by the animal, when confined, or taken out of their bodies
by me, did, in a fliort time, futFer fuch an evaporation of their
moifl;ure, that the fiiells were comprefled inwards : which fudden
.evaporation I have not obferved in the eggs of much fjnaller infedls.
Vol, II. Z
( ^78 )
From hence I concluded that the conllitution of thefe creatures whs
fo ordained by Nature, that this Maggot, in the middle of Summer,
w hen the atmofphere is very hot and the earth dry, does not undergo
any change nor lay its eggs ; for if thofe eggs were laid in hot and
dry earth, they would be foon dried up and become barren, whereby
the fpecies would be expofed to perifli. But, as thefe animals lay
their eggs in the month of September, when our lands are all wetted
with rains, the eggs, being laid in moill earthy do not dry up, but
remain fruitful.
Having obferved that the animals I had put into a box in the
beginning of September, had laid fome eggs in it ; I did, in order
to prcferve them, put them into a box almoll filled with moift
fand, and covered them with more of the lame, and carried them
in my pocket for fourteen days, to give them warmth, and fee whe-
ther any Maggots would be produced from them, and I daily opened
fome of thefe eggs, but coidd not fee any appearance of young
within them.
I often opened the bodies of thefe animals, both the males and
females, and was furprifed at the wonderful number of veffels and
organs they contained, infomuch that I muft fay, that the fpedacle
would excite more admiration than to view the inteftines of larger
animals with the naked eye ; and this was particularly the cafe in
the hind parts of the bodies of both males and females, which,
viewed through the microfcope, exhibited fuch a fpe6lacle, that I
never faw the hind part of the body of any animal, wherein were
fo many organs with their joints, the ufe of which, though doubt-
lefs efl'ential to the animal, are to us unknown.
Since we fee now, as I have fiiid, that the female of this animal
can lay moi'C than two hundred eggs, it plainly appears, that if all
the animals of this fpecies which are bred in one fiimmer were to
increafe in the lame degree, within two or three years they would
fo multiply, as to devour all the roots of our grafs ; but by drought*
in the earth, great rains and ftorms, and fevere frofts, many of
( 170 )
them are deflroycd, and we are not infclted ^^itl^ them equally
everv year.
From the generation of thefe creatures, we may make a tranfi-
tion to that of Loculls, which are fovmd in Eallern countries, and
devour the fruits of the earth, and when they have no other
food, devour one another. VVc do not often fee Grafshoppers,
(which are fimilar to Locufts) near this town, but I had at one
time a parcel of large ones brought to me, which I put into a
glafs and fed with vine twigs, but obferving that the large ones
devoured the fmaller, I fepan^ted them, and found that the females
laid above eighty eggs. Now, if we fuppofe, that Locufts do the
fame in extenfive countries where the Maggots are not expofed to
tempefts, hea\7' rains, or frofts, (and I am well allured, that Lo-
cufts are produced from Maggots, from the obfervations I have
made on Grafshoppers in this country, which are of the Ipecies of
Locufts), we may eafily conceive that Locufts in thofe countries
may multiply to that degree, that they may vifit the neighbouring
countries in fwarms. Thefe are merely my fentiments on this fub-
je6l, which, however, I think more confonant to right reafon, than
the notions of thofe who dream that Locufts come out of the
clouds for the punifliment of mankind, as I have often heard in
converfation.
Z 2
On a Maggot ivhich is found in the hlojfoms of fruit trees, particu-
larly apples ; the Fly from whence it is produced particidarly de-
scribed ; tvith the Author s reasoning on the production of minute
"flying animals.
Although it has always been my firm opinion, that no ani-
mal, however minute, is produced any otherwife than by courfe
of generation, neverthelels, I determined to profecute my inquiries
in the examination of thofe minute FHes and other infcAs, which
are found on the leaves of fruit-trees and plants in gardens.
Having heard frequent mention made of a certain black Fly,
which was faid to be very noxious to the bloflbms of fruit trees, I
examined the bloflbms on the fruit trees in my garden, and parti-
cularly the apple-trees, and found that many of the flowers did not
blow out fully, nor were they of a white or pink colour, but ap-
peared fhrivelled and of a kind of rulty red.
Upon opening thefe bloflbms, I found within the leaves of mod
of them a Maggot of a pale yellow colour, and in fome of them a
cryfalis, which I concluded had been changed by tranfmutation,
from one of thofe Maggots ; and as I, at the fame time, ob-
ferved many black Flies on the leaves and flowers of thofe fruit
trees, I concurred in the common opinion refpeding them, and
concluded that thofe Flies had laid an egg on each flower, from
which Maggots had been hatched, and that they, being changed
into cryfales, did at length produce the fame fpecies of black Fly.
At the fame time, I was of opinion, that if thefe Maggots were
not depoflted within the bloflbms before they were full blown, few
of them would be preferved alive, becaufe this Maggot is not in-
clofed in a web or cafe, as we obfen-e in moll other cryfales, and
( 181 )
therefore would be expofed to be devoured by fmail birds, or even
hy common ants ; for I faw, that where an ant could find its way
into the bloflbm, it had eaten up part of the Maggot or cryfalis-
But thefe Maggots when enclofed within the bloflbm, do bite or
gnaw the velTels of its leaves in a manner, that not only the buds
dry, but are dole fhut up, and thus afford a defence to the Mag-
got during its growth, and until it is changed into a flying ani-
malcule.
In thefe my obfervations, many things occurred to me worthy of
note : firll:, that in all the bloflbms I examined, I never found
more than one Maggot in each flower ; fecondly, that from the
fmall nourifliment it there received, it grew apace; and lafl:ly, that
in a few days it became fo perfedt, as to be transformed into a
cryfalis.
Many of thefe bloflbms I pulled from the trees, concluding that:
no flower which contaiiaed a Maggot or a cryfalis, would ever pro-
duce any fruit. Placing fomc of thefe before the mifcrofcope, I
perceived that the crylalis and the young animal it would produce,
bad no affinity with the black Flies I have mentioned ; and to be
more certain of the fact, I put into a glafs tube four of thofe cry-
falcs, which I carried about with me in my pocket, and at the end
©f five days, I perceived one of them had changed its pale yellow
into a red or blackifh colour, and foon afterwards it put ofl' the
Ikin which inclofed it, and ran about the glafs : on the eighth,
day the three other cryfales put off" their Ikins, but fome of them
were of a darker colour than others, having relpedl to the time they
had been in their cryfalis ftate.
I now perceived that, with many others, I was miftaken, in fup-
pofing the blight, or rather the Maggots we perceive in the blof-
foms of fruit trees, to be produced by the black Flies ; for thefe
animalcules, I was now obferving, had, as I before mentioned, no
limilitude to the bodies of the black Flies ; firfl^, becaufe they were
not nearly fo large ; and fecondly, becaufe that which 1 found
( 182 )
within the bloflbms, when changed from a Maggot into a flying
animal, was provided with two Ihells or cafes, folded lengthw fe
over its wings, as we fee infedls of the beetle tribe ; moreover, the
fore part of its head was furnifhed with a long probofcis or trunk, dc-
iigned by Nature, as I fuppofe, for perforating the buds of the blof-
foms before they were blown, and through the hole to introduce
an egg, whereby the egg and the Maggot produced from it, might
be protedled from its enemies, particularly birds and pifmires ; this
probofcis, about the middle of it, was provided with two horns.
I again viiited my garden, where many of the trees were yet in
bloom, but neither on the trees, nor on tlic flowers, could I difco-
ver any of thefe flying infe<fls, which had been brought to their
perfe<9;ion while carried about in my pocket ; though in fome of
the flowers which I opened, I found Maggots, and in others cry-
fales, yet not in one a flying animal ; whence I concluded, that fo
foon as from a cryfalis they arrived at that Hate, they forfook the
blofl'oms and took their flight.
At the times when I took the Maggots I have before mentioned,
out of the flowers, they twifted and bent their bodies many ways ;
but I never law them move progrefllvely ; for when 1 placed them
upon a paper, they could not change their place, but rolled them-
felves up in a kind of ring, for thefe creatures have no feet; there-
fore, each ISIaggot mull be placed in a bloflbm by itfelf, and cannot
injure more than one flower.
One thing fecmed to me very remarkable, namely, that all the
food which this Maggot took from the bloflbm (at leaft, as fiir as I
could perceive), became part of its body, for when I examined the
flowers wherein the cryfalis had lain, I could never difcover any
appearance of excrements, but only the fkin loft behind by the ani-
mal upon its transformation.
In thefe my obfervations I could not but take notice how Nature,
that provident parent, has created this animal fo as not only to derive
its fupport and growth from fo fmall a portion of aliment, and in fo
little time, but alfo by appointing it to be placed within the bloflbms
( 183 )
of fruit trees, and there brought to perfeAion for the confen'ation of
its fpecies, otherwife (as before mentioned) it would be devoured by
pifmires or birds : and it mxilt aUb be obfersed, that thefe creatures
have no ability of fceking their food at a dillancc.
Befides what I have mentioned, I had others of thefe cryfales,
which I kept in my ftudy to vsatch their transformation, placing them
in a glafs, fo as to give them a fupply of air; but I never could per-
ceive the leaft appearance of any evaporation from them, though, as
foon as they were converted into living animals, fo great a quantity of
moifture iflued from their bodies as to hinder their moving, and often
to occafion their fi:icking on their backs to the glafs, which made it
neceflary for me to give them more room : here is to be noted how
wonderfully compact muft be the fkin of the crylalis, fo as to fuffer
no evaporation of its moitiure, left the animal within fhould be injured
by the want of it ; and this is another inftance of the inconceivable
correctnefs of Nature in her works.
Finding myfelf miftaken in opinion, refpeAing^ the black Flies de-
pofiting Maggots in the bloflbms, I determined, if polTible, to exa-
mine the nature of their propagation, and the rather as I alTured my-
felf that they muft be produced by cryfales. I therefore opened fome
of thefe black Flies, and I can fafely fey that, from a rough calcula-
tion, I found in each female three hundred eggs.
Going into my garden in the morning, to take fome of thefe Flies,
that I might confine them till they laid their eggs, and I might dif-
cover what kind of cryfales would be thence produced, I perceived
the Flies fitting on the leaves and flowers as immoveable as if they
were dead, and even, upon a gentle touch of the branches, to fall
to the ground ; whereas all other Flies, in warm weather, are very
nimble. Hereupon it occurred to me that, when the wind blows
from the North, Flies do not rove about in the air, but lit upon the
trees, where we obferve them in greater numbers than when the
air is warm ; and as in cold and cloudy weather they fettle in great
numbers, not in the fummits of trees, but in the lower branches,
( 18-1 )
many people think they are brought to us by the North wind, or
even bred in the clouds : but fuch men I leave in their error.
Thefe black Flics (and clpecially thole which I had fuppoled to be
impregnated) being confined in two glall'cs, laid a great number of
eggs, very long in proportion to their thicknefs ; whence I gathered
that they would be changed into very long and flender Maggots or
Caterpillars. But as all the FUes foon afterwards died, and not one
of the eggs produced u living creature, I confidered that perhaps
thefe Flies might die for want of food, and that the eggs might be
.aid before their time, having often obferved flies and moths when
I happened to handle them fo roughly, that they afterwards died,
immediately after fuch handling, to empty themfelves of all the
eggs they contained.
I did intend here to defift from publiflfmg any thing farther re-
fpe6ling the propagation of thefe infedls, deeming that I had proved
fufliciently, that all living creatures were produced by the ordinary
courfe of generation ; but my friends in different parts of the world,
exhorted me to proceed in my difquifitions on this fubjc<ft, as being
w^hat many learned men defire may be profecuted.
To proceed then in my examination of this fubjeft. In the
month of May, in the following year, the weather being warm,
and my fruit trees in blollbm, I fought for fome of the flying in^
fedls I have mentioned, and prefently faw many of them coupling
together. But though they were nimble in their motions, and well
fitted to fly, and moreover had fix feet, and on each foot two
claws, yet on my fliaking the leaves or branches ever Jo littlQ,
they gathered up their feet and fell to the ground ; feveral of thefe
fmall animals I brought to my ftudy in a glafs, to make my obfer-
vations on them.
1 found the wings of thefe creatures to be about twice the length
of their bodies : but, if we confider that thofe wings are covered
with thoufands of hairs, and obferve, that when the wing is fpread,
not t)ie Jeall fold or joint can bedifcovcred in it, though it Iks 9n
( i85 )
thie body folded together, v,C muft be loft in admiration, and th^
more, when we recoiled the multitude of vcftels and joints, and
alfo mufcles, requifite for the formation and expanlion of fuch a
wing ; and we may well alk, whether any man in his fenfes, who
is not erltirely blinded by prejudice, can contemplate fuch a crea-
ture, by the microfcope, without acknowledging that it could not
polTibly be produced from corruption, Or the putrefied bodies of
other animals, and will he not rather cry out in the words of an
eminent gentleman, who lately came to fee my microfcopical ob-
jedls, " O the depth of the Divine Wifdom, how infcrutable are
" his works ! Can any m.an after this, be found to deny the being
*' of a God ?" or fuch like expreffions.
I caufed a drawing to be made of this infedl, the fame llze as it
appears to the naked eye, which is reprefented in Plate XVI.
.fg. lO, and to avoid giving a drawing of the whole animal when
magnified, I cut off the head, and placed it before a microfcope to
be delineated, in order hereby, to flicw how the careful parent,
Kature, has created this fmall animal, that its fpecies may be pre-
ferved, and the order and perfection with which the world was at
firft created may not be diminifhed.
Fig. 17, A I, reprefents part of the head: BH are the eyes,
which, in like manner as the eyes of Flies, are formed of many opti-
cal organs, and appear with as many protuberances as the fub-
ftancc, called fliagrcen, appears to the naked eye.
C D E F G, is that organ or trunk, with which, as I fuppofe,
the animal perforates the bloflbm, while yet a bud, in order to lay
ian egg in every bud ; to which end, its extremity is provided with
various piercers or teeth, and other w^eapons, which are, in fonie
fort, reprefented in the drawing, but the whole of which, the lim-
ner could not copy, becaufe the animal, while alive, was opening
and fhutting, or extending and contradting, thefe organs, and, when
dead, they were almoft out of fight ; and though I did all in my
Vol. II. A a
( 186 )
power fo io fix them, that they might remain vifible without the
body, I could not fucceed.
This organ C D E F G, is fomewhat larger than it here appears,
becaufe it is bent forward, and, being viewed from behind, the
bend in it could not be deftribed, therefore I gave the hmner ano-
ther microfcope, exhibiting a tide view of the fame, and a Iketch or
outline of its curvature is to be feen at fig. 18, M N O.
D K and E L are the two horns with which this organ or trunlv
is furniflied.
After this, I again looked over eight or ten of my apple trees,
and, in the fpacc of half an hour, I collected thirty of thefe infcds,
which I Ihook from the leaves into a large glafs tube, that they
might not be hurt by my touching them, and I might be able to
obferve how long they could live without food, and alfo, whether
they would lay any eggs. While taking them, I obferycd, that
not only, upon the leall motion, they drew up their feet and con-
tracted their trunks and fo fell down, but that fome of them did
the fame upon being only touched by my hand, or by the glafs.
- But what I moll wondered at was, that two third parts of thefe
infedts which I found on the trees, were coupled together, and I
could not conceive how fvich f^nalj animals could find each other out
in fo large a fpace, and the rather, becaufe in a tree, the circum-
ference of which was more than thirty-fix feet, I only found four
or fix of them, but all in couples.
Obferving that thefe infeds could run along or {land for a long
time on any fide of the glafs, even with their feet upwards, I was
defirous to examine accurately the formation of their fee^, and, in
this little creature, I faw fuch perfeftly formed limbs, enabling it
to adhere to the glafs, and to run along upon its furface, as dif^
tin6lly, as I had ever fcen in other larger flying animals.
Fig. 19, P Q R S T, reprefents almofi a fourth part of one of the
legs, confifl;ing of four dillindl joints : the other part of the leg has
only two joints. At R and S, are two claws or nails, whiph are
( 18-7 )
in Tome fort tranfparent, like a piece of horn or tortoife-lliell, feeii
with the naked eye, and at Q and T, are fhewn the organs, by the
help of %\ hich the animal can run along the fniooth furface of the
glafs, and alfo hang to it a whole night. The formation of thefe
organs is very wonderful, for all thofe parts with which they are
covered, and which one would conclude to be hairs, are fo exacflly
and regularly floped off, and particularly of fuch regular lengths, as
if they had been all clipped with fcilfars, that when the animal
places its foot any where^ they all touch the place at the fame time,
and what is more, all thefe particles, which feem to the eye to be
hairs, have at their extremities a hook, and, at a little diftance
from tlrence, two other hooks ; but by reafon of their extreme mi-
nutenefs, though the limner eonfefled he faw them through the mi-
crofcope> he declared he could not reprefent them in the drawing.
Now if we confider, what I have always experienced, that a
glafs, though wafhed ever fo clean, will have many particles ad-
hering to it, tliough thele are fo fmall, that the claws on the feet of
fmall tlying infects cannot take hold of them, we may eafily con-
ceive that thefe minute hooks, may take hold of the fmall particles
of water or motes from the air adhering to the glafs. And here
we may difcover the error of thofe who formerly fuppofed there
were cavities in glafs, wherein Flies could fix their claws and
climb up.
In the fpring feafon I obferved, on feveral parts of my apple trees,
many caterpillars gathered together, which, in moving from place
to place, fattened themfelves by a kind of thread, and I began to
confider, whether thefe were produced by the black Flies, and it
feems they are called by gardeners de IFolf. To fatisfy myfelf in
this refpeel:, I cut off from the apple tree, two branches, on which
were thefe caterpillars, placing the ends cut off in a veflel of ^^•a-
ter in my hall, in order that the leaves might remain freih, and
xafibrd nouriftiment to the caterpillars : w*hen the leaves began to
Aa 2
( 188 )
wither, I placed frefh branches near the others, to which the ca-^
terpillars remoA^ed themfelves.
When thefe caterpillars came to their full growth, they prepared
to enclofe themfelves in a web fimilar to the filk worm, with this
difference, that at one extremity of their web or cafe, there was a
fmall aperture. A rcprefentation of this web is given at fn;. 20.
Thefe animals, thus inclofed in their web, I put into a glafs tube,
together with feveral others of the fame kind which I had found on
the apple trees, placing the whole in a large glafs. After fome
time, I faw come out of the greatell part of thefe webs certain
white flying infeds, having their wings diverfified with black
fpots ; they were fome\vhat fmiilar to thofc flying animals found in
granaries, and proceeding from the Maggot, which mealmen, and
bakers likewife, call dc If^olf, and of which 1 have treated fully in
another place. I was deflrous of keeping thefe creatures alive till
1 fliould fee whether they would lay eggs, but they all died.
I have eaufed a drawing to be made of this flying animal, as it
appeared to the naked eye, when come out of its web, and this is
to be feen at Jig. 2 1 . To have made a drawing of it from the mi-
crofcope, would have been too troublefome, by reafon of the mul-
titude of feathers with which, not only the wings, but the feet, the
horns, and the whole body were covered, and alfo by reafon of a
crooked organ on the fore part of its head ; the true form and make
of which I was not able to obferve with fufficient accuracy.
Among thefe flying animals, I faw in the glafs two blackifl^
Flies, which I conceived muft have been produced in this manner,
namely, that fome black Fly of the fame fpecies having laid its egg
upon oneof thofe caterpillars, the Maggot thence produced had fed
upon the caterpillar till it had acquired its full growth, and there-
upon was changed into a black Fly, inftead of the web producing
a white flying animal with black fpots.
In one of the glafles, wherein I had inclofed the webs I have
raentionedj there iflucd from thofe webs not only the flying animtvlsr
( 18Q )
• ♦ ■ . . .
I have jnft defcrlbed, but alfo a great number of Flies, fo very mi-"
nute, that I fhould not have imagined they could exift in the open
air, for that the heat mufl caufe all the moill:ure in their bodies to
evaporate.
The fight of thefc Flies caufed me to open all the webs which
had been left in the glafs, and in one of them I found a great
number of minute Ikins or cafes, from which thofe Flies had pro-
ceded by tranfmutation from aurelias. From whence I concluded,
that a minute Fly of this fpecies, muft have laid many eggs in the
aperture of one of thefe v/cbs, and the Maggots hatched from thence,
muft have fed upon the caterpillars in the web, until they came to
their full growth, and then within the web be changed into thofe
mmute Flies ; otherwife, in my opinion, that fpecies of Fly would
become extinct. For we mull lay it down as a truth, that many
flying animals live on nothing but other living creatures, and for
want of which food many of them die, efpecially the fmall ones,
among which may properly be reckoned Flies : for if many Flies
could not find particles of fleili whereon to lay their eggs, the mag-
gots bred from thofe eggs mull perifii.
This innate difpofition and forefight in fmall animals leading then?
to lay their eggs in thofe places where the young maggots may find
food and nourifhment, will appear ftrange to many. But if we
confider the nature of larger fiying animals which are familiar to
us, and that we never fee geefe, ducks^ or fwans, make their nefis
in trees, or in fields far difi:ant from the water, but always on the
banks of ditches or rivers, becaufe they do not bring food to their
young, who are by nature defi:ined to feek it for themfelves ; and
therefore the parents, when the young are hatched, do no more
than tend on them and proteft them from enemies ; whereas, on the
contrary, we fee that birds who arc able to bring food to their
young, build their ncfis on the tops of trees and other high places,
and that the young remain in the nefis, and do not endeavour to
follow their parents, however lumgry they may be, we ll;all ceafe
( 190 )
to wonder, that an infect lays its eggs near the body of anotner,
while in an aureUa ftate, where the young maggots may find nou«
riftiment. And lallly, if we fee in quadrupeds, that many wild
beafts have no other food than the bodies of thofe hearts which
they devour, that there are many birds who feed only upon birdsj
and that the fame almort univerfally obtains in fifties, it will not
appear ftrange to us, that among minute flying animals, fome feed
on others.
I caufcd a drawing to be made of this very minute Ipecies of Fly,
the fize it appears to the naked eye, w hich is fliewn ^tjig. 22, with
a circle round it to make it more apparent ; for I murt confefs, that
when viewing it through the common fpedlacles with which I
write, I could not difcover it to be a Fly. At fig. 23, A B C D, 1
have given a reprefentation of one of the wings of this Fly, as feen
through the microfcope, in order to fbew the wonderful forma-
tion of fo minute an animal. Thefe wings, which are four in
number, are covered both on the edges and on their furface, with
a great number of hairs, terminating in points, Uke thofe on our
hands.
One of thefe minute Flies I placed before a microfcope of much
lefs magnifying power than that from which the wing was drawn ;
by this we fee it to have two pretty horns on its head, each com-
pofed of many joints, and every joint covered with hairs. And
in contemplating the horns, I took notice of the eyes, wherein I
plainly perceived many optical organs of which each eye con-
filled, as we obferve in larger Flies. All thefe objed:5 are rcpre-
fentedat/^. 24, EFGHI.
In contemplating fuch minute animals as this, and confidering
that no part of them is made in vain, but that every one has its ufe,
we fee rtiU further reafon to admire the perfedion of fo minute a
creature. And when we fee the ftupcndous wifdoni of Nature't*
operations in the greatell, and in the lead of her productions, we
may well crj^ out again arid again, *' Away with the blind croakings
( igi )
'' of thofe followers of Ariftotle, who by their writings endeavour
■' to darken the truth, and to perfuade us that flying infects or any
" other aniiTjalcuIes can be produced from corruption !"
There is another fpccies of minute t'ly, which I believe lays its
eggs in ditches, from which maggots are hatched, and thpfe niagr
gets again become flies of the fame kind. I have not thought it
worth while to purfue a minute inveftigation, as to its being fo pro-
pagated, becaufe the fadl is, I think, already fufficiently efta-
blifhed ; but the feathers on its head, its eyes, horns, and wings,
when vievyed by the micro fcope, are fo wonderful to behold, that
I have caufed drawings to be made of fomc parts of it.
Fig. 25, is the Fly of the fize it appears to the naked eye.
Fig. 2(5, is one of the wings viewed by the micro fcope.
Now, if we confider, not only the multitudes of hairs, as
well round the edges of the wing, as in the other honey parts,
xvhich give it ftrength ; and alfo the incredible number of very mi-r
nute hairs with which the membrane of the wing is covered, and
which the limner, as near as he could, imitated in the drawing ;
and that all thefe cannot be compjired with the great number of
hairs with which the Fly's body and its feet are covered ; and if we
naoreqver confider, that each hair is not formed of a lingle velfel,
jaut of many, we muft needs fay, that there is a greater caufe for
admiration and refledlion, in the contemplation of fo fmall infig-
nificant an animal, than in that of a horfe or an ox. And the
deeper we endeavour to fearch iqto the fecrets of Nature, the lefs
we are able to conceive the piinuteriefs of the particles of which
bodies are compofed. And to give {o.n\e idea of which minutenefs,
I have made thefe remarks on the wings of fmall flying animals.
Fig. 27, reprefents one of the two horns on the head of this
fmall Fly.
And here we muft fee, that there is more wifdom, perfedlion,
and curious workmanfliip, in the formation of this fmall Fly I have
( 102 )
teen dercribing, than of the large body of a horfe ; and we alfb'
mnft conclude, which I lay down for certain, that not only this
fpecies of Fly, but every living creature upon the earth, are by no
means produced from any kind of corruption or putrefaction, but
derive their origin from thofe creatures which were made at the
Beginning, or a very fhort time after the parts, whereof our world
confilts, were brought into exiftence. Finally, the more we re-
fled on the confummate wifdom and Ikill of the Creator of the
Univerfe, the lefs are we able to form adequate ideas of his Per-
4-
K)f a vci-ij noxious Animalcule, ivliicJi in tliefpiing infejls tlit -young
Jlioots of fruit trees*
Xi. AVING frequently obferved the leaves at the ends of the young
flioots of goofeberry trees, and alfo on cherry and peach trees, to be
very much contrad:ed, and, as it were, rolled up, by which means
the growth of thole trees was impeded ; and perceiving at the fame
time, many ants on the leaves fo contra6ted, I at firll adopted the vul-
gar opinion, that the ants alone were the caufe of that contradion
in the leaves, and confequently, of the impediment to the growth of
the brartcheSi In one year my cherry trees were fo much infel1:ed
with this contradlion of the leaves, or rather by the Animalcules
concealed in them, that, out of about thirty of thole trees, only two
or three fmall ones were unhurt.
I therefore determined to examine for what purpofe the ants
teforted to thofe young leaves, and what was the caufe of the
leaves being contracted ; in doing which, I faw that the contracted
leaves, and efpecially thofe on the goofeberry trees, were covered
with a great number of dark-coloured Animalcules, and that thofe
which were mod full grown, and were about the fize of a half
grown loufe, were of a darker or blacker colour than the fmaller
ones. Thefe Animalcules were fome of them fo minute, as not to
exceed the flze of a common grain of fand. Upon fight of thefe
creatui'es, I concluded that the ants reforted to the contradled
leaves for no other purpofe, than to devour thefe Animalcules on
them ; and I was confirmed in my opinion, by feeing feveral, both
of the fmaller and larger fort, to be almofl: wholly confumed ; fo
that nothing except their ikins and feet remained.
Vol. II. B b
( 104 )
I cut off a (hoot from a cherry tree, which I brought into my
houfe, in order to examine thele Animalcules more narrowly, and
the rather, becaufe moft of the verniin which infell ouf fruit trees
are, in their refpedtive fpecies, nearly of the fame fize, and are
generated from caterpillars, which become creeping or flying ani-
mals ; and, in like manner all forts of flies, knowm to me, are
generated.
1 again looked over many of the leaves, in order, if pofTible, tq
difcover the eggs from which thcfe Animalcules wci-e produced,
and the rather, becaufe I was certain, that their bodies were not
compofed of annular parts or rings, as is the ca(e with flies, butter-
flies, and the like, which are produced from caterpillars, or mag-,
gots ; and from thofe rings or divilions in their bodies, they have
the name of infecls, among which the flea is alio to be reckoned.
But all my fearch was to no purpofe, at which I was much fur-,
prifed, that among fo many minute animals, not an egg was to be
found. This feemed to favour the opinion of thofe who will have
it, that fmall living creatures are produced fpontancouflv, but fuch
a notion appeared to me altogether impolfible, though, at the fame
time, I was at a lofs how to inveftigate the generation of thcfe
creatures. At length, I determined to open fome of the largefl of
them, in hopes of finding eggs in their bodies ; but, inllcad of eggs,
I 'bund, not without great admiration, young Animalcules in the
bodies of the larger ones, and in Ihape fo like the parent, that one
drop of \vater cannot be more like another, and I extracted not a
fmgle young one, but four, completely formed, from the fame pa-,
rent. Hereupon I judged, that it would be mofl: expedient to cut
off all the twigs and leaves of the peaches, cherries, and goofe-
berry trees which were infefled wdtli thcfe creatures, and thro\v
them into the water to drown them, and try whether I fliould not
aftervNards be lefs infclted with thcfe vermin.
Thefe difcoveries led me to confider, whether thefe Animalcules
towards the end of fummer, or when the leaves fall ofl^, might uot
( 1D5 )
ioflgc tliemfelves in the trunk or branches, of the trees, to flielteJr
themlelves there during the winter ; and, in order to inveftigat^
that mattei*, having a goofeberry tree, which had been fo infefted
with thele animals, that it had grown very little during the fum~
mer, and I had therefore determined to root it up, I fuffercd it to
ftand till the 15th of the following January, when, after a long froll
and rain following, I cut a branch from the tree about a fpan long>
in a place whei-e it was the thicknefs of my finger, and, examining
it by the microfcope, I faw among the cracks in the bark, and
among the fmall dry leaves where the new bud was about to fpring>
and which fall off when the bud grows larger, and alfo among
fome fragments of mols adhering to the branch, feveral of thefe
Animalcules, which all feemed full grown. They were not only
dead, but the hind parts of their bodies were perforated with a
round hole, and their entrails gone, whence I gathei-ed, that provi=-
dent Nature had affigned thefe creatures their enemies, to prevent
their fpecies increaflng too fail, and alfo for the fullenance of other
animals.
In this fearch, I happened upon an Animalcule eight times
fmaller than the' former ones, which moved its liead, horns, and
feet ; and it alfo appeared to me, that it had been produced by
tranfmutation from a maggot or caterpillar, becaufe I could plainly
difcover in it, thofe rings or annular parts we obferve in tnaggots.
i alfo fliw adhering to this branch afubllance, which, upon more
accurate infpe6lion, I took to be the web of fome fmall maggot,
and on tliis were four eggs, the Ihape of birds' eggs, but no larger
than fmall grains of fand, and which I thought might, perhaps, be
the eggs of the before mentioned living Animalcule.
But what to me appeared moll wonderful was, that I difco-
vered two Animalcules, in fliape like thofe called by children
lady-birds, but fo minute, that a hair taken from my hand, was
more than four times their thicknefs, and, upon comparing them
with a grain of fcowering fand, it was, in my judgment, three
Bb3
( IQQ )
hundred and fifty times as large as cither of them : one of thefe
Animalcules was alive and moved its feet, and I was certain it vvus
of full fixe, bccaufe it appeared to have been produced from a
maggot : and 1 the more wondered at the figiit of fo minute an
animal, becaufe I could not have imagined fo fmall a creature
could live in tlie open air ; for, if v»e fuppofe the one hah ot this
animal's body to confiil of a thin or watery fublhmce, one would
conclude, fo fmall a quantity would be foon evaporated ; but yet,
when we find that fo Imall an Animalcule remains a long time
alive, we mull conclude, that Nature, our kind and provident mo-
ther, has formed the Ikin of this animal lb hard and fuhd, that litrs
tie or no moiliure can be evaporated from it,
Thefe were my obfervations during one fummer and the winter
which I'ollowed. On the 17 th of May in the following year, I did
not find, among all my goofeberry trees, above three or four
branches the leaves of which were contradled. Upon opening thofe
leaves, 1 found eight or ten of the before mentioned Animalcules,,
and among them one of a dark colour, inclining to black, and larger
than the relL This, on account of its fize, I judged to be a fe-.
male ; and upon opening it. 1 took out of the body twenty-one
young ones, of which one feemed to be completely formed, and
of a lighter green colour than the parent; the others were of fuch
diflcrcnt fizes and colours, that in the fmallefl, I could neither dif-
tinguifh the eyes, nor the green colour.
I opened feveral other of thele Animalcules, which I deemed to
be females, and took out of their bodies many young ones ; in fome
more than thirty, and in none lefs than twenty, of different fizes,
and fome fo fmall that I could neither difi;inguith their limbs nor
eyes.
On the 20th of INIay I cut off three branches of this year's growth
from a goofeberry tree, on which branches I was certain there was
no animalcule of this fpecies ; thele I put into a vellel of water, and
on the tops of two of them I put t^^'o and on the third branch tlu'ec
( 197 )
of thofe Animalcules, which I deemed by their fize to be females, ia
order to lee how loon, and to w^hat degree, they would bring forth
joung : and, in twenty-four hours, two of thefe produced nine
young ones and a third lix ; they continued to increafe, but there
being a vefl'el, with flowers in it, brought out of the garden, which
liood near that M'here the branches were, fome ants, which were
among the flowers, crept into the branches and killed fome of the
Animalcules, for I could plainly fee that their bodies had been, in
great part, devoured by the ants. Hereupon I killed all thofe ants,
and placed the veflel containing the branches in a dilh full of water,
to defend the accefs to it from ants.
In thefe and others of my obfervations it appeared to me that our
common ants, which I had always deemed Aery pernicious infects,
on account of the damage they do in our gardens, by devouring the
fruit when ripe, do. on the contrary, in the fpring, when there is no
fruit, live upon other fmall creatures ; lb that I am doubtful whe^
ther the damage they do is greater than the utihty they are of in the
fpring.
Hereto I mull add, tliat I have been at fome times very much in*
felled with ants, fo that I caufed them and their eggs to be dug up
and thrown into the water : but afterwards my method was, where
an ants' nell was found, to ciuse its opening to be llrongly preifed
cjovvn with the foot, to deftroy the ants in their nell ; and, if ants
were found among the trees, to llamp the earth dole round the trees,
in order to keep the ants within the ground, and prevent their bring-
ing food to their young, whei-eby both would be dellroyed, and by
this means I almoll wholly freed myfelf from them,
On the 30th of IVIay I again examined the branches I had placed
in my lludy, and found many young Animalcules on them, fome of
"which were confiderably grown ; and I alio perceived that it was in
the nature of thefe creatures to change their ikins, for I found fe-
veral call Ikins, in which I could plainly fee the feet, horns, hairs,
and claws on the feet j and in thefe Ikins, which were very tvanf"
( m )
parent, I not only favv many veflels, but I could difcover many cf
the eyes, or optical organs, w ith which this creature is provided, all
which were a plcafant IpecHiacle to behold.
Hitherto 1 had been of opinion that thele Animalcides fed only on
the veins or veflels of the leaves, and that their breaking or biting
them caufed the leaves to Contract, and under which contra('l;ed
leaves the animals llieltered themfclves from the heat of the fun ;
but now I faw that they, for the moll part^ fed on the very fmall
buds and alio on the Ihdks of the leaves, the velTels of which being
wounded caufed the leaVes to contrail in their growth, and the nou-
rilhment from the young flioots being, in a great meaftire, taken
away, the flioots grow knobbed and crooked.
Upon recoUeding that, in the former fummer, I had feeri on my
plums and apple trees a great number of flics which, as I thought,
had fo imJDeded their growth that not only the apples wefe very fmall,
but alfo the young flioots were very defective, I now determined to
examine into the true caufe of that appearance.
I could not, in my fearch, difcover any eggs of thofe flies in my
apples, peaches, and plum trees, but I now faw all the young flioots
bf one of my goofeberry trees to be uncommonly contracted, and oft
it I not only faw a great number of thofe Animalcules I have de-
fcribcd, which breed their young within them, but alio many black
flies, whole bodies were not larger than the bodies of those Animal-
cules. I therefore pulled up the tree and threw it into the water,
concluding it impoflible to extirpate all the Animalcules and lave the
tree's growth, having firll cut ofi' two branches of it for further ex-
amination.
Thefe flies have four wings, the two largefl: of which are twice
the fize of their bodies ; I could not, at firll, think they were pro-
duced from the other Animalcules, but, upon examining them by
the microfcope, I found the bodies of both of them to be veiy flnii-
lar, and, after feveral repeated obfervations, I law that the firfl: men-
tioued Animalcules had, on each lide of their bodies, a long >n bite
( 100 )
protuberant part, ■\^'hich, upon examination by the microfcope, 1
found to be wings. I alfo opened the bodies of feveral of the flies,
and in them I found young ones of the fame form, and in like nxnn-
bers, as the other Animalcules, all which plainly proved to me that
thefe Animalcules, commonly called goofeberry lice, are changed
into flies.
As I was aflured that the Animalcules which had been bred in my
houfe, and were now fourteen days old, had grown to their full fize,
I opened three of them, and from the body of one of them I took
about thirty young ones, of different lizes, from another forty-nine,
and from the third fixty. At this very great increafe I was afloniflaed,
and was deflrous to examine all the goofeberry and other trees in my
garden, in order to extirpate thefe noxious animals as much as pof-
fible; and the rather, becaule when changed into flies, they can fly
into other trees, and fo infe<5t the whole. But though we may clear
our gardens ever fo much, they will be ftill liable to be ipfefted fron^
neighbouring ones.
' Some of thefe Animalcules, whofe change I judged was near, I
put into a glafs, in order, if pofllble, to obfcrve the nature of fuch
change ; and, after a day or two, I faw one of them put otF its flcin
and aflume a new form : its wings, which before had been folded up
very clofe, it expanded by degrees, fliaking them flightly, and then
they appeared as fl:raight and regularly placed as if they had never
been folded up, and the fame I obferved in others.
This kind of propagation appeared to me more wonderful than
any I had before oblerved ; if we confider that fuch minute Animal-
cules, as thofe we are now confidering, fliall, within thirteen days
after they are produced from the parent, breed within them fixty
young ones, many of which can be feen to be completely formed ;
and moreover that thefe Animalcules, after iflliing from their parent,
fliall, in their growth, many times change their Ikins, produce
a number of young, and lallly be changed into flying animals which
pontiaue to bring forth young; this niull appear wpnderful, and be
( '206 )
a Confirmation of the principle, that all living creatures deduce their
origin from thole which were formed at the Beginning.
And if we compute how many Animalcules one female may pro-
duce in the courfe of a liimmer, reckoning from thofe ws find in
their hodies, w ithout conlidering thole that efcape our notice, we
muft be filled with afi^onifhment.
Although thefe Animalcules were propagated fo rapidly in my
houle, as I have before fet down^ I have found that in the open air
they increafe flill fatier.
I have alio obferved another fort of thefe Animalcules^ a littld
different from the former, for the bodies of the former \\ ere not only
fomewhat broadci% but, when 1 examined their heads and the hind
part of their bodies by the microfcope, I found that thofe parts were
alio different: for the former, when full grown, had a dark colour,
appearing blackifli ; the latter were green, and fo were the flies pro-
duced from them. I alio fiiw thefe two fpecies of Animalcules mix
one among another, whence I concluded that they were the two
iexes.
As foon as the young of thefe Animalcules come from the pa-
rent, they can creep about, and appear as vigorous, as if they had
been long in the open air.
I havecaufed drawings to be made of thefe Animalcules, in ordei*
to ihew the exadt regularity and perfedion which are fhewn in the
formation of fo contemptible a creature.
Plate XVI. fg 28, reprefents one of thefe Animalcules of a light
green colour, the fame fize it appeared to the naked eye. Fig. 2g
A B C D E F G II, is the fame fecn through the microfcope, being
of its full growth and approaching to its change ; the wings, folded
together, begin to appear, and may be fcen in the figure at W X.
At KLMN, are the fix legs with their joints, covered with many
very thin and fliort hairs, and each of the feet furnilhed with two
claws. At F, is one of its two beautiful eyes, the wonderful for-
mation of which, as it appeared through the microfcope, tlie limner
( 201 )
could not copy in the draAving, 1 1, fhews the trunk, or piercer,
which the animal ftrikes into the bud, or ftalk, on which it feeds :
F Z Z, are the two horns.
In the hind part of its body this Animalcule has two parts, or or-
ga'ns, thicker in the middle than at the ends, which are curioufly
covered with round fcales, placed in exaft order befide each othef
thereon, as fhewn at C and B, and from thefe organs I often faw a
fmall drop of very tranfparent liquor ilTue, as lliewn at B. This fmall
drop exhibited a very pleafant fpedacle to me, for, when removed
a little further from the microfcope, it had the effe6l of another mi-
ox-ofcope, fliewing the objects, as houfes, fteeples, and the like, in-
verted, and fo minute and delicate in their appearance, that could
fcarcely be believed. When this drop of liquor was emitted from
one of the organs, B or C, I faw that the organ from which it if-
fued was immediately drawn in towards the animal's body.
D T U E, is the point of a needle, to which this animal was
faftened when the drawing was made.
Fig. 30, is the fame Animalcule, of the lize it was when changed
into a fly.
While the limner was employed in making the above drawing, I
dilTedled fome more of thefe Animalcules, and having taken out fome
of the unborn young ones, I placed the moft perfedl one of them
before a microfcope, and caufed a drawing to be made of it, which
is fhewn at Jig, 31, OP: this animal's body appeared to be covered
with a membrane, but the limner could not copy in his drawing all
the parts which were to be feen, becaufe the moifture of it in a very
fliort time evaporated, and thereby the fhape was altered. I alfo
gave the limner another microfcope, before which I had placed eight
unborn Animalcules, in all which the eyes could plainly be feen,
and of thefe he made as corred a drawing as he was able, which is
Ihewn at fg. 32, Q R S.
In fg. 28, at F, I have fliewn one of the curious eyes of this
Animalcule, but meeting with one of the put-ofF Ikins, in which
Vol. IL C c
( 202 )
the formation of it could be feen more accurately, I placed it, by
itfelf, before a microfcope of greater magnifying power, and caufed
a drawing of it to be made, in order to Ihew the perfection exhi-
bited in fo minute, and to us fo defpicable, a creature. Fig. 33, A B,
reprefents this eye as {een in the put-ofF fkin, and it appears to be
compofed of a great number of diftindl eyes or optical organs.
After this I opened the bodies of others of thefe Animalcules, in
order to fee whether the young ones within them lliewed any ligns
of life, and I found one of the young Animalcules, in whofe body
I could not only fee the motions of the inteftines, but alfo its feet to
move, though they lay regularly placed on the fides of its body.
On the 6th or 7th of June, I faw that many of the Animalcules,
which had been brought forth on the 2lft of May, were changed
into flies, and feme of the leaves on the goofeberry branches where-
on I kept them began to wither.
Until the 5 th of June, I had often fought for thefe Animalcules
on my cherry, peach, and plum trees, but found none : on the 7 th
of June, upon making a farther fearch, I found fome of them on
fourteen different branches of the cherry trees; they were not green
but blackifh, the young ones round about them were of a dark co-
lour, and in one leaf I faw five Animalcules, full grown, which
had one hundred young ones round about them.
I opened many of thefe Animalcules, and took many young ones
out of them of the fame kind as before mentioned, but thefe laft
young ones were of a dark colour. I alfo opened fome Animalcules
ly^hich feemed to be half grown, and found in them many imperfedly
formed young ones, and, to the befi: of my judgment, 1 counted lixty
in the body of one of them, befides which there were doubtlefs many
which I could not difcern ; the largefl: of thefe were of a green colour.
I did intend here to have finiflied my obfervations, but feeing
that thefe laft mentioned Animalcules were only on the cherry trees,
and perceiving fome little differences in their formation from thofe
I have befoje mentioned, I determined to try whether thefe lafl
( 203 )
would feed on the goofeberry tree ; I therefore took three
branches of this year's growth from a goofeberry tree, which I put
into a veflel full of water, and put on each of them a cherry tree
leaf, whereon were many of thofe Animalcules, judging, that as the
cherry leaves began to wither, they would leave them and remove
to the goofeberry leaves, which they accordingly did. But they did
not remain clofe to each other, as they had done on the cherry
leaves, where they had food clofe to them, but difperfed themfelves
among the goofeberry leaves, creeping up and down among the
branches, I then put two twigs of the cherry tree in the veflel clofe
to the goofeberry branches, and faw many of the Animalcules quit
the goofeberry and remove to the cherry branches ; thofe which
did not remove to the cherry branches, I found afterwards dead ;
others got down to the water and there perilhed.
On the 23d of June, I was much furprifed to fee a great nuni-
ber of the Animalcules Hill remaining on the cherry branches, and
on the 20th, I faw fome of them changed into flies ; but what I
mofl; wondered at was, that fome of the Animalcules, which I
judged had lived through the whole winter, were not yet changed
into flies.
I obferved, among other things, that as foon as one of thefe
Animalcules had put off its Ikin, and w^as changed into a fly, it
immediately began to move its wings, whereby they opened a little
from the fides of their bodies, to which they before were clofely
attached, and in the fpace of two minutes acquired their full fize ;
and, at this time, I thought I faw the parts of the wings not only
unfold, but alfo encreafe in fize.
Moreover, I opened fome of the Animalcules which were
changed into flies, and took feveral young ones out of their bodies ;
thefe animals had alfo a piercer, which they thrufl; out of the or-
gan, fig. 28, 1 1, and which is there fliewn at I A: this is put off
with the ikin when they undergo their change.
Cc 2
( 204 )
Another circumftance appeared to me particularly worthy of note,
that I law about fifteen of thefe Animalcules, whofe bodies were fo
fwelled, that they feemed almoil globular : fome of them were
dead, others moved but little, and upon opening them, I found
their Ikins very tough, compared with others of the fpecies, and
on the inhdes I found no appearance of any young nor any bowels,
but only a white thick maggot, which took up almoil all the fub-
ftance of their bodies. 1 put twelve of thefe, fome of them living,
others dead, into a glafs, and in a little time they were all dead.
But after eight days, namely tlie 24th of June, I opened one of
them, and took out of it a hving maggot, which lived for the
fpace of thi'ee days in the glafs wherein I put it : this maggot ap-
peared to me, like thofe produced from the eggs of ants ; for like
thofe maggots, it feemed incapable of moving from place to place,
as it had no other motion than what confilled in extending and con-
tracing its body in a fmall degree.
I was atlonifhed at this fpectacle, refpe^ling which I could form
no other conjedlure, than that thefe Animalcules had been impreg-^
nated by a female ant laying its egg in the hind part of the animal's
body, which is the only way I could conceive that the maggot
from an ant's egg could be found in that place.
I opened feveral others of thefe Animalcules, at different timeSj
and found maggots in all of them ; but I could not, in any inftance,
extract the maggot without injuring it. I left fome of thefe Ani-
malcules which were dead in the glafs, and after a few days, I
found that the maggots within them were dried up.
On the 20th of June, I found on a plum tree, on which I could
not for three days before difcover any, a great number of green
Animalcules, the largeft of them about the lize of a common loufe,
and with which fome of the leaves were fo covered, that their lur-
face could not be feen, and this for the molt part by Animalcules
but lately brought forth.
( 205 )
I took a leaf on which were only two large ones, and two or
three young ones, fuppollng that the full grown ones had not yet
brought forth many young ; one of thefe I opened, in order, if
poffible, to compute the number of young I might take out of it,
and I thought that the young which I could dillinguilh, and thofe
particles which I confidered to be young ones yet unformed, ex-
ceeded the number of feventy.
At the fame time, I law, among many others, fix Animalcules
changed into flies, in all which I found, upon opening them, a great
number of Animalcviles, and, among the reft, one that was upon the
point of being voided by the parent; and 1 not only faw it move,
but I could fee the inteftines within it move about as vehemently as
if it had been a parcel of living creatures.
But what feemed to me the moll extraordinary of all my obferva-
tions was this : that in every one of the Animalcules which I opened,,
thc-ugh but of a middling fize, I found young ones, and alfo upon
opening fome whofc bodies were very flender, and which, for that
reafon, I thought might be males, yet among thefe and all others
of the Animalcules, I have been defcribing under this head, I could
not find any that could be deemed males.
Farther, I opened fome Animalcules, which were about an eighth
part the fize of the parent ones, and I took out of them a great
number of round and pellucid particles, which, I doubted not,
would in time have become perfedl young ones ; fome of the
largeft of thefe contained fome green particles, and moreover, they
were of different fizes, the fmalleft of them appearing no larger
through the microfcope than a grain of fand viewed by the
naked eye.
I afterwards opened fome Animalcules twenty-four times fmaller
than the full grown ones, and in them I alfo faw fome of thofe
round particles, which I concluded would in time become young
ones ; and fi.nally, I opened one, which was not much larger than
( 20fi )
thol^e newly voided by the parent, and, in my opinion, was only
one day old ; but I was not able to Judge with certainty, relpefting
the particles which I took, out of its body, (by reafon of their ex-
ceflive minutenefs), whether they were fuch as would in time be-
come young animals.
Addition, by the Translator.
THE Tranflator hopes to be indulged in bearing his teftimony to the
accuracy of Mr. Leeuwenhoek's inveftigation of the preceding fubjeft, and
alfo as to the utility of his difcoveries.
This part of the tranflation having been made at thehoufeofa friend in
the country, and in the month of June, the Tranflator was led to examine
the fruit trees in the garden, cxpefting to find fomeof the Animalcules men-
tioned in this Effay : he faw many of them exa£lly agreeing with tlie de-
fcription here given; on the goofeberry and currant trees (particularly the
latter) they faftened themfelves at the extremities of the young flioots, and
the farther extenfion of the flioot feemed to be entirely prevented, for the
bud in the centre was deftroyed and the ftalk of the fhoot grown into an ir-
regular knobbed form, and fwelled to two or three times its natural fize,
having the fame appearance as a gouty limb.
Some perfons may perhaps be difpofed to ridicule the great pains taken by
Mr. Leeuwenhoek to inveftigate the nature of fo minute, and, as they
may think, fo contemptible a creature, as that under confideration.
But the ftate of the fruit trees juft mentioned will at once demonftrate that
thefe minute animals are of a formidable nature, and capable of deftroying
all the next year's produce- For if they attack the young fhoots in the early
part of their growth, and thereby put a flop to their further vegetation, the
confequence muft be that from thofe trees, whofe fruit is produced upon the
lafl year's wood, little or no fruit can be expefted in the fucceeding year.
On certain Animalcules found in the fediment in gutters on the
roofs of houfes. *
1 HAVE been induced to publifh my difcoveries refpeding thefe
creatures, in order to fliew how wonderfully Nature has provided for
the prefervation of their fpecies.
On the 25 th of Auguft, I faw in a leaden gutter at the fore part
of my houfe, for the length of about five feet, and the breadth of
leven inches, a fettlement of rain water, which appeared of a red co-
lour ; and, upon confidering that perhaps this colour might proceed
from fome red Animalcules, fimilar to thofe which I had feen in
muddy ditches, I took a drop of this water, which I placed before
the microfcope, and in it I difcovered a great number of Animal-
cules, fome of them red, and others of them green. The largeft
of thefe, viewed through the microfcope, did not appear bigger than
a large grain of fand to the naked eye ; the fize of the others was
gradually lefs and lefs : they were, for the moft part, of a round
fhape ; and in the green ones, the middle part of their bodies was
of a yellowifll colour. Their bodies feemed compofed of particles
of an oval fhape ; they were alfo provided with certain fhort and
llender organs or limbs, which were protruded a little way out of
their bodies, by means of which they caufed a kind of circular mo-
tion and current in the water : when they were at reft and fixed
themfelves to the glafs, they had the Ihape of a pear with a ihort
ftalk. Upon more carefully examining this ftalk, or rather this
tail, I found that the extremity of it was divided into two parts,
• This fpecies of Animalcule is very minutely defcribed by Mr. Baker, in his Treatifes
on the Microfcope, and he has gtren to it the name of the wheel aoiaal : alfo ia Adams on
the Microfcope,
( 208 )
and by the help of thefe tails the Animalcules fixed theinfclves to
the giafs ; the lefler of thefe appeared to me to be the offspring of
the larger ones.
Moreover, I faw another kind of Animalcules much fmaller, the
bodies of them were very tranfparent ; but there feemed to be an
hundred of the former fpecies to one of them.
On the 3 111 of Augull, the M'ater which I had before obferved,
was, by three fucceffive days of hot weather, fo dried away,
that when I prefled my finger on the muddy fcdiment in the gut-
ter, no more water than about the fize of a grain of fand adhered
to my finger, in which water I difcovered a fmall number of tranf-
parent living Animalcules, but all the green and red ones were
dead.
The fir/l of September the fcdiment in this leaden gutter was fo
thickened, that it appeared like Giff moill clay ; but, vath all my
endeavours, I could not difcover any Animalcules in it of the fpe-
cies I had before feen.
At length 1 difcovered two living Animalcules with oblong bodies,
like the largell of thofe which I had formerly feen in rain wvttev,
wherein pepper or gingei" had been infufed. Thefe Animalcules
were almoll: the thicknefs of a hair of one's head.; but fuch of
them whofe bodies were full of young, were twice that fize, the
ends of their bodies terminating in a point ; their tails were pro-
vided with fix or eight minute organs, by the help of which they
could fallen themfelves to the glafs, and the fore part of their bo-
dies being alio provided with certain organs, when they would move
from place to place, they brought their hind parts nearer to th«
fore part, and then, loofing the fore part, they extended it in like
manner as we fee caterpillars do ; and, in fwimmiug, they made ufe
of other organs defiiined for that purpofe. Soon afterwards I ob-
fcrvcd many of the fame fpecies of Animalcules.
The matter in the bowels of thefe creatures was for the raoft part
red, proceeding (as I imagine) from their feeding on fmaller Ani-
( 209 )
flialcules of that colour, but fome few of them had no red colour
in them, efpecially the fmaller ones, which probably had not been
long brought forth from the parent.
On the fame day the weather was very hot, and, in the afternoon,
I took a fmall part of the fediment from the gutter which was now
quite dry, and I faw the furface of it completely red, by reafon of
the great number of red Animalcules in it, being many more than
the green ones ; but I could not diliinguifla them until 1 had moifl-
ened the fubftance with fome rain water.
The following day the Iky was again very hot and dry, and, about
nine in the morning, I took fome of the fediment which had been
in the leaden gutter, which was then quite dried, and no thicker
than half the back of a knife ; it had alfo lain from the preceding
evening in my lludy ; this I put into a glafs tube, about the thicknefs
of a fwan's quill, and poured on it a fmall quantity of rain water
taken out of my ftone cittern, in which water were fwimming fome
of the before mentioned Animalcules of the fmaller fort ; having
poured in this water, I mixed it up with the dry fediment or matter
put into the tube, and which feemed very hard and compadl, in or-
der to dtirolve the fame ; that thus, if there were Itill any living
Animalcules in it, they might illue forth ; though I confefs I never
thought that there could be any living creature in a fubftance fo
dried as this was.
I was, however, miftaken ; for fcarce an hour had elapfed, when
I faw, at leart, an hundred of the Animalcules before dcfcribcd; fome
of them adhering to the glafs, fome creeping along upon it, and
fome fwimming about. In the evening I computed there were
more than three hundred of the fame kind of Animalcules, but the
moft of them were not of full fize, as I judged by their bodies be-
ing fo minute, and fo empty of food, as if they were newly born ;
and in the bodies of fome of the larger ones, I could fee two, in
others three, young ones, folded double : thefe young ones, when
Vol. II. D d
( 210 )
newly born, were as quick in their motions as the full grown
ones.
In that part of thefe Animalcules which may be called the breaft,
• 1 faw a round particle moving with a reciprocal contrad;ion and di-
latation, in the time one might count one : this I did not doubt
was the heart.
Moreover, the fore part of the bodies of thefe Animalcules, which
may be called the head, was divided into two parts, each of the two
divifions being of a round Ihape, fet round with certain long and very
llender organs, which, in their motion, exhibited a moll: pleating and
delightful fpedlacle ; to form an idea of which, we mull; fuppofe we
fee two Imall wheels fet round the edges with fliarp points or pins,
and thefe wheels in fwift motion, as it were, from the Weft towards
the South and Eaft, but never to move in a contrary dirediion
from the Weft towards the North and Eaft.
This fpe6lacle appeared to me the more wonderfiil and incom-
prehenfible, becaufe it is not to be conceived how fuch a motion
can be produced or performed in an animal body.
In order to give a clearer conception of this, I took a glafs tube
with fome of thefe Animalcules in rain water, which I placed before
the microfcope, and delivered the fame to the limner, that he might
make as exadl a drawing of it as he was able.
Plate XVI. Jig. 33,ABCDEFG reprefents one of thefe Animal-
cules, which had fixed itlelf to the glafs by the help of the limbs or
organs at A. The round oblong particle, appearing between B and
G, I take to be a portion of its food nearly digefted ; that which is
fituated in the middle, I think is the food in theftomach and intef-
tines ; and the four oblong particles which feem, as it were, to fur-
round the inteftines, exhibit the young Animalcules in the body of
the parent.
Between the letters D and E, appear the two round parts, fliaped
like wheels, with fliarp points placed upright on them. Thefe
( 211 )
wheels moving from the point D, which we will call the Weft, and
carried round, with a very fwift motion, by the South towards the
point E, which we will call the Eaft.
When one of thefe Animalcules is creeping along the glafs, it
affumes the figure H I K L M N O, fg. 34 : the parts, H and M,
being alternately fixed to the glafs, and in this lltuation the organs,
like wheels, which in the former figure are ftiewn between D and
E, are drawn within the body, and a part like an horn, marked L,
appears in fight. Befides thefe pofitions, the animal twifts and
turns its body into fuch wonderful Ihapes, that I have often been
afl:oniftied to behold it.
The limner alfo faw feveral Animalcules of a fliape fimilar to
what is reprefented at fig. 35, P Q ; thefe had the lower parts of
their bodies of a flat fliape, from which iflued various minute or-
gans, which they ufed in moving themfelves from place to place.
Now in the body of this Animalcule, were many globular particles,
and in the fame water were many ftill fmaller Animalcules, whofe
whole bodies appeared no larger through the microfcope than one
of thofe globules in the former Animalcule.
I have often placed the Animalcules I have before defcribed out
of the water, not leaving the quantity of a grain of fand adjoining
to them, in order to fee whether, when all the water about them
was evaporated and they were expofed to the air, their bodies would
burft, as I had often feen in other Animalcules. But now I found
that when almoll all the water was evaporated, fo that the creature
could no longer be covered with water, nor move itfelf as ufual,
it then contracted itfelf into an oval figure, and in that fiiate it re-
mained, nor could I perceive that the moifl:ure evaporated from its
body, for it preferved its oval and round fhape unhurt.
In order more fully to fatisfy myfelf in this refpeCi, on the third
of September, about ieven in the morning, I took fome of tiiis dry
fediment, which 1 had taken out of the leaden gutter and had llood
almoft two days in my lludy, and put a little of it into two feparate
Dd2
( 212 )
glafs tubes, wherein T poured foine rain water which had been boiled
and afterwards cooled.
This fediment confifted of a fmall portion of earth, fome fand,
pieces of mortar ; and among it were mixed fome pieces of hair,
threads of wool of different colours, and bits of ftraw, which things
we may fuppofe to have been brought thither by the winds ; and
the furface of it conlifted of thofe red and green Animalcules, ap-
parently dead.
As foon as I had poured on the water, I ftirred the whole about,
that the fediment which, by means of the hairs in it, feemed to ad-
here like a folid body, might be the fooner mixed with the water :
and when it had fettled to the bottom of the glafs, I examined it, and
perceived fome of the Animalcules lying clofely heaped together. In
a Ihort time afterwards they began to extend their bodies, and in
half an hour at leaft an hundred of them were fv^imming about the
glafs, though the whole of the fediment which I had put into it did
not, in my judgment, exceed the weight of two grains. After five
or fix hours had elapfed I faw two feveral forts of Animalcules f\\ im-
ming in the water, the leaft of which were fo minute, that many
thoufands of them would fcarcely equal the fize of a grain of fand.
The preceding experiment I afterwards repeated, and met with
the fame event.
Thus we fee that thefe Animalcules, when the water dries away,
contrail their bodies into an oval Ihape, and, even in the heat of
fummer, preferve their oval lliape for a long time : and, that when
they are again fupplied with water, they, in a very little time, unfold
and extend their different limbs or organs, ufing them in the fame
manner, and with the like motions as they did before the want of
water caufed them to contraft themfelves. And this I obferved, not
only in the full grown ones, but in the moft minute of thofe Ani-
malcules.
Hence we may conclude, that in like manner as the fhells of the
eggs of moths or butterflies, whence caterpillars are hatched.
( 213 )
and alfo the membranes of grubs or cryfales produced from cater-
pillars, are of fuch folidity and firmnefs that the moifture in them
will not evaporate, fo the Ikins of the Animalcules I am now treating
of are formed of fuch a folid texture, that they do not permit the leaft
evaporation : and, were it not fo, I will venture to affirm that thefe
creatures in very dry weather, being deprived of water, mull all
perifh : and this, M^hich we find to be the cafe with thefe, we may
fairly conclude takes place with Animalcules a thoufand times lefs.
We can now ealily conceive, that in all rain water which is col-
lected from gutters in cifterns, and in all waters expofed to the air.
Animalcules may be found, for they may be carried thither with the
particles of dull blown about by the winds. And not only fo, but
Animalcules, millions of times fmaller than a grain of fand, may
be carried up in particles of water, if not to the clouds, yet to fuch
a height as to defcend with the evening dew : or by the winds they
may be raifed from the earth, and fpread on all fides. Nor will this
appear incredible, if we confider that, in great llorms, the fea water
is dafhed with fuch force againll the Ihore, that the particles of it
are carried many miles, fo as by fettling on the leaves of trees and
herbs to give them a fait talle.
The preceding kinds of experiments I have many times repeated
with the fame fuccefs, and in particular with fome of this fediment,
which had been kept in my lludy for above five months, and upon
pouring on it rain water, which had been boiled and afterwards
cooled, I faw in a few hours time many of the Animalcules before
defcribed. And if, after being fo long in a dry llate, thefe Animal-
cules, upon water being given to them, can unfold their bodies and
move about in their ufual manner, we may conclude, that in many
places, where in fummer time the waters llagnate, and at length dry
up, there may be many kinds of Animalcules, which, though not
originally in thofe waters, may be carried thither by water fowl, in
the water or mud adhering to their feet or feathers.
( 214 )
From all thefe oblervations, moft plainly we difcern the incom-
prehenfible perfeftion, the exadl order, and the infcrutable provi-
dential care with which the moll wile Creator and Lord of the Uni-
verle, has formed the bodies of thefe Animalcules, which are fo mi-
nute as to efcape our fight, to the end, that the different fpecies of
them may be preferved in exillence. And this moll wonderful dif-
polition of Nature with regard to thefe Animalcules, for the prefer-
vation of their fpecies ; at the fame time that it ftrikes us with allo-
nifliment, mull furely convince all of the abfurdity of thofe old opi-
nions, that living creatures can be produced from corruption or
putrefadlion.
On the circulation of the blood in the tail of an Eel, and in the tails
and fins of other fflies : ivith a particular defcription of the Au-
thor s apparatus for viewing it,
x\MONG * other objeds, wherein I have viewed the circulation of
the blood, was an Eel, and in the fin of its tail, I faw the blood cir-
culating through an incredible number of arteries and veins of vari-
ous fizes; and although thofe blood-veflels were difperfed promif-
cuoully one among another, yet I could very plainly diftinguilli the
arteries and veins.
Upon fixing my eye almoft at the extremity of the tail fin, I
there faw fuch a number of minute blood-veflels, that it was impofli-
ble forme to difcern the circulation in the minuteft of thofe veflels.
This fjn being a little dirty, I took a piece of linen cloth, and gently
wiped it twice, to get a better view ; but I found that in that flight
touch, many of the external blood vellels were fo injured, that many
particles of blood iflued forth, caufing the extreme parts of the fin
to appear red, and they were alfo a little diftorted : I alfo plainly
faw in all the arteries, however minute, a fi:rong and quick fuccel-
five elevation, with a protrufion of the blood ; and, upon attending
to a large artery in the tail, I there faw the protrufion of blood, de-
rived from the heart, to be much more vehement.
I alfo placed before my fight one of the two fins which the Eel
has next its head, and there I faw the blood circulating in as many
diftindl places as I have jufl; mentioned refpefting the tail fin. And
when I endeavoured to purfue the circulation to the extremity of this
• See more on this fubjeft, in Vol. I. p. 89. et m*?.
( 21C )
fin, I there faw its motion, both in arteries and veins, in fuch an
inconceivable number of cxcelTively minute veflels, that it looked
as if the fin in that part of it was compofed of nothing but blood
velfels.
In this and many other Eels, I faw that the blood veflels, where
the circulation comes to its full extent at the extremity of the tail
fin, turned back with a fmall bending, many of them taking their
courfe tranfverfely, or eroding one another, in their return back
towards the heart. For inllance, the circulation appeared to me
as in Plate XVII. Jig. 1, A B C D E, which reprefents a blood-velTel
fituated between two of tl\ofe fmall bones which give ftrength to
the extremity of the tail fin. In this figure, ABC is to be called
an artery, becaufe in it the blood moves forward from A by B to-
wards C, and from C by D, it returns to E ; therefore C D E mull
be called a vein, though each of thefe veflels, fo called, is but one
and the fame blood-vefl'cl prolonged ; and in its return it twice
crofles itfelf. Near to this was one of the linall bones of the fin,
and clofe to it a lecond blood-veflel, in which alfo the circulation
forward and backwards was performed ; and this veliel in its return
alfo twice croll'ed itfelf, but with fomewhat fmaller bendings than
in the other vefTel. Here, F G H, is an artery, wherein the blood
was carried forward as far as H, and, bringing back the blood to-
wards the heart, in the direction H I K, it is then to be called a
vein. On this occafion I faw, (and which I had obferved in feveral
other infiances) that in the firll mentioned artery ABC, there
arofe, at C, a fmall veli'el which conveyed the blood from ABC,
into the other veliel at I.
To give an idea of the relative fize of thefe vefTels, and of their
■dillance from each other, the reader will underliand, that the dif-
tance from E to K was almoll equal to the breadth of four hairs of
one's head.
To make thefe obfervations, my method at firfl: was, to wrap the
Eel in a piece of paper, or a cloth, leaving out only that part of
( 217 )
the fin which was to be examined ; but, with all my care, I found
that, in doing this, I either impeded the circulation or injured the
iin ; I therefore adopted this method : to take Eels about the
Hze of one's finger, and let them fwim about in the water for a
time, till they were at reft, and then examine their tail fins while
in the water, for in that fituation they fpread out their tails, but
when taken out of the water, the veiy extremity of the fin gathers
up in wrinkles. '
In order to impart this pleafing fight to others, I invented and
compleated fome inftruments, whereby I exhibited the fame to fe-
veral gentlemen of eminence in this country, who all declared,
that they did not think any more delightful fpeclacle, nor more
worthy of obfervation could be lliewn.
I have determined to give drawings of the inftruments by which
I exhibited this circulation of the blood, and by which thofe who
defire to view the fame may be eafily gratified.
I firft prepare a piece of brafs about half the thicknefs of the
back of a common knife, and of the fhape reprefented at fig. 2,
A B C D E F ; this I hammer upon an anvil fome time, to make
it the tougher, and make two large holes in it, as fliewn at G H I
and K L M. I alfo drill fix fmaller holes at P Q R S and NO. I
then bend this piece of brafs at the end A B F, and at the dotted
line B F, fo that it may form a right angle with the other part, and
alfo bend the other end C D E, in like manner.
I then take another flat piece of brafs of the fame thicknefs,
which, being well hammered, will anfwer the purpofc of a fpring ;
this is reprefented ^tjlg. 3, A B C D, and I haminer it into feme-
thing of a hollow fliape, and file in the lower end of it a cavity,
in order that it may in part furround the glafs tube I flaall hereafter
defcribe ; this round cavity is fliewn at AD. I then drill four
holes in it at E F G H, to correfpond with thofe marked P Q R S in
fg. 2 ; and with brafs rivets I join the two pieces together. I
then prepare another brafs fpring, as at Jig. 4, I K L M, in which
Vol. II, E c
( 218 )
I alfo make a hollow, as at K L, to embrace the glafs tube, and hav-
ing drilled two holes in it at A B, to correfpond with the two holes
Q R, in fg. 2, I place it on the contrary fide of the plate, fg 2,
and rivet it with two brafs rivets through the holes Q R.
I then prepare another piece of brafs more than twice the thick-
nefs of the former, to be fcrewed clofe to the plate, fg. 2, and to
which the microfcope is to be fixed ; this piece of brafs is repre-
fented at fg. 5, NOPQRST, and in this I drill two holes to
correfpond with thofe at O and N in fg 2 ; thefe holes, V and W,
are made to receive fci-ews in them, in order to fix by them the
plate, ^g'. 5, to the plate, fg. 2. In this piece of brafs, I alfo drill
a third hole with a fcrew fitted to it, by which the magnifier may
be adjufted at a proper diftance, which hole is fliewn at X. I
make likewife in this piece of brafs a fourth hole, rather larger than
the former, in order that the magnifier, when adjulled by the fcrew,
may be moved to the one fide or the other : lallly, I bend this piece
of brafs, at the place marked with the dotted line PR, to a right
angle.
I then make three fcrews, one of which is fhewn at A B, fg. 6,
and with two of them I fcrew the brafs, fg. 5, to the plate, fg. 2,
paffing one fcrew through the hole O, ^^g- 2, and V, fg. 5, and the
other through the holes N, fg. 2, and W, fg. 5 : the third fcrew
is to fix the magnifier by the hole Q, to the piece of brafs, fg. 5 .
I alfo make a fourth fcrew, as at fg. 7, CD ; the only ufe of
which is, that, being pafled through the hole X, in Jig. 5, it may
ferve to fix the magnifier at a proper difiance from the objed to be
viewed.
Fig. 8, E FGH T, are two thin plates of brafs or filver joined
with five rivets, between which the magnifying glafs is placed at
Iv ; and at K is fliewn a hole made to receive a fcrew, by which
the magnifier is fixed to the brafs inftrument before defcribed.
1 have alfo caufed a drawing to be made of the whole inftrument,
as viewed on one fide, (before the magnifying glafs is joined to it).
( 210 )
which is fhewn at Jig. 9, and in this figure L M N T, Ihcws that
part which, in fig. 2, is reprefented at AB F : and the round hole
in that figure is in this fhewn at a b c. In this figure alio O P Q R
is the part reprefented in fig. 2, at C D E, and the round hole, d e f ,
in this figure, is the hole K L M, \nfig. 2. The brals fpring V W X
is tliat which, \nfig. 3, is fhewn at A B C D, and the fpring AB C D,
in this figure, the fame which is fliewn, in^^. 4, at I K LM. The
piece of brafs fliewn in fig. 5, N O P Q R S T, is reprefented in this
figure at E F G, and the two fcrews, by which it is made faft, are
fliewn at Y and Z ; the brafs fcrew, in fg. 7, marked C D, is in
this figure fliewn at H, where it is feen fcrewed in its place.
I then directed the limner to make a drawing of the entire in-
flrument, with the micro fcope joined to it, and the glafs tube in-
clofed in it, the fame being adjulled ready for ufe, and fo placed
before the view ; this is fliewn at /^ 10, A B C D E F G H ; the
filver or brafs plates, inclofing the magnifying glafs, are fliewn at
I K LM ; the brafs I'crew, by which the magnifier is fixed, is fliCMai
at 2 ; the fcrew, by which the obje6l is placed at a proper diftance,
is marked at 3, and the glafs tube, containing the Eel, and fixed iu
the inllrument, is reprefented by Q R S T V W X Y.
It is my practice to ufe glafs tubes of a fize fuitable to the Eels
which are to be viewed ; and though but a fmall Eel be placed
within the tube with its head towards the bottom, yet the glafs
tube will project fo far below the inftrument, that it may be held
in the hand by that part, fo that it will not be neceflaiy to touch
the inflrument with the hand, and with the other hand the magni-
fier, which will be held next the eye, may, by means of the fcrew
at 3, be drawn out, or comprefled inwards, until the part of the
objeft to be viewed is brought to a proper difl:ance.
When I wifli to take out or put in the glafs tube, which 1 gene-
rally do at the upper end, I remove the magnifier a little on one
fide, that it may not be fcratched by the glafs tube ; this pofition
or removal is marked in the figure by the dotted line N P F.
E e 2
( 220 )
I alfo made another inftrument of like Hiape with the former, in
wliich the fpring reprefented in^^. 9, at ABCD, is a little fliortcr ;
and to this I fcrewed the brafs containing the magnifying glafs, as
reprefented in fig. 11, H I K L, on which magnitier or microfcope,
I fixed a little dith or concave reflc6lor, to throw more light on the
ohje6l ; to which intent I filed away as much as I could of the brafs
about the microfcope, as may be feen at Jig 12, MN O P, where
this is lliewn on the oppofite fide.
I have alfo given a drawing of the glafs tube containing the Eel,
which is fhewn ^tfig. 13, Q R S T V. The Eel placed in this tube,
I at firfi; ufcd to cover entirely with water, but I found that when
the tail was left out of the water it would, being wet, fprcad itfelf
on the glafs, and be more eafily viewed (this fin of the tail is Ihewn
at W) ; and I always, before putting in the Eel, wetted the infide of
the glafs, for otherwife the glutinous matter from its body would ad-
here to the dry glafs and impede the view.
I alfo recommend to thofe who make thefe experiments, as
foon as ever the Eel is taken out of the tube, to let the glafs be
well cleaned, for otherwife the glutinous matter from the fith will
dry on the glafs.
I have caufed many glafs tubes to be blown for thefe experi-
ments, but the rounder they are, and the thinner the glafs, the bet-
ter : fome of them I caufed to be made clofed at one end, as here
fhewn at Q, others I clofed with a cork.
I have alfo viewed the circulation of the blood in the tail fin of a
Perch, and that in fuch minute veflels as would only admit one glo-
bule or particle of blood to pafs through at a time.
I once faw in a large artery in a Perch, (I call it large in refped;
of the mofi; minute ones, though this was not thicker than an hair
of one's head), and which is reprefented at ^g-. 14, the blood pro-
truded from A to B, though but faintly ; from B to C, I could only
perceive a fmall agitation of the blood, and beyond C it was coagu-
lated : from this artery there arofe a branch as reprefented in the
( 221 )
figure at B E, which carried almoft all the blood from A B, through
B E, into the vein D E F, in which vein the blood was conveyed
from E to D, and all the blood which lay between E F was coa-
gulated.
When thofe Perch which I examined were very lively, and their
tails unhurt, I could not difcern the large veflels in their tail fins,
but when the blood began to coagulate, fome of the veflels, in a
fliort time, appeared fifty times larger than their natural fize. There
were other vellels in which the blood had circulated, and were not
fwelled, but here the blood was at a fland, and the veflels them-
felves, by reafon of their minvitenefs and there being no circulation,
in them, were not eafily difcerned.
Moreover, it was my opinion that many of the large circulations
of the blood, which I faw, when it began to flagnate, were not
performed within the coats of the blood- vellels, but that, when the
blood in the arteries was impeded in its courfe, the continued and
ftrong propulfion from the heart caufed it to form new canals, where
the fifli's fkin made the leafl refiftance, and that it was by this
means the oblique current of blood, fliewn in Jig. 14, at EB, was
formed. And, indeed, I am of opinion that all thofe very minute
currents, whether we call them arteries or veins, are not performed
within the coats of veflels, but that they are formed where the blood,
in its protrufion from the heart, meets the leafl refinance. But if
we fuppofe one of the very fmallefl blood-veffels to be provided with
a coat, and fuch coat to confift of three ditlinft membranes, as it is
faid the coats of the veins and arteries are formed, it neceffarily fol-
lows that the coats of thofe minuteft vefTels muft be of a thinnefs
which is inconceivable. For, let us fuppofe, as I have often faid,
that the axis of an hundred globules of the blood, from whence its
rednefs proceeds, are no more than equal to the axis or diameter of
a large grain of fand; it follows, that ten thoufand globules of blood
may pafs together through a veflel, no larger than to admit a large
grain of fand to pafs through it. Now, fuppofing the coat of fuch
( 222 )
a vefTel, as will admit a grain of fand to pafs through it, is twenty-
live times thinner than fine poll paper, how much thinner mull be
the coat of a vein which will only admit the ten thoufandth part of
a grain of fand to pafs through it ? Therefore, if thefe very fmallert
blood-vclfels are provided with coats, fuch coats mull be fo thin,
open, or fpongy, that the very thinnell watery parts of the blood
can as eafily pafs through them as water through a fine fieve.
After this, I took one of thofe fifli called a Jack, which I placed
fo that about the breadth of a finger of its tail was above the water,
and, upon examining the extremities of this tail fin b}' the micro-
fco])e, I could not perceive the leall motion in the blood in that
part ; \\ hence I judged that thofe parts of the tail were mortified,
for the filh, from its appearance, feemed to me to have been caught
fome da}'s. But when I examined the tail fin, nearer to the body,
I fiiw the blood llowly moving in an artery, and, a little nearer to
the body, there ilfued from this artery a fmall branch, through vvhich
the blood was carried with a very fwift current, and this branch,
taking a fmall bending, carried the blood into a vein which brought it
back towards the heart. Let G H I, in Jig. 15, rep relent this artery,
in vA'hich the blood from G to H was driven forward with its ufual
fwiftnefs, and from H to I its motion was very flow ; H K M, is a
fmaller vellel, through which the blood was carried from this artery
into the vein L M N, at the point N, and in that vein conveyed
back to the heart.
After this, 1 bought a parcel of Trout, which had been caught in
the river Maes two or three days before, and among the reft was
one, not quite ieyen inches long, which, upon view of its fcales, I
judged to be be about five years old. This Trout, whofe tail fin was
a little injured at the extremity, I placed with its tail about a finger's
breadth: above llie water; and, when it was become quiet, I viewed
the tail by the microfcope, and I could not difcover any circulation
at the extremity, but, examining it a little nearer to the body, I faw
the blood in the arteries and veins ftagnating and coagulated ; and I
( 223 )
alio perceived the arteries to be uncommonly large, which I con-
ceived to proceed only from this, that the circulation being impeded,
they vs^ere by the impulfe of the blood diftended to that lize.
Upon viewing the fin ftill nearer to the tail I fav^^ the blood run-
ning both in the arteries and veins, and what teemed to me very
worthy of note was this : I favv the blood llagnating in an artery,
fliewn in p'g. 1 0, at O F Q, from P to Q, and fo on towards the
extremity of the tail, and in the fame artery from P to O, and alfo
towards the fifli's body, the blood was carried in its ufual motion,
namely, from O towards P. From this artery there arole a branch,
reprefented at P, in which the arterial blood, after it had been driven
thus far, was carried back towards the heart, fo that this branch,
PV, arifmg out of the artery, OPQ, muft be called a vein.
At about three hairs breadth from the before mentioned artery,
there was another artery, nearl}^ of the fame fize, which is Ihewn in
the figure, at R S T. In this the blood between S and T, and alfo
beyond it, was coagulated, and the blood which, from R to S, was
driven forward, iflued into a branch arifing out of that artery, at S,
which alfo led back towards the heart, as is lliewn in S V ; \\ here,
at V, both the veins, P V and S V, are joined, and conllitute a larger
vein, VW.
Moreover, I took a Carp, in order to view the circulation, but it
was fo reftlefs that, after many trials, I determined to wrap it in a
cloth, in order to view the fin on its back, which, being nearer to
the heart, I judged the circulation might be llronger : and here 1 faw
the blood moving in an artery, which divided itfelf into two other
arteries, fo fmall as orily to admit a fingle globule or particle of
blood at a time ; one of thefe minute arteries was joined to a Acin, fo
large that the blood in it began to aflume a red colour, the other I
could not follow with my eye, becaufe its courfe was hid behind a
fmall bone in the fin. Fig. 17, AB, is this fmall artery, which, at
B, was divided into two branches, one of which, B C, was joined
to the vein D C E, at C ; fo that the blood whichj in the artery, was
( 224 )
driven from A to B, from the heart, and took its courfe from B to
C, in C, being emptied into a vein, it returned back, from C to
D, tovi^ards the heart: the other fmall artery, B F, took a courfe out
of my fight at F. This circulation gradually decreafed till, at length,
I could not perceive any motion in the veflds ABC and B F.
Thefe obfervations I alfo purfued in feveral other forts of fifh, and
in all of them the circulation was very apparent, particularly the
Flounder, in the tail fin of which I faw fuch multitudes of minute
blood-veflels, that I may fay there is not a fpace in that fin, fo fmall
as a grain of fand, which does not contain a veflel, either conveying
the blood from the heart, or bringing it back towards the heart.
This fifli, called the Flounder, is one of the beft adapted to view the
circulation of the blood, becaufe it lies quiet a long time, and alfo
\\ ill live a long time out of the water.
With regard to the infiruments I have defcribed, they might, I
doubt not, be made more perfect and convenient ; for I myfelf was
never infi:ru6led in the working in brafs and iron, otherwife than by
obfervation of workmen in the making and ufing their tools ; by
which means, however, I have been enabled (rather in a rude way)
to make thefe infiruments fufiicient to anfwer all my purpofes.
Addition, by the Translator.
AS the reader may have a defire to know of what nature were the Mi-
•crofcopes by which Mr. Leeuwenhoek made the wonderfal difcoveries, wliicli
are the fubjeft of his works, the Trandator has thought proper to introduce,
in this place, the bed account of them he has been able to colIeO.
Mr. Henry Baker, in his IntroduQion to the ufeof the Microfcope, has
thefe words : *
" The famous Microfcopes of Mr. Leeuwenhoek are the mofl fimple pof-
" fible, being only a fmgle lens fct between two plates of filver, perforated
*' with a fmall hole, with a moveable pin before it to place the objed on, and
• Wicrofcopc made Eafy, p. 7. aud 8. Ed. 1711.
( 225 )
*' adjuft it to the eye of the beholder. Several writers reprefent the glafles
" Mr. Leeuwenhoek made ufe' of in his Microfcopes to be Tittle globules,
" or fpheres of glafs ; which miftake moll probably arifes from their under-
" taking to defcribe what they had never feen ; for, at the time I am writing
" this, the cabinet of Microfcopes left by that famous man, at his death, to
" the Royal Society as a Legacy is (landing upon my table; and I can alTure
" the world that every one of the twenty-fix Microfcopes, contained thereiuj
" is a double convex lens, and not a fphere or globule."
And in another treatife, publifhed by Mr. Baker fome years afterwards,
he writes as follows : *
" An accurate defcription of the twenty-fix Microfcopes, and objects be-
" longing to them, contained in a fmall cabinet, which Mr. Leeuwenhoek*
" at his deeeafe, bequeathed to the Royal Society, was prefented many years
" ago to that Society by Martin Folkes, Efq. and may be feen No. 380 of
" the Philofophical Tranfaflions. And a farther account, fetting forth the
" magnifying powers and other particulars concernmg the faid Microfcopes
" (which were three months under my examination for that purpofe), was
" prefented by me to the Royal Society in the year 1740, and publifhed in
•' Phil, Tranf. No. 458. But neither of thefe accounts has any drawing of the
" Microfcopes : it is therefore hoped the curious will be pleafed to fee a draw-
" ing of them, taken, with great exaftnefs, from thofe in the Repofitory of
*' the Royal Society, which are all alike in form, and differ very little in fize
" from this drawing, or from one another.
" The two fides of one of thefe Microfcopes are fhewn at^^. 18 and IQ:
" the eye mud he applied to the fide Jig. 18. The liat part. A, is compofed
" of two thin filver plates, faftened together by little rivets b, b, b, b, b, b.
" Between thefe plates a very fmall double convex glafs (called by mathema •
*' ticians a lens) is let into a focket, and a hole drilled in each plate, for the
" eye to look through, at c. A limb of filver, d, is faflened to the plates
" on this fide by a fcrew, e, which goes through them both. Another
" part of this limb, joined to it at right angles, paiTes under the plates, and
" comes out on the other fide (fee^°-. ig) at f ; through this runs, dircQly
" upwards, a long fine-threaded fcrew, g, v.hich turns in, and raises or lowers
" the flage, h, whereon a coarfe rugged pin, i, for the objeft to be fallened to,
♦' is turned about by a little handle, k, and this ilagc, with the pin upon it,
• Employment for the Microfcopc, p. 13J. £d. 17G4.
Vol. II. F t^
( 22(5 )
" is removed farther from the magnifying lens, or admitted nearer to it, by
" a little fcrew, I, that, paflTmg through the flage horizontally, and bearing
" againft the back of the inftrument, thrufts it farther off when there is oc-
" cafion. The end of the long fcrew, g, comes out through the ftage, at m,
" where it turns round, but afts not there as a fcrew, having no threads that
" reach fo high. Thefe Microfcopes are plain and fimple in their contrivance : ,
" all the parts are filver, fafhioned by M. Leeuwenhoek's own hand, and the
" glafTes, which are excellent, were all ground and fet by himfelf.
" The magnifying powers of thefe glafles come fhort of fome now made,
" but are fully fufficient for mod purpofes. Of the twenty-fix Microfcopes
" I examined, one magnifies the diameter of an objeQ; l6o, one 133, one
" 114, three 100, three 89, eight 60, two 72, three 66, two 57, one 53>
" and one 40 times,"
♦
On Frogs, and the manner in which their young are produced from
Tadpoles, tvith the circulation of the blood Jeen in them : alfo
on thefliape of the component particles of the blood.
W E have two forts of Frogs in this country, one which ufed to
be found in great numbers about the town of Delft, but of late
years only few of them have been feen, by reafon, as I believe,
that their fpawn has been devoured by a fmall kind of filh ; and I
have fometimes feen this (pawn in the fmall ditches which divide
our fields, lying in fuch quantities, that the furface of the water
feemed almoft covered with it. The other fpecies of Frogs is much
fewer in number, but of a larger fize, and they leap farther than
the others, and the hind parts of their bodies, or rather the thickefl
parts of their legs, are ufed by the French, as good food. Refpe6l-
ing the propagation of thefe laft, as a particular fpecies, I was for
fome time in doubt, not having obferved them couple together, nor
feen any of their eggs or fpawn.
But one day, at the end of the month of May, walking in a mea-
dow for my recreation, and not thinking of this fubjedl, becaufe the
time of the other fort of Frogs laying their eggs was long pall, my
attention was excited by the noife or croaking, which thefe iall
mentioned Frogs make both by day and night, in hot weather,
whereupon I went to the fide of the water, and I thought that I
faw fome of their eggs adhering to a green leaf in the water, and i'o
in fa6l it proved. Thefe eggs are not fo ealily to be difcerned, as
thofe of the common Frogs, becaufe the glutinous matter or jelly
which contains them, fwims deeper in the water, and is alfo lefs
in quantity,
Ff 2
( 228 )
I caufed fome of the leaves, to which thefe eggs or fpawn adhered,
to be brought to my houfe, and put them into two earthen veffels
filled with the water that runs through our canals ; and then I ex-
amined thofe eggs by the microfcope, and found that, for the moft
part, they were dark coloured on one fide, and yellow on the other :
but looking at them again the next morning, I found that the yel-
low colour was almofl vanifhed, only a fmall part of each egg re-
maining of that tinge, whence I concluded that the eggs had been
but lately laid by the Frog when I took them up.
Moreover, I took feveral eggs out of the tranfparent glutinous
matter or jelly, which contained them, and I found this glutinous
fubflance, by which the eggs feemed to be preferred difiin(5t in
their round fliape, to be very flrong and tough, fo that it could not
be feparated from the egg itfelf, without being torn ; and when I
handled it ever fo gently, the egg did not retain its round figure,
but broke to pieces. I examined many of the eggs after I had taken
them out of the jelly which inclofed them, and found them to be
contained in a very thin membrane, formed with black parts or
fpots, in fliape agreeing with the knobs or protuberances in that
leather which is called fhagreen.
The egg itfelf, as far as I could difcern, confifted of a watery
matter, (as it appeared to the fight) and an incredible number of
globules, each of which again confifled of a great number of lefTer
globules, all having a larger globule in the middle ; fo that every
one of them had the appearance of an egg with a very fmall yolk.
The figure of many of thefe eggs altered every day; for, from
being round, they aflumed an oblong fhape ; afterwards minute tails
were formed ; and I alfo thought that I faw the appearance of
heads.
Every day I opened feveral of thefe eggs, and until the feventh
day after they had been brought to my houfe, when I faw the
young Frogs (which are called Tadpoles) to be fo far formed, that
they began to move. But, with all my attention, I could perceive
( 229 )
nothing in them except globules ; and upon opening a Tadpole,
which of itfelf crept out of the jelly which had contained it, and
was fwiniming in the M^ater, and in which, when it was entire, I
could diftinguifli the back bone, I could not, when diflected, dif-
eover any bowels, much lefs arteries or mufcles.
Hereupon it feemed to me, that the whole body of this animal,
called a Tadpole, conlifted of no other particles than globules, and
efpecially the belly of it, which was of a yellowilh colour, and
feemed to be made of that part of the egg which had continued
yellow. This feemed ftrange to me, that in fo large an animal
which I had killed and dilfedled, I could not difcover any veflels or
fibres.
After all my obfei-vations refpecfting thefe eggs, I could draw no
other conclufion, than that the glutinous matter or jelly, encom-
paiTmg the eggs, was only formed by nature for the prefervation of
the egg when depotited in it, as the Ihells of birds' eggs cover and
protect the whites and yolks.
And as we fee, that the whole fubftance of a hen's egg paHes
into and becomes part of the chick, (except the fliell and the mem-
brane within it, which are deligned for the prefei-vation of that fub-
llance), fo in the prefent cafe, the whole of the egg pafles into the
body of the Frog or Tadpole, and the vifcous and gluey matter, which
furrounded the egg, remains after the young has left it. So that
we may fay of the eggs of Frogs, what I have faid of the eggs of
birds, namely, that they are deligned to fupport and nourifh the
young creature until it is able to provide for itfelf
When I obferved that the vifcous matter or jelly I have men-
tioned, contained in it multitudes of air bubbles, I concluded the
ufe of them was, that where there were no leaves floating on the
furface of the water to which the eggs could adhere, thefe air bub-
bles might make the jelly float on the water, whereby the eggs might
receive the warmth of the fun, and thereby, as I may fay, be
hatched.
- ( 230 )
Plate XVII. fg. 20, rep relents the egg of the Frog I am now
defcribing, incloled in the tenacious or vifcid fubftance I have
mentioned ; and when it is lb far grown, that the animal begins to
move, the tail appears fome\\hat bent. Fig. 21, reprefents the
animal, when fo fully formed in the egg, as to be able to fwim
in the water ; this was taken by me out of the egg, and laid on a
glafs, where it died, and the body of it dried up.
Fig. 22, A B C D E F, reprefents the fame animal as it appeared
to the limner through the microfcope, in which the head can
ealily be diftinguilhed from the fore part of the body, as is repre-
fented at A B F.
FE is the belly of the animal, which was of a yellowilh colour,
being formed, as I have laid, out of that part of the egg, where
there remained a yellow fpot ; but this drawing is not exacftly like
the animal, becaufe it was fo broken and torn, that it only exhibited
the appearance of globules.
C 1) E reprefents the tail of the animal, in which a fpine or back
bone could very plainly be diliinguifhed, and is here rcprefented in
the figure in the beft manner the limner was able; and though I
opened many of the tails of thofe animals, which had this appear-
ance of a fpine, I could not difcover in them any other parts than
globules.
Thele little animals, or Tadpoles, in fwimming, move their tails
with great force, and as foon as they ceafe the motion, they link
to the bottom of the water, whence it appears that their bodies are
fpecifically heavier than water. But thefe animals have a property
(while in their Tadpole Hate) to fix their heads to the glafs, fo that
they are able to faftcn themfelves to any thing they find in the wa-
ters, and there to remain without finking to the bottom.
Moreover, I placed a Tadpole, which was alive in the water and
liad fixed itfelf to the glafs, before a microfcope, direding the limner
to make a drawing of it as it appeared to him.
F/^. 23, G H I K L M N O P Q R S, reprefents this Tadpole alive,
( ^31 ^
as it had fixed itfelf to the glafs, with its belly next the eye of the
fpeAator ; this Tadpole had but a few hours before quitted the egg
and jelly in which it had been inclofed.
L M NOP, reprefents the head ; H IRS, the belly ; and G H S,
the tail. In the upper part of the head of this animal, its Ikin ap-
peared fomewhat thicker than the reft ; fo that I concluded, this was
a part of the Ikin which in time would cover the whole body of the
animal : this is reprefented at M NO. The mouth is ihewn atT,
which I did not perceive this newly hatched animal to move. At
V V are two dark fpots in the animal's head, of a veiy round Ihape,
and being much more protuberant than I have feen in any other ani-
mal, and which many would conclude to be the eyes. But if eyes,,
they would not be feen by us in this pofition of the animal ; but ra-
ther be placed on the otlier fide out of fight.
I K L, and P Q R, are fix tranfparent parts hanging down from
the head, three on each fide, and thefe parts were the only reafon
of my giving a drawing of this Tadpole ; for in each of them I, with
great delight, faw moflidifiindly the circulation of the blood, which
was driven from the parts next the body to the extremities, and
there, with great fvviftnefs, performed an incefiant circuit back to the
body. This circulation had not an equable or even motion, but
was performed at intervals by quick repeated protrufions ; and in the
intervals, any one for the moment, would have thought the circu-
lation cealed ; but fcarcely had the current of the blood begun to
make a fl;op, when a new protrufion immediately followed, caufing
a continual courfe of the blood in this creature; and, upon accurately
computing the time in which their pulfations or protrufions were per-
formed, I may fay, that an hundred of them \^ ere performed in lefs
time than one could count an hundred. From thefe appearances, I
concluded that at every one of thofe protrufions, the blood was
driven out of the heart, and I could perceive this motion (namely,
the protrufion of the blood from the heart, and its paflage from the
( 232 )
arteries into the veins, where they are united), as diflin^lly as any
perfoii can polTibly imagine.
"When thefe Tadpoles were fomedays old, thofe dependent parts,
wherein the circulation of blood I have defcribed was performed,
were no longer to be ieen, being, as it fcemed to me, grown over by
the animal's Ikin. Isut I even then faw fomething of a rapid mo-
tion, as before defcribed, performed on each fide the head, though
I could not diftinguilh it to be the circulation of the blood ; at the
fame time, the head became fo conjoined to the body, that it
could not be dillinguiflied from it.
The circulation of the blood, as seen in the tail of the Tadpole,
has been noticed in another place,* therefore no more need be added
here, than that my obfervations on this creature were not made upon
a fnigle infpection of the fubject ; but I often repeated the fame, on
account of the pleafure I took in the fight, and in different Tadpoles,
but I always found the appearance to be the fame. And one thing
is here worthy of not^, that in the very fmall veflels at the greateft
dhhmce from the heart, as in the extremity of the tail, there did not
appear fuch a foi'cible and vehement protrufion as in the veflels near
the heart ; but though the blood in thofe fmall veflels appeared to
move in an uninterrupted courfe, yet it could plainly be feon, that
at every pulfation of the heart the courfe was a little accelerated.
I have in another place faid, that the particles or globules of blood,
from whence its rednefs proceeds, are fo minute that a million of
them taken together would not equal the fize of a large grain of land,
and from hence we may eafily conclude how exceffively fmall mult
be the vellels in which this circulation is performed.
As many perfons have never feen a Tadpole, I have caufed a draw-
ing to be made of this creature, which, defpifed as it is, has afforded
me the greateft pleafure ; for the circulation of the blood, in this
animal, is more admirable to behold than in any other creature or
filh I ever faw : and luch has been my delight in viewing it, that
* Vol. I. p. 92.
( 233 )
I thinlc no fountain whatfoever, either natural or artificial, or indeed
any other fpedlacle, could have afforded me fuch plealure as thele
fniall animals.
Fig. 24, repreferrts a Tadpole, when grown to fuch a fize that
both its hind feet were formed, and it could ufe them; the two fore
feet were alfo vifible, but as yet lay hid under the Ikin.
jSIoreover, I examined the Tadpoles when they were fo far per-
fected as to become Frogs and leap about the fields, and in thefe I
alfo difcovered a great number of wonderfully minute blood- vellels,
which with their bendings conllituted thofe vellels we call arteries
and veins; fo that it moft manifeilly appeared to me that the
arteries and veins are only a prolongation of one and the fiime
veliel. And this was moll; particularly manifelt in the extremity
of thofe parts in the foot, which may be called the fingers, and of
which the Frog has four in each of the fore feet and five in the
hind feet.
Thefe blood veflels, which we call veins and arteries (though in
fact they are one and the fame), were to be feen in great numbers
at the extremities of thofe fingers, and each of them had a round
bending, fo that the dillincl courfe of each of them could not indi-
vidually be difcovered. All thefe veflels were fo fmall and thin that
they only admitted the paflage of the blood in fingle globules. But
when I examined them at the firll or fecond joint of the fingers,
then I faw the arteries and veins were larger, fo that the blood in
them was of a red colour.
I did not only examine thefe young Frogs in parts of their bodies
only, but placed their whole bodies before the microfcope, and the
before mentioned blood-velfels appeared to me as I have already de-
fcribcd them. This circulation I fhewed to two refpedable gen-
tlemen, who could not behold the fight without great admiration,
efpecially in thofe places where they faw the blood running in fuch
fmall vellels as to be only pervious to one of thofe particles, \^•hence
its rednefs proceeds.
Vol. II. G g
( 234 )
I alfb examined larger Frogs, and in their feet I law the circula-
tion of the blood, but with much difficulty, and, unlefs I had be-
fore difcovered it in the fmall ones, it would have been impoffible
for me to difcover the complete circulation in the fmallest vellels.
But when I examined other parts of the bodies of thefe larger Frogs,
I there completely dilcovered the circulation.
Among other things, I at one time faw the blood in an artery
(large enough to admit three globules of blood at a time) driven in
a contrary direction to the ordinary one; but this retrograde motion
lafted no longer than while one could tell four, after which it re-
fumcd its ufual courfe. To illullrate this : I faw the blood running
as defcribed in fig. 25, N R O P, palling from N to O ; out of which
artery arofe a branch or fmall artery ; but here the light which at-
tracted my notice was, that the blood in the artery, P Q, not only
fuddenly flopped in its motion, but was driven back from Q to P, and
emptied into the artery N R O P. The caufe of this, I think, might
be, that the blood in the fmall artery, P Q, or in the fmaller branches
into which the artery, P Q, was divided, had met with fome fmall
obftruftion, or that fome mufcle, adjoining to thefe fmall vellels,
fo prelled upon them, that the courfe of the blood was thereby im-
peded, whence the blood was not only llopped in its progress, but
driven by a backward motion into the artery adjoining ; for, after
the lliort time I have mentioned, the blood relumed its motion in
the fame courfe and with the fame fwiftnefs as before.
In another place I faw the courfe of the blood, in the fame kind
of artery, very much retarded for a fliort fpace, and immediately
afterwards in the fame artery a fudden protrulion, and diredlly after-
wards another Hop or lliort interruption in the circulation. This pro-
trufion and interruption took place live or fix times fuccelTively, af-
ter which followed a fwift and regular motion, and all this was per-
formed in fo lliort a fpace of time, that I could fcarcely have fpoken
ten words in the interval.
( 235 )
In my feveral obfen/ations on the circulation of the blood in tiflies
I have not been able clearly to latisfy myfelf with regard to the
fliape of the globules or component particles of the blood, for they
fomctimes appeared of a fpherical, and fometimes of an oval and
even a flat lliape, and fometimes an irregular figure ; this I fome-
times attributed to my glafles not being of fufficient magnifying
power to dilHnguifh them, and fometimes- to the pofltion in which
they appeared to the eye, for, while in circulation, they tumbled one
over another, fometimes prefenting one part and fometimes another
to the view; and I alfo thought that it might be owing to the llrait-
nefs of the vefl^els, in which the particles of blood, being of a yield-
ing nature, might, by the comprelFion, lofe their fpherical figure.
In order to fatisfy myfelf in fome degree on this head, I cut olT
pieces from the tails of feveral fmall flat fifli, fuch as Plaice and
Flounders, in order to view the blood when drawn out of the vefl^els,
and the rather, becaufe I could not perfuade myfelf, that the na-
tural fliape of the particles of blood in fifties was an oval ; foraf-
much, as a fpherical feemed to me to be the more perfe6l form.
For I was of opinion, that the particles of blood in fifties were coni-
pofed of fix globules, in like manner with the blood in man, and in
terreftrial animals : and I feveral times faw the particles of fifties
blood, the original texture of which was broken, and in which I
could difl:in6lly fee four or five, and in fome few of them fix com-
ponent particles. I, however, thought it worthy of note, that many
of thefe particles of blood appeared to me of an oval fliape, fome
few others roundilh, and others of a perfe6l fpherical figure.
In order farther to profecute my inquiries on this fubjeft, I took
the blood of a Salmon not quite dead, which was received into a
glafs tube, about the fize of a fmall writing pen : this blood, after a
fliort time, became coagulated ; but having reftored it in part to its
fluidity, I put it into a fmaller glafs tube, in which I viewed it, hold-
ing it fo, that the particles of blood might be kept in motion con-
tinually, by which means many of the particles appeared before my
Gg2
( 236 )
fight with a flat and oval fliape ; in others, the fides of which were
turned towards me, I could fcarcely perceive any fenfiblc thick-
nefs ; and in lliort, others, where their fides were not exadly turned
tov\ ards me, appeared Ibmewhat broader in proportion to their fize ;
but I could not dilcover one particle of blood of a perfe6l Ijpherical
Ihape.
The blood of a Salmon appears, to the eye, of a blackifli colour,
by reafon of the very great number of thofe particles which give the
blood its red colour, and which are more in number in this filh's
blood than in others.
Moreover, I fpread a fmall portion of tliis blood upon a clean thin
glafs, and 1 obferved where the particles of the blood lay thin-
ncli, that they were of oval fliapes, and in many of thofe oval par-
ticles, it could be feen that they were compofed of globules ; and
I law a few of them, wherein I could dillinguilh fix globules lying
in two rows, three and three.
But where the particles of blood lay in numbers clofe together,
they were fo coagulated, that no oval figures could be feen in
them, and all I could obferve was fome confufed particles, fix of
which made up one entire particle of blood.
Thefe renewed inquiries of mine were, with intent to difcover
whether I had before been in an error, by faying, that the parti-
cles of blood in fiihes, were not oval, but fpherical ; becaufe all
thofe perfons who had feen the circulation of the blood at my
houfe, were of opinion, that the particles were not oval, but
fpherical.
I have heretofore faid, and do fi:ill believe, that the blood-veflcls
in many parts where I have viewed the circulation, are fo extremely
flender, that if a large grain of fand was divided into a million of
parts, not one of thofe parts could pafs through thofe fmall blood-
veflels, \mlefs they were as foft and flexible as the particles of
blood.
I have iifed all the diligence in my power, in order, if poflible,
( 237 )
to difcover thefe oval particles at the time the blood was in its na-
tural courfe in the veins ; for which purpofe, I feledled for exami-
nation, the very fmalleft blood-veffels ; but though I was very atten-
tive, I could not fatisty myfelf, for fometimes I faw a darkifh parti-
cle, then one much more tranfparent ; and when I viewed the very
fmallell veflels, in which the blood had little or no motion, as
divers veflels at the extremity of the fins, the particles of the blood
lay fo very thin and fcattered, that I could not fee any thing ex-
cept a liquid without a motion, which was fomewhat of a yellow
colour.
I have heretofore caufed drawings to be made of the particles of
blood, reprefenting them of an * oval fliape, though the limner had
not the originals before him. I have alfo dikited blood with water,
becaufe the multitude of its particles impeded a just view of them ;
but now, for the greater fatisfadlion of myfelf and others, I gave
into the hands of the limner a microfcope, before which was placed
a portion of the blood of a Salmon, in order that he might make a
drawing of the particles as they appeared to him.
Fig. 20, AE CD, fliews the oval particles of the blood of a Sal-
mon, which weighed about thirty pounds.
At A B are reprefented thofe particles which did not come in a
ftraight line before my eye ; the others, fliewn at C, floated llraight
before the fight : in mofl: of them was a luminous fpot, though in
fome larger than in others ; thefe the limner alfo obferved, and
reprefented them as nearly as he could in the middle of the parti-
cles in the drawing. Thefe particles appeared black, and I dilpofed
the ferum in which they floated, in fuch a manner as to make
them fink to the bottom, though with fome difficulty ; and in this
pofition the limner had an opportunity of feeing fome thoufands of
thofe particles.
* See Vol I. p. 9-1.
( 238 )
H I had made a drawing of thefe particles, as they appeared to
me, I lliould have reprelented them twice the lize here Ihewn,
fo that here is an inllance of the diverdty of fight in different
people.
Moreover, I placed before a microfcope the blood of a fniall
Flounder, Jiot diluted with any other liquor, but tlic particles were
floating in their own proper ferum ; thel'e particles are fliewn at
Jig. 27, between E and F.
Although thefe particles are reprefented fomewhat fmaller than
the former ones, I could not perceive any difference in their lize,
and I am certain, that there is not fuch difference, but that the par-
ticles of blood, whence its rednefs proceeds, are no larger in a
whale than in the fmallell fi(h.
I alfo put fome particles of the blood of a fmall Flounder in a
clear and very" clean glafs, and placed them before a microfcope of
lefs magnifying powers than the former, in order that I might Ihew
them, even in the dark days of winter, by day-light alone. Thefe
particles of blood, in the middle of which the light could be feen,
and which was obfei'vcd by the limner, are llicw-n at fig. 23, be-
tween G and H.
I had alfo fome blood lying in a glafs before deeper magnifiers :
from thefe the thin ferous liquor was evaporated, and in fome few
of thefe oval parts (which were fo feparated, that they did not
touch one another), it could be feen that each of them, as far
as the eye could ditlinguifli, confilled of fix globules : thefe fix glo-
bules the limner imitated as near as he could, as appears at^o-. 2y,
between I and K.
After thefe obfervations, I devifed means to view the circulation
of the blood through deeper magnifiers than what I had ufed be-
fore, in which attempt I fucceeded fo as to fee the rapid courfe of
thefe oval particles in the blood- veffels, by feveral different microf-
copes, and the greater the magnifier, the plainer was the courfe of
( 239 )
blood to be feen : in order to abate this rapid motion, 1 Ibmetiraes
preiTed the fmall arteries for the fpace of two minutes, when I faw
in divers fmall blood-veflels, fome oval fliaped particles were fo fe-
parated from each other, that in fuch veflels no particles of blood
could be diftinguiflied, not even thofe of which fix go to make up
one entire particle of blood, but only a fluid fubftance palfing
through the veflels, which was almoft colourlefs, and in one of the
large blood-veflels in the tail, which was an artery, the blood ran
very flowly : in this laft veflel I plainly faw that the particles
of blood in it were oval, and I not only faw them plainly, but I
could, more dillin6lly than before, obferve the component glo-
bules, of which all, or the greater part, of thefe oval particles were
compofed.
It is eafy to conceive how fix globules of a yielding or flexible na*-
ture, in continual motion and flriking againlt each other, may form
a perfedl fpherical figure, as I have elfewhere obferved : for exam-
ple, let Jis^. 30, reprefent the original compofition of a particle of
blood, confifting of fix globules, five of which appear to the eye,
and the fixth is out of fight. I have myfelf with wax made up fuch
a globule, confifling of fix fmaller ones, as is piftured ^tfig. 3o and
31, and each of thofe fix, of fix others in order to expofe to the
view of the curious, the make of thefe globules of blood ; for I may
lay it down as a fad, that each globule of our blood confifts at leaft
of thirty-fix globules ; thefe before mentioned globules, prefled to-
gether, in conftant motion, and flexible in their nature, are, as it
were, mutually compaded together, and aflume a perfed fpherical
fliape, as fliewn at fig. 3 1 .
From this difpofition of the parts, we may conceive how the
globules of blood, in men and animals, have a round figure, but
how thofe oval particles of blood I have been treating of are
compounded, and made up of fix globules, is not eafy to com-
prehend.
( 210 )
I hare before faid, that I believed every globule in our blood,
I mean thofe, fix of which go to make up a perfect globule, as is
iliewn in Jig. 30, is itlelf eompofed of fix globules, and who
knows how this is performed ? For in how fmall parts foever we,
in imagination, divide a globule of blood, there may, neverthclefs,
be particles of which fuch a globule confills, infinitely fmaller, and
I w^onder that any will be fo bold as to publilh what they do, rc-
fped:ing the original particles of matter ; for my part, I think, that
could I divide, even in imagination, a globule of blood into a thou-
fand million of fmaller particles,* 1 fliould not go the extent of its
component parts.
Since we now fee, as before is obferved, that the particles of
blood can, by preflure, be divided, and fo united with the thin li-
quor in which they float, that we take it for a fimple or uncom-
pounded liquid, we may imagine, than when a horl'e prell'es his
breall with a heavy load, the globules of blood in the veU'els, where
the prelTure is greatell, may be dillblved or divided in the velTels,
and united with the fluid, which phyficians call the ferum.
I have alfo thought, whether or no the particles of blood, fo di-
vided or diflblved, may not, when removed from the incumbent
preflure, afliime their prilHne figure, in like manner with the parti-
cles of fat or tallow ; for, if a portion of ox's or fheep's tallow is
expofed to the fire, the particles of fat, which we call globules, as
having the neareft refemblance to that fliape, are diflblved and ex-
hibit only a clear tranfjjarent liquid, even to the microfcope, but
"when the heat ceafes it again appears in the fliape of globules, and
if melted ten times over it ftill, when cold, aflumes the fliape of
fpherical particles.
I have likewife laid it down, as my opinion, that no blood, Mdiich
is carried in a vein to the heart, can become arterial blood, unlefs
* The Latin tranflation has i( decern millics^ tea thoufand : but the author's own words
are, dinifent millioenen^ a thoufand millions.
( 211 )
it has firft pafled into the heart ; but fince, in one of the obferva-
tions I was making only for my amufement I faw the contrary, I
have caufed a drawing to be made of that appearance, in which
drawing I direAed the blood-veflels to be reprelentcd rather larger
than they appeared to me, and in the middle of the fmall veirds there
are no dots : thofe dots, in other parts of the figure, denote the
globules of blood, in order more plainly to defcribe the circulation.
Let us fuppofe A B, in.,fig- 32, to be a vein in which, by the mi-
crofcope, the blood may be feen di-iven with great fwiftnefs from
B to A. From this blood-veiiel iflued two fmall branches, repre-
fented at the letters C and D, which were united between the let-
ters E and F.
On the other hand, the letters II I exhibit an artery through which
the blood was, with like fwiftnefs, driven from H to I, and from
this artery, H I, proceeded a branch, fliewn at the letters K F L.
Now the blood running from K towards F is united to the velTel
F at that letter, and by this means the blood illuing out of the
artery is in part infufed into a vein and carried from F to G ; and
the fame quantity of blood (as according to my moll accurate
obfervations appeared) as was carried from K F to G downwards, fo
much blood of that, which was carried from C E to F, was carried
upwards from F to L ; fo that as much of the arterial blood as the
velfcl, KF, conveyed into the veflel, FG, fo much of the venal
blood did the velfel, C E, convey into the veflel, F L. And, though
I have often enjoyed great pleafure in viewing the circulation of the
blood, this fpeclacle, which I have been juft defcribing, was more
delightful than any other, becaufe I could moft clearly and ditlindly
fee the objeds I have defcribed, and alfo, becaufe I never before faw
fuch a conjundion or communication between the blood- veflels.
^Vi^
^^^^^ - .fr^
Vol. XL H h
Oxv PHOSPHORUS.*
A. CERTAIN German gentleman, who faid he was a Dodor of
Phyfic, and newly come from England, paying me a vifit, with
the compliments of feveral of my friends in London, after fitting
with me sometime, produced a fmall veflel filled with water, at the
bottom of which lay fomc fmall pieces of a whitifli fubftance, in-
clining to a tinge of yellow ; thefe he took out of the water, and
with one of them he traced upon paper fome letters about the fize
of a joint of one's finger ; and though at firtl, nothing of thefe let-
ters was to be feen on the paper, yet upon removing it into a dark
place, the paper feemed to be on fire in every place where the let-
ters had been traced : but this fire was very pale or faint, and fe-
veral hours afterwards viewing the paper in the dark, the letters
-had Hill a lucid appearance. He alfo took a fmall piece of this
fubllance and put it between two pieces of whited brown paper^
and rubbing them brilkly fix or eight times with his cane, in the
place where the before mentioned fubfi:ance lay, to my great fur-
prize, I faw the paper, by means of the fri6lion, burfi: into a flame.
This medical gentleman told me, that this fubftance was pre-
pared by difiillation from urine which had been long kept, and that
it could not be preferved, unlefs kept under water : he gave me a
piece of it, and with a particle thereof, about the fize of a pin's
head, I repeated the before-mentioned experiments three feveral'
* Mr. Lceuwenhoek calls this fubftanre ligt der nature, which the Latin Trandalor
Tenders licmen naturale, in Englifli, natural light : from the dcfcription here g'lTCn, it can. be
no other than the Thofphorus of the fliops.
( 243 )
times, not only with the fame event, but I alfo found, that when
the letters had been fo traced, and tiie paper was brought fo near
the fire as to warm it, the places where the letters had been traced,
were immediately inflamed, and the flame fpread farther over the
paper.
Soon after this, a friend of mine, who was on his travels, fent
me, by a meflenger, a fmall veflel full of water, in which was a
fubllance about half as big as a pea, and informed me that it was a
mineral, and called natural light ; being a part of what had been
given to a chymifl in the town where he then was, by a perfon who
had received it as a prefent from fome other, and the half of it was
now fent to me. My friend alfo informed me, that he had himfelt
feen, that when taken out of the water and laid in a perlbn's hand,
a vapour and fmoke ilfued from it, and, upon being carried in the
hand into a dark place, it emitted a light fimilar to that produced
from rotten wood. Upon viewing this, I immediately judged it to
be the fame kind of fubflance as that which I had received from the
German gentleman ; for, upon viewing it with the naked eye, and
trying the fame experiment of its efFe6l, the whole were as exadlly
alike, as if it had been broken off from the fame piece ; I there-
upon fet about a diligent examination of this fubllance, and noted
the following particulars in it.
I poured the water and this fubflance in it out of the veflel, and
cut off, while it was under the water, a piece or particle, about
the fize of a pin's head, having firfl prepared a glafs to receive it
and make my obfervations. Having put this particle on the glafs,
I immediately placed it before the microfcope, and law lying about
it a fmall portion of fome kind of moiflure, and the particle itfelf
appeared like a dark body, excepting only, that in two places, there
was a fmall luminous appearance : I alfo faw a great number of
particles, which I deemed to be globules, in violent agitation one
among another ; thefe globules were collected in two places on the
Hh2
( 244 )
particle, and tlien were, as it were, driven off from it, and when
they had got to about five or fix hairs' breadths from the fubllance
of the particle, they difappeared. All thefc globules, viewed by the
naked eye, exhibited the appearance of fmoke : foon afterwards,
feveral fmall luminous parts appeared on the particle, which by de-
grees increafed fo far, that through the microfcope, they gave me
the reprefentation of a piece of burning turf, with fome afliy parts
here and there covering its furfacc.
But what I moll wondered at was, that what I have fiiid gave
the appearance of fmoke, did not difperfe itfelf in the air, nor
mount upwards, as we obferve common fmoke to do, but fell back
on the glafs. lb that round about this particle of fubftance, cidled
natural light, there was not only more moifture tlian before, but
at the diltance of half an inch from it, there lay a very tranfparent
moifture or liquor, confiding of minute round jiarticles of different
fizes, and thefe in fuch numbers, that it was wonderful to behold :
many of thefe feemed to be watery, others oily particles.
After this particle had laid a whole night, I examined it again in
the morning, and then I law that the fubllance which feemed wa-
tery, was increafed, and that the minute globules, exhibiting the
appearance of fmoke, ftill iffued from the particle. I then carried
it into a dark place, to fee whether the fame kind of light was
emitted from it as 1 had feen the evening before, but I could not
diltinguiili any.
After it had remained twenty-four hours in my clofet, expofed to
the air, I again examined it, but I could not perceive any thing
expelled fr®m it. I then lighted a candle, excluding the day-light,
that I might fee more acutely, and then I faw fome globules ex-
pelled, which I think was principally caufed by the heat of the
candle ; for I obferved, that all the moill part of the fubflance
which had been expelled, was evaporated, and fome faline particles
of irregular figures were coagidated.
( 245 )
Moreover, I prepared a glafs tube, in which no liquor had ever
been, and taking one half of this fubltance, called natural light, out
of the water, I wrapped it in blotting paper to dry up any part of
the water which might adhere to it. Being thus dried, I put. it
into the glafs tube, with intent to clofe the orifice by heat, fird
uling the necellary precaution that the glafs might remain cold, ex-
cepting the bare end, which I clofed by applying it to the flame of
a candle.
Having thus clofed the glafs, I examined the fubftance I had put
into it, and faw an incredible number of globules ifluing from it,
producing round about it an appearance of vapour or fmoke, and
at length forming a collection of watery and oily matter, which
gathered about the particle in fuch quantity, that, after an hour's
time, they impeded my view of the globules which were expelled :
whereupon by llrongly Ihaking the glafs, I removed the particle into
a freflr place, and then, again examining it, I faw the globules
expelled from it in as great numbers as before, and after three
hours, they formed fuch a colledion of moillure, as again to inter-
cept my view of the globules as they were expelled.
I brought the glafs, containing this fubliance, near to the heat
of the candle, and immediately placed it before the microfcope ;
and then I faw, not only a great number of globules expelled from
it, but alfo many globules expelled from that part which had been
converted into a liquid ; and in fome places I faw that the heat had
changed the liquid into hard or folid corpufcles, to \vhich, by reafon
of their minutenefs, I could not alhgn any determinate fliape, and
which, to the naked eye, reprefented a white appearance.
I again brought the glafs to the candle, and expofed it to a greater
degree of heat, imagining that when, in this clofed glafs, I had
driven the liquid from one place, I fhould find it colledcd in another,
but in this I was mifiaken, for all the moifiure was changed into
rigid corpufcles, and though, on the next and following days, 1
( 210 )
examined the lubftancc in the glafs, I could not perceive any
nioillure.
The piece of this fubftance which I had left remaining I put into
a glafs tube, the cavity of which was not larger than the tip of a
child's little finger, whereas the former tube was more than three
times that lize. This I examined by the microfcopc, placing the
particle in a fomewhat oblique point of view, and then, not with-
out wonder, I perceived the globules expelled from it ; which, to
the naked eye, appeared as fmoke, not rifmg up on all fides, as is
iiniverfally obferved in common fmoke, but, on the contrary, that
they tended downwards.
To illurtrate this, let A B C D, Plate XVIII. fg, \, reprefent tliis
piece or particle of fubllance, which is called natural light, and let
A be fuppofed the lower and C the upper fide of it, and in this po-
fition the globules, expelled between £ D and G, were driven down-
wards, that is, towards H, and, in like manner, the globules be-
tween E B and F were driven towards 11 ; and \\'hen I made B
the lower part, all the expelled matter took its courfe towards K,
and if D was made the lower part, then it all tended towards I,
This expulfion of globules lalled only two or three days, and, as I
faw no farther alteration for the fpace of two or three weeks, I laid
the glafles afide.
This fubllance was fent to me on the fifteenth of April, lOgs,
and in the middle of Auguft, in the fame year, I looked at the firrt
mentioned glals, when I was greatly furprifed to find that it feemed
to be all vaniftied out of the glafs, whence, at firft, I doubted whe-
ther this was the real glafs which I had ufed : but, feeing a great
quantity of tranfparent moifture in it, I became more fatisfied that
it was the same, and the more fo when, upon warming the glafs and
the moifture which adhered to it, towards the warmth I faw the
moifture immediately change into a white fubllance. I then exa-
mined the other, and the fmaller glafs tube, which was still clofed
up, and I could not difcern any alteration in the contents.
( 247 )
in order to give a better idea of the manner of making my ob-
fcrvations on this fubjedl, I will explain how I prepared the fecond
and Imallell glafs tube which I ufed.
I took a glafs tube, of the length and fize reprefented at ^^g". 2,
A B, and by the help of a brafs pipe, which goldfmiths and other
artificers ufe to folder fmall pieces of work, which they call a blow-
pipe, and by applying with it the flame of a candle I blew at the end
of it the fphere or glafs globule, fig. 3, FDE.
When this fphere and the whole glafs was cooled, I dropped in-
to the opening, C, the particle of the before mentioned fubftance,
called natural light, which relied at the place E : I then took the
fphere between my fingers, that when I fhould again approach the
tube to the fire, there might the lefs heat reach to the fphere, then,
directing a llream of fire to the tube, at G, until the glafs was hot
enough to be extended, I gave it the figure fhewn at fig. 4, H I K L.
I then broke the glafs at the llender part, H, and the tube then was
of the Ihape fhewn at fig. 5, M N O P, and when the glafs was again
cool, I brought the orifice, M, to the flame of the blow-pipe,
whereby the glafs immediately melted, and the orifice was doled.
This glafs having remained clofed up for lb long a time as I have men-
tioned, I broke off a fmall piece at M, caufing an aperture about
the fize of a pin, and from which the air rulhed out with lb much
force as to produce fomething of a noife. I then immediately ob-
ferved the fubfiance in the glafs, and faw the globules driven from
it in as great numbers as if it had been but newly put into the glafs.
I examined it feveral times the fame day, and conllantiy faw the
expelled matter tending downwards, as I have before dcfcribed.
The following day the matter was fo diminifiied that two fmall
cavities were formed in the middle of it, and the moifture was fo
much increafed that the matter fwam in it. In the evening of that
day two third parts of the folid fubilance were wafted : I then took
the piece out of the water, and faw the globules expelled from it
as large as ever.
( 2^8 )
On the morning of the third day after the glafs had been opened,
I examined it, and faw that b\it a linall part was remaining, yet the
globules were expelled with the' fame force ; in the evening, about
nine o'clock, it was diminiflicd to lefs than the fize of a large grain
of fand, and yet globules were expelled from it, though in no great
number, by reafon of its minutenefs.
On the fourth day there remained no more than the fize of a fmall
grain of fand, yet the expulfion of globules ftill continued: in the
evening there was nothing remaining of it defcrving to be men-
tioned, nor did I fee any more globules illuc from it.
During the courfe of thefe my obfervations I have often conli-
dered what might be the caufe why flame is fo eafdy produced from
this fubftance, but have not been able to fatisfy mjiclf on that
head. This, however, feems certain to me, that this fubrtance may,
in great part, be kejjt out of water undiminiflied, provided it be pre-
ferved from communication with the air, and clofed up in fome vef-
fel, as I have mentioned.
If any pcrfon lliould imagine, on reading my defcription of the
glafles fabricated by me for thefe and my other obferv^ations, that I
am verfed in the art of glafs-blowing ; I mull inform him, that the
only knowledge 1 have therein was acquired from thole artills who,
at our fair-times, came to exhibit the manner of blowing in glafs
by the candle or lamp ; and, by obferving their manner of working,
I have learned fulBcient to qualify myfelf for preparing glalles to
anfwer my feveral purpofes.
The Sting of a Gnat, as defcribed hy Stvammerdam, JJieivn to have
been erroneonjly pidured hy him. The Author s de/cription of the
Gnat's Sting, and alfo of that of the Horfe-jly, and the Feathers
on the ivings of Gnats.
JJOCTOR John Swammerdam has lately printed and publiflied
to the world a figure of the Gnat, as drawn from the microfcope,
and particularly its Hing out of the cafe or flieath, which fting is
pictured exceedingly pointed and flender, and extended to a great
length from the (heath. Upon viewing this figure, I could not per-
fuade myfelf that the fting was, in reality, formed in the manner
there exhibited ; for I was well allured that, if of fuch a fliape, it
mull either be bent or broken when thruft into the ikin ; nor could
I eafily believe that in the head of a Gnat, or in the fore part of its
body, tliere could be contained mufcles or organs of fufficient length
and ftrength to give the fting its necessary firmnefs. For thefe rea-
fons I determined to examine into the true formation of the Gnat's
fting, and I was alio defirous of difcovering, if poflible, the reafon
of the great pain it excites, and of the fwelling on the Ikin caufed
by the pundlure.
I could not difcover that the Gnat, when ftinging, protruded the
fting from the extremity of the flieath (though I thought I faw,
rather obfcurely, a fmall part of the fting fo protruded), but I al-
ways found that the Gnat made a wide opening on one fide of the
ftieath, in like manner as if one was to hold a fword in a flieath, the
leather fides of which were laid together in fuch a manner that, when
the fword was to be ufed, it would not be neceflary to draw
Vol. IL I i
( 250 )
it wholly otit, there being an aperture left on one iide of the flieath,
which might be opened by a touch.
Having taken out the iHngs of many Gnats, through this opening
in the fide of the flieath, and having examined fcveral Gnats, who
protruded their Itings, fome in part and others to their full extent,
througli tlie fame aperture, I fancied that I faw the extremity of the
lling to be pointed like a spear, and to be barbed or jagged on each
fxde. But, on more narrowly examining the ftings I had extracted,
I found I had been miliaken in this : that what I at firft took for one
fmgle lling was, in realit}^ compofed of four parts, for, out of w hat
I before deemed to be only one I took tw o liings, each having hooks
or barbs at the ends ; the third part, from which I took tliofe two
(and which might alfo be called a fting), was open on one Iide, in
like manner as I have mentioned refpeAing the flieath, and termi-
nating in a point, and appearing, through the microfcope, like a quill
cut fl oping: the fourth piece, which was exceedingly thin, feemcd to
be placed round about the lall mentioned fling, but, when I exa-
mined it more narrowly, I faw that it alfo lay in the cavity of it.
When I had feparatcd thefe four pieces of the flmg from each
other, they did not preferve their ftraiglit figure, but became fome-
what bent, efpecially thofe two which had hooks on them, fo that
I could not place thefe two laft before the microfcope to my ^\ ifli.
Hereupon I vv^as obliged to cut afunder thofe four pieces, and gi\'e
diflindl drawings of each of them from the microfcope, in order to
fliew to all men, and in particular to my own countrymen, (wlio I
fuppofe are more tormented with thefe infctls than the people of
other nations, by reafon of the many flanding waters we have, where
they breed in great multitudes), this wonderfully formed and mi f-
chievous weapon in the Gnat.
To place all thefe things in a clear and diflindl view, I will firft
exhibit the figure of the Gnat's fling, as defcribed by Swammerdam,
and which he says he himfelf has feen. Plate XV III. Jig. 0. A B
C D E, is, as Swammerdam fays, the fling of the Gnat, with its
( 251 )
fiieath or cafe, A B D E being the cafe, and BCD the fting, M^hich
fting, he fays, is fo Iharp at the extremity, that he could not, with
his beft microfcopes, difcern the point.
FJg. 7, reprefents the Iheath and the flings of the Gnat, as placed
by me before the microfcope, and drawn by the limner from the
life, by my diredlion, F G H I is the cafe or llieath, which the Gnat
opens on the fide, at G H I, in order to protrude the flings when
it is going to flrike : this llieath is covered with hairs, and between
them with many fmall feathers, but which feathers are fo clofely
joined to the body of it that they are rarely to be feen. H K is a
part of thofe four organs or flings, as they are regularly placed be-
fide each other, and at fuch a diflance from the Iheath as the Gnat
protruded them of its own accord, and not forced out by me, unlefs
in killing the animal I did it inadvertently. At K are feen the barbs
or hooks with which the flings are furniflied. The colour of thefe
flings is like that of tranfparent tortoifefliell. F I is that part of the
llieath and flings cut off next the Gnat's head.
Fig. 8, LMNOP, reprefents that part of the fling, or fecond
cafe, from which I extracted the two other flings, the points of which
are furniflied with hooks. This has an opening from end to end,
through which the other flings may be protruded, in like manner
as I have mentioned refpeding the firft flieath : I have alfo, through
this opening, oftentimes drawn out all the three flings which lie
within it.
L M Q O, is another piece, lying upon the former, and, being
fomewhat broader and longer than the other, feems as if defigned
to cover it like toother flieath, but I have often drawn it out of the
cavity of the piece LMNOP.
Fig 0, RST, reprefents in part all the flings, and here may be
difcerned the two inward ones that are barbed, exhibiting the fame
appearance as at H K. Thefe two interior barbed flings are won-
derfully thin but not flat, for if fo they would, by their thinnefs, be
unable to bear any force, and flill lefs have power to perforate the
li 2
( 252 )
Ikin. But they have a third fide on the back of each of them, and
their figure, in that refped, i& hke that of a fmall f\vord,which, by
reafon of its fmallnefs, muft neceflarily have a third fide to give it
Itrength, agreeing, in that refpcdl, with thefe llings of the Gnat.
Hitherto it has appeared no otherwife to me tlian that each of
thefe barbed llings has the barbs or hooks only on one fide, and
M'hen they He on the infide of their cafe, or more properly, within
the thickeft of the flings, their flat fides are clofe together, and
thofe fides which are barbed lie on the outfide, fo that when all the
pieces of the fling are placed together in order, they exhibit, when
taken out of the flieath, the appearance of a fingle fling barbed or
hooked on each fide.
Fig. 10, V^WX, reprefents one of the two barbed flings taken
out of the cavity of the other piece, one of them being a little
longer than the other.
Fig. 11, a b c, reprefents a part of one of the two laft mentioned
flings, which, by reafon of its exceeding thinnefs, was bent in this
fliape, but in this pofition, the hooks or barbs cannot be diflin-
guifhed ; placing the flat fide of this before the micro fcope, the
point of it appeared as Sitjig. 12. Upon turning it round a httle,
the point appeared as a^t Jig. 13, and turning it flill more, the hooks
became vifible, as is Ihewn at^g". 14.
If we confider the formation of thefe flings, though we know not
how the Gnat flrikes them into our bodies, or moves them about
when there, we may, never thelefs, eafily conceive, that when
driven within the Ikin, they may make a very fenfible, though mi- -
nute wound, and by reafon of their length, a much deeper one
than is occafioned by lice, fleas, or other fmall vermin. Again, fo
long as the Gnat is fucking the blood which iflues out of the
wounded veflels, there will not any fwelling appear. But when
it draws out the flings, the juices of the wounded veflels continuing
to ilTue, there muft neceflarily arife a greater fwelling than ufual,
becaufe, as I before faid, the flings enter fo deep, and another rea-
( 253 )
fon is to be attributed to the minutenefs of the flings, which make
fo fmall a wound, that the Ikin, efpecially that part next the fur-
face of the body, clofes immediately upon the extraction of the
lling.
If any perfon fliould be defirous to follow my example in the ex-
amination of the Gnat's fting, I caution him to arm himfelf with
patience in the purfuit. I have often opened the flieath or cafe
incloflng thefe ftings, and taken them out as they lay regularly
placed betide each other, but to feparate the four parts or pieces of
this fling, and to place them before the microfcope, fo as to give a
dillindl view of them to others, requires no fmall labour and pains.
I have deftroyed above an hundred Gnats in accomplilliing this
purpofe, and have been obliged to repeat my obfervations many
times, for though I could fee all the pieces, and did my bell to fix
them before different micro fcopes, it often happened, that while I
was bulled with one of them, I lofl light of another ; for which
reafon, I was obliged to make new trials and obfervations many days
together.
I thought it would not be amifs in this place to give a figure of one
of the two llings which the large Flies, commonly called Horfe-flies,
carry in a fheath in their heads near the mouth ; which, as drawn
from the microfcope is fliewn at Jig. 15, AB C D, and I have caufed
this drawing to be made, not only to fhew the nature of this fling,
being of a flat fhape and very fharp, and with which the animal
torments horfes to that degree, that they kick and leap about the
field even at the fight of that Fly, but alfo to point out that as the
lling from D to C, is exceeding thin and fharp ; fo from C to B,
where it tapers to a point, it grows thicker and thicker to the very
extremity at B, by which means it is of the fame llrength through-
out ; fo that, in a word, we cannot but obferve the greatell perfec-
tion in the formation of the fmallefl animals.
The feet of a Gnat, and its whole body, are covered with very
beautiful feathers, one of which, drawn from the microfcope, is
( 254 )
iliewn at fg. 1 7 ; the wings alfo are covered with feathers. Fig,
18, is one of the wings of the lize it appeared to the naked eye;
^g. 19, ABC, is the fame wing fomewhat magnified, in order to
Ihew, not only that the whole border of it, ABC, is covered with
large and fmall feathers, but alfo the nerves or bony parts, D DDD,
whicli give llrength to the wings. One of thefe feathers magnified^
is lliewn zt Jig. 20. The membrane or thin Ikin between thefe parts,
appears, when viewed by the microfcope, to be covered with a great
number of exceedingly minute particles elevated above the Ikin, and
thefe, upon a clofer examination, I found to be, in truth, hairs :
they are to be feen at fig. 2 1 , which is a Iketch of a fmall portion of
the whole wing. ABC, arc the feathers on the border, and AD E C,
the hairs on the membrane of the \^'ing.
4-
Oti the Nature of Ivfeiifihle Perspiration, with the Author s method
of computing the quantity of moijiure ivhich iff ues from the human
hodijy by that evacuation.
11 AVI NG had a difcourfe with a certain medical gentleman on
the fubjeft of what is called Infenfible Perfpiration, or the great
quantity of matter or fubllance which ilfues from our bodies, and
which we are unconfcious of, 1 determined to make an experiment
on this fubject, by an obfervation of the perfpirable matter ifluing
not from my whole body, but from one of my hands only.
For this purpofe, I took a glafs jar, wide enough to admit my
hand, which jar, as far as I knew, never had any thing put into it,
except clean rain water ; and having wiped it as dry and clean as I
could, I put my left hand into it, Hopping the aperture round my
wrift with a cloth, that none of the perfpirable matter might efcape
from the glafs, and I then began to drink tea until it not only
warmed me, but brought on a moderate perlpiration.^'
After fome time had elapfed, I perceived the perfpirable matter
ilTuing from my hand, colledled on the inlide ot the glals, exhibiting
the fame appearance as when in fummer time, a bottle of wine is
brought out of a cool cellar into the warm air^ whereupon the
moirture in the air will condenfe and fettle on the glafs round the
wine. Soon after this, the moiflure was fo increafed, that it ad-
hered to the glafs in fmall drops, and at length thofe drops ran down
and fettled at the bottom of the glafs. After I had kept my hand
in this fituation three quarters of an hour, I took it out of the glafs,
and with all the accuracy I was able, I weighed the perfpirable
matter which had illued from it, and found it to be the fixtecnth
part of an ounce.
In the latter end of the month of January, I repeated my obferr
vation, by again putting my hand, while it was A^ery cold, into the
glafs, and fitting down b\ the fire, I began to drink tea, fo hot and
fo plentifully, as to produce a copious perfpiration ; and after keep-
( 256 )
ing my hand in the giafs a whole hour, I collected the perfpirable
matter, .and found it to wiigh tln-ee thirty fecond parts, being a
lixtcenth and the half of a fixteenth part of an ounce;
Hereupon, I began to coniider and realbn thus with myfelf ; if
the perfpiration in every part of one's body is in the fame propor-
tion, as in the experiments with the hand, how great a quantity of
moillure mull iflue from our whole bodies, and how necellary mull
it be when we take any medicine to promote perfpiration, that we
fliould alio recruit our llrength by fome reftorative liquor, fuch as
either wine and water fweetened and boiled with the yolk of an
egg, or elfe drink meat broth ; efpecially if we confider, that the
health and ftrength of our bodies depends on the juices.
In order to make an eftimate of the , roportion the hand bears to
the whole body, I filled the before mentioned glafs jar with water to
the brim, and having placed it in a larger vell'el, I thrull my hand
into it : the water which ran over, and was equal to the lize of my
hand, I collected, and found it to weigh eleven ounces- I am in
deed aware that we cannot make a true computation of the furface
of the body by that of the hand, becau e the hand is furnillied with
fingers, from which the perfpirable matter illues. However, if the
perfpiration is the fame throughout the body as in the hand, I
will venture to fay, that according to my preceding obfervations,
I fliould perfpire in an hour's time, about the quantity of twenty
ounces. For I reckon my body to weigh one hundred and fifty
pounds, and my hand eleven ounces, and I compute that eleven
ounces weight of water contain eighteen one-third cubic inches,
and this I fet down as the folid contents of my hand. Farther, I
reckon that fixty-five pounds weight are a cubic foot of water, and
contain 1 728 inches; and according to this calculation, we fliall fee
that the fize of my whole body is almost two hundx-ed and eighteca
times larger than that of my hand.
+?/>
On the propagation and rapid incrcnfe of the common Fly : the
manner in ivhich the common Nettle produces pain and infiam-
viation explained.
A SURGEON of fome eminence in thefe parts, happening to meet
with me, lliewed me a piece of glandulous or fungous fubftance,
about the fize of a finger's nail, which he had taken from the dif-
eafed leg of a certain gentlewoman, whofe leg from the foot to above
the knee, had for fome years been uncommonly covered with thofe
kind of tumors, and he told me, that having waflaed this fubllance
in brandy, and afterwards cut it open, he had perceived in it a num-
ber of minute maggots : thefe he produced to me, but they were
fo fmall, that I could not diftinguiili them without my fpedacles.
A piece of this fubllance was put into my hands by the furgeon,
in order that I might examine into the nature of thofe maggots.
Upon my return home, I examined them by the microfcope,
and was immediately convinced that they had been produced from
eggs laid by fome Fly upon the difeafed part, and I had no doubt,
that from them would be produced other Flies of the fame fpecies
with that which had laid the eggs. This I commxinicated to the
furgeon, who, at firft, did not give much credit to it, as not being
able to conceive how any Fly could find its way to the part to lay
thofe eggs.
In purfuit of my inquiries, concluding that the piece of flefli on
which thefe maggots were found, would very foon be confumed by
them, 1 fupplied them with other pieces of meat, which they alfo
devoured ; and I continued to feed them with frcfh meat until the
fifth day, which was the lall day, when, preparing again to feed
Vol. II. K k
( 258 )
them, I found, to my great furprife, that having left the box which
contained them open to give them air, they had all crept out of
the box, and it was not till after a diligent fearch, that I found
many of them (for they had been fifty in number), in the corners
and chinks of my fcrutoire : they had in thefe five days grown to
fuch a fize, that each of them was as long as one of my nails ; and
the reafon of their quitting the box, 1 concluded to be, that having
grown to their full fize, and requiring no more aliment, they con-
cealed themfelves in holes and corners, in order to undergo their
next transformation.
The next morning, being the firft of Auguft, one of thefe mag-
gots, whofe body had been lliarp or pointed at one end, was con-
traded one third in length, fo as to be of an equal thicknefs at each
end, and exhibited the figure of a fmall barrel : in the afternoon of
the fame day, four others of the maggots had alfumed the fame Ihape,
and they were changed from their original white, to a yellowilh
colour : the next day they became red, and fo all the maggots, from
day to day, changed from a yellowifli to a red, and at length to a
blackifh colour.
Two of thefe cryfales or grubs I put into a glafs, and carried
about in my pocket, with intent to expedite their change into Flies,
but after five or fix days, I found the heat was injurious to them,
for they began to flirivel up, and confequently, I judged, would not
produce any living creature. The others I placed on a paper, co-
vering them with a glafs, and at the end of nine days, I opened
three of them, and took out of each a perfectly formed Fly, but
very moift, and without any motion that I could difcover ; they
were inclofed in a thin membrane, befides the outfide hard fliell
which contained them. I could not at firfl; difcover their wings,
but examining them more narrowly, I perceived the wings folded in
exad order on their bodies, and having feparated them from the
bodies, I found them to be perfedly formed ; upon opening the
bodies of thefe unborn Flies, I took out of one of them a great
quantity of eggs.
( 259 )
On the fourteenth of Auguft, I faw four fully formed Flies flying
about the glafs, and that the fhells or velicles from which they had
ifTued, had a hole at one end : upon my putting fome fugar under
the glafs, the Flies immediately fed iipon it.
The next day all the other aurelias or grubs produced living Flies
except two which I had injured in the handling, and at the fame
time I perceived many other Flies on the glafs in my clofet, which
T concluded came from the maggots which had hid themfelves as
before mentioned. I placed before thofe Flies fome pieces of raw
flefli, but none of them would feed on it ; neverthelefs, on the
eighteenth of Augull:, they all fed greedily on a piece of flelli.
On the twenty-eighth of Auguft, I opened three of thefe Flies,
and took out of one of them a great quantity of oblong eggs, each of
which was a twenty-fifth part larger than the eggs I had taken out
of the Flies which were not hatched ; and what appeared to me
worthy of note was, that to each of thefe eggs was fixed an ex-
ceeding fmall black vefl'el, through which I conclude each egg had
received its nourilhment. All thefe minute velTels arofe out of
larger and darker coloured velfels, and thofe again out of a much
larger one ; all which veflels I therefore concluded to be arteries.
Examining thefe arteries with great attention, I very diftin(3;ly per-
ceived them to be formed of annular parts, like the veflels in the
lungs of animals, but thefe annular parts were fo exceedingly mi-
nute, that, viewed through microfcopes of very great magnifying
powers, they appeared as slender as a fine hair of one's head iccn
by the naked eye.
Though thefe Flies appeared very vigorous, yet a fmall touch or
prefliire would caufe them to die ; for happening to break one of
the glafles in which I kept them, whereby they efcaped, and flew
about my ftudy, though in catching them I handled them as gently
as I was able, they died in a few days ; fome lofmg their wings, by
which I had caught them, others the ufe of their legs, and laying
on their backs motionlefs for feveral days,; and I concluded their
Kk2
( 2G0 )
deaths to be occafioned by this, that in touching them, fome of
thole minute vell'els might be injured, and many of the eggs de-
pending on them be broken off, and putrefying in the body, jnight
occalion death. At length, on the feventh of September, 1 had
only two Flies left alive, one of whicii had loit a \ving. Thefe 1
judged to be a male and a temale.
On the ninth of September in the morning, I found one hun-
dred and forty-five eggs laid, as I judged, by one Fly : fojne of
thele eggs, with a piece of dried fleth, I put into a glafs and carried
in my pocket, the weather being cold, to fee in what fpace of time
maggots would be produced from thofe eggs, and I found fome of
them hatched the very fame day. The next morning all the others
were hatched, and I found that, in that one night's time, they
had all grown twice the fize of the eggs.
I again put fome more eggs into a glafs, and carried them in my
pocket, and in five hours time they were all hatched, and in fevcn
hours more they were grown to twice their original fize, fo that I
concluded for certain, that the maggots which had been brought to
me on the piece of flelh taken from the gentlewoman's leg, had been
produced from eggs laid on it at the lafl drelhng, by fome Fly, and
that when brought to me, they had been hatched but a few hours.
I caufed drawings to be made of the Maggot, the Grub, and the Fly,
I have here defcribed, becaufe thefe Flies are the largeft fort found
in our country. Plate XVIII. fg. 21, is the maggot when grown
to its full fize and five days old. Fig. 22, is the cryfalis, aurelia,
or grub into which the maggot was transformed, and at one end of
it appears the hole through which the Fly iflued. Fig. 23, is the Fly:
and unlefs 1 had been convinced by my own experience and infpec-
tion, it would have feemed incredible to me, that fo large a Fly
could proceed from fo tmall a grub ; but we muft confider, that the
wings, and alfo the hairs with which the Fly is covered, are placed
as clofe as pofilble to its body, while in its aurelia or cryfalis ttate;
but when it becomes a perfecl Fly, they feparate from the body.
( 2G1 )
and rife up at fome diftance from it, and confequently appear larger
than they are in reality. *
I know many people aix; of opinion that flies are produced from
corruption, and they pretend to bring many inftances in fupport of
that notion, which occuned to me lately in converfation with a cer-
tain learned gentleman, who argued thus upon the fubject :
" I have obferved," fays he, " in a parcel of grubs or av^relias,
" produced from fome caterpillars of the fame fpecies, four butter-
" flies produced, all of the fame kind and fliape, and from the fifth
" aurelia, which had an aperture like the others and was tranfpa-
*' rent within, three common Flies illued. The caufe of this ap-
*' pearance 1 could not account for."
Tq this gentleman I made anfwer, that thefe reafonings of his
made no difficulty with me, becaufe I conceived the matter might
be accounted for as follows :
Flies, and almotl all living creatures which are not able to nou-
rifli their own young, have it implanted in them by Nature to lay
their eggs in thole places where the young, when hatched, may
find food. When, therefore. Flies of any description cannot find
any flefli, fifli, or ofl'al, they often lay their eggs in thofe places where
their infl:incl informs them their young will find fubfillence, and this
is in the grubs or aurelias of caterpillars; the maggots hatched from
thefe eggs laid by the Fly can ealily perforate the thin coat or cafe
of the aurelia, and ufc for their nourilhment that fubllance within
it, which was deftined to the formation of a winged creature of a
dilFerent fpecies, fo that from fuch an aurelia a Fly inftead of a but-
terfly may be produced. With this argument of mine the gentle-
man declared himfelf to be fatisfied.
Now, I lay it down for a certain truth that it is equally impofiible
for a Fly, or other living animal, to be produced from corruption,
as for rocks to bring forth horfes or other beafis.
* Anotlier rcafon may be affigned for this appearance, namely, the rapid growth of fly.
ing 'nfcfti iinmodi ifcly after thoir coming forih from their aurelia ilate. See the Tranflator's
remark on this fubject in a note. Vol. I. p. 28.
( 262 )
Many perfons cannot lufficiently wonder at the immenfe quanti-
ties of Flies with which the inhabitants of a befieged town, of any
note, are infefted. Bnt we may eafily folve this difficulty, when we
confuler that it is impollible for the commanding officers to caufe all
the bodies of the llain to be interred, and that from them, and from
the entrails and offal of beafts, left expofed in the fields, the num-
ber of Flies mull increafe beyond mealurc. For, let us fuppofe that
144 Flies in the firii month. in the beginning of the month of June,
,,.,.-• r J r 1 there Ihall be two Flies, a male and a fe-
72 of which fuppofed females.
144 eggs laid by each female, male, and the female Ihall lay one hun-
~~ dred and forty-four eggs, which eggs, in
2S8 th I beginning of July, lliall be changed
Z into Flies, one half males and the other
10368 Flies in the fecond month, j^.^f females, cach of which females fliall
5184 of thofe fimaies. lay the like number of eggs ; the number
144 eggs laid by each female. ^^ pjj^^ ^.^ j^j^^^nt ^ ten thoufand :
20736 and, fuppofxng the generation of them to
proceed in like manner another month,
their number will then be more than
5j^^ proceed in like manner another month.
74G196 Flics in the third month. , , , , ,- , ,, , ,
leven hundred thouland, all produced
from one couple of Flies in the fpace of three months.
Confidering this we need not wonder at the great multitudes of
Flies obfcrved where the bodies of great numbers of men or ani-
mals lie unburied.
There is a wondcrtul circumftancc, and ^^■cll wortliy of note, in
regard to Flies, namely, that the maggot from which a Fly is pro-
duced will come to its full fize in the fpace of five days : for, if a
month or more was required for this purpofe, as is the cafe with
other maggots, it would be impolTible for Flies to propagate their
kind in the heat of fummer, bccaufe the Fly's maggot can fcarcely
ever have any food than what is found in the place where the egg
was firll laid. Now this food of theirs, namely, fifli, flefli, or oflal,
lying in the open air and expofed to the fcorching heat of the fun,
( 2C3 )
would continue but for a very few days to be fit food for the mag
gots, therefore the All-wife Creator has implanted in thofe mag-
gots the property of acquiring their full growth in a very few days,
when, on the contrary, other maggots which can have a continual
fupply of food, are months before they undergo any alteration.
I have, at times, carried feveral of thefe maggots about me in a
glafs, giving them every day a fupply of flefli, and fhewed them to
feveral curious perfons, that they might with me obferve their won-
derfully rapid growth ; I have, indeed, brought them to their full
fize in the fpace of four days, fo that I conceive in the heighth of
fummer the eggs laid by Flies may, in lefs than a month's time, be-
come complete Flies, fo as again to lay eggs. Lattly, it is worthy
of obfervation that thefe maggots do not void much excrement, fo
that the greatell part of the fubllances they confume for food enters
into the compolition of their own bodies.
AT the time I firft turned my thoughts on the nature of our com-
mon ftinging Nettles, I imagined that the great pain and fwelling
they occalion arofe from the Iharp points of the tHngs or prickles,
which are thick fct on their leaves and lialks, being broken off and
left within the Ikin : but happening one day, while gathering afpa-
ragus in my garden, to be Itung between my fingers by a very fmall
Nettle, it produced fo uncommon a pain and fwelling, that 1 exa-
mined more narrowly the formation of Nettles by the microfcope,
and I found that the filings or prickles are not only hollow, and con-
tain within them a very tranfparent juice, but that, at the time
when they are in their moll vigorous growth, this juice ilfues from
the flings, and may be feeu to fettle on the points in the fliape of a
very fmall drop or globule.
Upon feeing this, 1 formed a different opinion on the fubjed:, and
I conceived that, though we may be pricked by the Nettle no
deeper than the external cuticle or fivin, and though the point of the
filing may not be left behind, yet w'e fliali experience both pain and
( 204 )
fwelling, if the liquid, Avhich is at the extremity of the fting, or can
by any means be expelled from thence, penetrates \N'ithin the fenfi-
tive part of the ikin, and there touches or wounds any of the vef-
fels ; whereupon fome acute fait, which this liquor contains, prin-
cipally produces tlie pain and fwelling we experience ; and this I
rather take to be the cafe, becaufe, on examining Nettles which had
palled their full growth, I found that the juice in many of the ffings
was dried up, whereas thofe that were ftill growing were not only
quite full of juice, but fome of it iflued from their points ap before
mentioned. And I obferved the points of thofe which had come
to their full growth, to be for the moft part broken, which I attri-
buted to the wind agitating the leaves, and ftriking the llalks one
againft another.
I know many people fay, that if we boldly grafp a Nettle it will
not Ring, but the only reafon is this, that if we feize a Nettle with
the whole hand our lingers are clofe together, fo that the Nettle
only touches the Ikin on the infide of our hands and fingers, which
is generally fo thick and tough that the flings cannot pierce it, but
are either blunted or broken, and therefore we feel no efFe<ft on the
infides of our fingers, much lefs the palms of our hands ; but the
parts between our fingers, where the Ikin is thin and foijt, are thofe
liable to be injured.
In order to Ihew the formation of the ftings of the Nettle, I
liave caufed drawings to be made of them from the microfcope.
, Kate XVUT. fg. 24, ABODE, is the fting of a Nettle, as it
gro'N^s on the leaf or flalk, -when in its moft flourifhing ftate. At
C is to 1)0 fcen a round drop or globule, being part of the juice with
which the cavity of the fting is filled. A B 1) E is a foft, green,
flexible part, which has this appearance while on the plant, but,
when feparated from it, in a little time more than half of it dries
away. BCD is the fting itfelf, which is very tranfparent when
filled with juice.
( 265 )
Fig. 25, F G H I K, is the fling of a Nettle in its vigour, at tiir
end of which, H, no juice is emitted.
Fig. 20, LRINOP, is the fting of a Nettle come to its full
growth, and in which the moifture which it contained in its cavitv
is dried up, as is fcen between MNO; and as in this fting we fee
feveral particles, which in the figure are marked i, 2, and 3, 1 ima-
gine that this evaporation of the juice from the fling was not per-
formed in one day, but at feveral times, one day more than another,
according to the heat of the weather. Between 3 and N, this fling
appeared very dark and of a greenith colour, which doubtlefs was
the folid fubflance of the juice in the fling there coagulated.
Fig. 27, QRSTY, is the fling of the Nettle cut tranfverfely to
{hew the cavity within, as appears at the letter S ; and QRTV is
the green and foft part dried up thus far.
Fig. 28, WXYZ, is a fling of the Nettle cut off nearer the
point, where the letter Y indicates the cavity.
4^
Vol. II. I 1
Of the shrimp.
1 HAVE often rctleded on the nature of fome forts of Ihell-filli,
fuch as Shrimps, Lobfters, and Crabs, in this rcfped only, that
they bear their mukitudes of eggs on the outfide of their bodies,
which, if we retled, mull neceflarily be fo, for othcrwife it would
be impolTible for thofe filh to produce fo great a quantity of young
as we find they do, becaufe their bodies being covered with an hard
fliell, cannot be dillended, and would not allow fpace for the
growth of their eggs, if they were always within their bodies.-
The eggs of our Sea Shrimps are not produced and brought to
maturity at any one particular time of the year as is the cafe with
moll other fifli ; for I obferve Shrimps to have eggs at all times of
the year ; I fpeak here only of thofe Shrimps which are caught
near this coall ; for I am told that the Shrimps about Amilcrdam,
at fome feafons, are all loaded with eggs, and the remainder of the
vear are dellitute of them.
But what I obferved beyond my expedation, and which is well
worthy of note is this : tiiat every Shrimp's egg, when come to
maturity, contained in it nothing but a complete minute Shrimp,
which not only I could fee lying in the egg in a circular polition,
with the tail turned over its head and laying on the back ; but,
when taken out of the Ihell, I could fee fome of its fcales, toge-
ther with the tail and fins ; alfo the head and eyes, and thofe limbs
or organs \\ hich iflue from the head, and which lay as it were folded
together near the feet. In fliort. Shrimps are completely formed
in the eggs before they are feparated from the parent.
Thefe eggs, for the realbn I have mentioned, not being capable
of expanlion within the body of the Shrimp, -are carried about by
( 207 )
the parent, being fixed between thofe organs or limbs, which we
call its feet, and there they are nouriflied and brought to full ma-
turity by a fmall firing or ligament ; being thus proteded by the
parent until the young Shrimp within is able to break through the
fhell and feek food for itfelf.
In order to view the nature of thefe imborn Shrimps, I took fe-
veral out of the fhells, and having placed them before the micro-
fcope, I fent for the limner, whom I directed to make as accurate
drawings of them as he could, without informing him what the ob-
jects were, and while he was employed in fo doing, he often faid,
" I do not know what I am drawing, but it feems to me to be a
*' Shrimp."
Plate XVIII. fg. 29, AB CD, is one of thefe unborn Shrimps,
taken out of the egg, which I extended as much as poflible from
the rounding pofition in which it lay ; but though I endeavoured to
take thefe Shrimps out of the eggs with the greatell care, yet I
could not do it fo completely, but that in one of them the tail ap-
peared moft plainly, in another the head, and in another the feet.
In this figure, A B D denotes the head of the Shrimp, but wherein
the feet and other prominent parts, which we fee in full grown
Shrimps with the naked eye, cannot be dillinguilhed, becaufe all
thofe parts are, as it were, clofely folded together next the head,
and are extended towards B. Fig. 3o, E F G H I K, is another un-
born Shrimp, which drawing I caufed to be made only becaufe here,
at the letter E, the fins can be plainly feen, together with the bony
parts deflined to give flrength to the fins. E F G is a part of the
yolk of the egg yet remaining.
Upon comparing the fize of the eggs from which thefe young
Shrimps were taken, with grains of common fcowering land, I found
them, for the mofl part, of the fame fize, though fbme were rather
larger and others fmallcr.
Some years after this I renewed my obfervations on Shrimps, in
order to dilcover the circulation of the blood in thofe animals, and
LI 2
( 268 )
in doing this my eye was taken with thofe two protuberant parts,
which are placed in the fore part of the Shrimp's body, and which
are commonly called its head, Thefe protuberances are the eyes of
the Shrimp, which it has a power of moving in every direction, fo
as to view all furrounding objedis.
Having taken out the tunica cornea or horny coat of thefe eyes,
and well cleanfed the inlides of them, I found that the tunica
cornea in this creature was very foft and flexible, in comparifon with
thofe in the eyes of flies ; and when placed before the microfcope,.
in order to view objedl^s through them, I found that fuch objedls ap-
peared with much lefs dilliridnefs and brightnefs than when viewed
through the optical organs of a fly. The reafon of this difference
I took to be, that in Shrimps, and many kinds of crabs, but more
particularly in Shrimps, they, being always immerfed in water, do
not require to be hard or tough, and, therefore, when expofcd to
the air and becoming dry, they contradl ; infomuch that thefe eyes
which, in their natural flate and united to the animal's body, are of
a fpherical figure, when dry lofe that fpherical fhape, and from
being convex become concave, by contra6ling inwardly.
I caufed a drawing to be made of one of the eyes of the Shrimp,
the fame fize as it appears to the naked eye, and this may be feen.
at Jig. 3 1 , X. Fig. 32, A B C D, fliews a great part of the Shrimp's
eye, as feen by the limner through the microfcope, and here may be
feen a number of optical organs in that fingle particle or fpot which
we commonly call the eye. But, as in many flies each optical or-
gan feems to be furrounded with a kind of border of fix fides, here,
in the Shrimp, each optical organ is contained in a kind of fquare.
In the figure, that which in every optical organ is reprefented by
a fmall circle, is to denote a cavity or finking, but which originally
was of a perfedl protuberant fperical figure, until the optical organs
in the Shrimp, upon drjing, became contrafted.
Fig. 33, E F G H I, exhibits another large portion of the Shrimp's
eye, placed in a diredl line oppofite to the fpedator. Between the
. ( ^^9 )
letters E F G K appears a kind of muicular part, void of optical or-
gans, and this part I concluded was what ferved to move the eye.
Farther, I concluded for certain, that in like manner as every op-
tical organ in the eye of a fly has its optic nerve, fo in the eyes of
Shrimps every optical organ mull have its proper optic nerve. I
therefore opened many of the eyes of Shrimps, and not only difco-
vered a great number of minute optic nerves, but alfo a great quan-
tity of pellucid particles, every where mixed with thofe optic nerves.
Hereupon I began to confider whether or no thofe pellucid particles
(which often appeared to me rather oblong and fomewhat crooked)
might not each of them be the cryftalline humour of one lingle and
individual optical organ, and that their being of the oblong and
crooked fliape I have mentioned, might be occafioned in the diffec-
tion of the tunica cornea, whereas thofe particles were, in their na-
tural ftate, of a perfedly fpherical fhape, and filled the whole internal
cavity of their refpedive optical organs. And, in this opinion I
was confirmed when, upon more carefully attending to the Shrimp's
eye, I perceived the tunica cornea to have a whitilh appearance, and
the optic nerves, in the parts towards the infide of the head, to be
of a dark appearance, and, when feparated frorrt each other, exhi-
bited a violet colour. I alfo concluded, that if it were poffible to
take out the eye of a Shrimp,, in fuch a manner as to preferve the
cryftalhne humours within the cavities of the tunica cornea in their
perfedl fhape, uninjured, I might place them before the fight, and
that, doubtlefs, I fhould fee the objeds through them as clearly and
difl;indly as when viewed through the eyes of flies.
In the next place, I was defirous of knowing what was the food
of the Shrimp, and I had obferved that the part in thefe creatures,
which we call the head, and which when we eat them we throw
away, was not only the head, but, for the greatefl: part, the belly of
the Shrimp, whence I concluded that there its llomach might be
found.
( 270 )
The firft thing I examined was the mouth of the Shrimp, which
I found on all fides pi-ovided with various organs, and each of thefc
again fiirnilhcd with many weapons, the w^hole of which feemed
contrived for the purpofe of catching the Shrimp's prey, and con-
veying it to the mouth.
Upon opening the mouth 1 law that it had on each fide a tooth :
the fore part of this tooth, to be ufed in biting, was not fmooth or
even, but made with indentings or notches ; and, upon applying one
tooth to the other, I found that the rifing parts in one tooth moll ex-
aAlv fitted the cavites or notches in the other. Thefe teeth in the
fore parts or edges were a little broader or thicker and of a yellow-
ifli colour, but the lower ends of them were white.
I caufcd a drawing to be made of the Shrimp's tooth, as feen by
the microfcope, and this is fliewn o.t fig, 3 1, KLjNINO, in which
figure the letters KLM denote that part of the tooth chiefly ufed
in biting.
Coming to the fiomach, which I took out of the bodies of feveral
Shrimps and laid open, I law that Ibme of the animals had fed on
linall filhcs, mixed with minute Shrimps bitten in pieces, and in
one Shrimp I found fofne large fragments of another Shrimp which
had been of a middling fize, from whence it appeared plain to me,
that a Shrimp can open its mouth much wider than I had before
imagined.
The fiomachs of other Shrimps were empty ; many others I faw
containing a great quantity of thin pai'ticles, which I deemed to be
fmall bones, \\'liich had been part of the fins of fome fmall filhes,
and alio fome of the organs of other Shrimps ground to pieces in
the mouth.
Thefe thin oblong particles I have mentioned, when vicM^ed by
the microfcope, exhibited the fame appearance as the fragments or
lliavings of one's beard viewed with the naked eye, with this dif-
ference only, that thefe particles terminated in a point at one end.
I alio law a particle, one fide of which was armed with teeth notched
( 271 )
like a law ; and I alfo law the claws or pincers ot a young crab,
which had been no largei- than a grain of land.
The Itomachs of others were filled with fragments of fmall bones
from the fpine of minute lillies, appearing like the back bones and
tails of haddocks. I like wife law a fmall bone of a lliape and make
diflerent from any I had ever before feen in fillies.
■ 1 alfo faw in the llomachs of many Shrimps, but not in equal
quantities in all, fmall fliells, in fliape fimilar to thofe llaells which
are found in the greatell quantities on our coall:s, nor did I find
many fragments of fuch fhells, whence I concluded that, about the
beginning of September (for it was about that time thefe obferva-
tions were entered upon) many of the fmall flicU-filli, newly pro-
duced from the parent, had been caught by the Shrimps, and their
fhells broken by their teeth, in order to pick out the young filhes
from the fliells and ufe them for food.
Many of thefe minute fliells were no bigger than large grains of
fand, and I was moreover well alTured that all thofe fliells which I
took out of the llomachs of the Shrimps had been but a few days
brought forth by the parents, becaufe many of thofe fliells were
quite tranfparent, others of them were in part about their outer
edges rather obfcure, by reafon, as I imagined, that they had had
an addition in growth fince the filhes were brought forth.
I caufed a drawing to be made of one of thefe minute fliells, but
which was one of the largell of thofe I had extradled ; and, at fg.
35, this fliell is fliewn of the fame fize as it appeared to the limner
by the naked eye. Fig. 36. P Q R S, is the fame fliell feen through
the microfcope : the letters P Q R T fliew that part of it which ap-
peared bright and tranfparent, fo that all without the letters PQRT
which was not tranfparent, was added to the fliell by growth, after
it was feparated from the parent.
In fome of the Shrimps' llomachs I found fome exceeding minute
fliells, which, on account of their round figure, I called fnails, and
which were not larger than a large grain of fand ; and to fliew the
( 272 )
pretty fliape of thefe fliells, I thought it would not be amifs to give
a drawing of one of them : this is to be feen at jig. 37, ABC, as
viewed through the microfcope.
I next examined the intertines of the Shrimp, to fee whetlier I
could there difcoA'er any of thofe fmall bones or fliells, but finding
none, I began to confukr that, perhaps, when Shrimps have kept
thofe Hiells, or other hard fubftances, which cannot be digelled or
ground to pieces by the a6tion of the ftomach, fo long as that all
the niitrive particles which can pafs into the inteftines are extract-
ed, w hether they do not throw up the remainder, and void it at
their mouths.
The paflage out of the flomach was provided with certain organs,
like teeth, for the purpofe (as I think) of grinding the food a fe-
cond time, before tranfmitting it to the inteftines.
I have often refle6led on the great number of eggs which Shrimps
are accustomed to carry, faftened to thofe limbs or organs placed on
the lower parts of their bodies, and which are commonly called their
feet ; and efpecially when I conlldered that thofe eggs, w^hich arc
by fome means fixed on that part, did not feem to grow any larger,
and that all thofe which I faw were of the fame fize, from whence
I could not fatisfy myfelf in the belief that thofe eggs had been
formed in that place.
Hereupon I began to difleA the belly of the Shrimp, which is in
that part commonly thought to be its head, and then I faw that the
eggs were chiefly placed there, and the remainder of them next the
back, where the body of the Shrimp is thickeft.
The eggs which I took out of the bodies of Shrimps were not of
equal fize in all, but fome larger than others : and beween thofe
eggs which had been put forth from the Shrimp's body, and were
fixed to the lower part of the body, and tlie largeft of thofe which
ftill remained within the body, I could not difcover any ditference
in point of fize.
( 273 )
It was to me a pleafant fpedacle to view the eggs, as they lay in
the bodies of the Shrimps, for every one of them had in the middle
of it a fmall round bright fpot, in like manner as if we Mere to fee
with the naked eye, a tranfparent egg, with a Itill more tranfparent
yolk in it.
Having made thefe difcoveries, I concluded for a certainty, that
when the eggs within the Shrimp's body are come to their full lize,
that they are foon afterwards emitted out of the body, and, by the
Shrimp itfelf, fixed to thofe organs commonly called by us its feet,
and that they are alfo placed as dole as polhble to the animal's
body, fo as to be no impediment to thofe organs in the performance
of their ufual functions. But though each of thefe organs is fur-
nilhed with a number of ftill fmaller organs, yet all taken together
would not be fufficient to hold fall; and fecure the great number of
eggs with which they are loaded, nor could thefe eggs be fecurely
fallened, unlefs each egg had a kind of tiring or ligament, by means
ot which they are all fattened together, like a chain or llring of
beads.
Fig. 38, DEF, reprefents a very fmall portion of thefe e^gs,
which were dried and placed before the microlcope after being taken
out of the body of the Shrimp.
Fig. 39, GHIKL, reprefents the receptacle of the egg, of its
natural fize, taken out of the Shrimp : the letters G H K L indicate
that part which was in what is called the Shrimp's head, and H I K
that part which lay in or next to the folid part of the Shrimp's
body. Now, when thefe eggs increafe in lize, then that part,
marked GL, in part furrounds the llomach of the Shrimp, and, iu
proportion to the quantity of food in the ftomach, it either extends
farther or is reprelfed by the diftention of the llomach.
I have alfo obferved that, when dillected, fome Shrimps whofe
eggs which were fixed on the outfide of their bodies had arrived at that
maturity that, I judged, they would produce young minute Shrimps
in a few days, within the body of the fame Shrimp I could perceive
Vol. II. INI m
( 274 ,)
a great number of eggs, which I thought were grown to that fizc,
that within a few days they would be emitted from the body and
placed on the outfide of the Shrimp.
As we now fee that thofe Shrimps, which are taken in the fea near
our coalls, do falien their eggs to the lower parts of their bodies until
the young are able to ilfue forth and fwim about (whence it is, that
Slu-imps newly hatched can, in ftormy weather, retire to the deeper
water, and avoid the agitation or ground fwells of the fea upon the
fliore") ; on the contrary, among thofe Shrimps which are caught in
the inland fea, round about Amlterdam, few or none are found bear-
ing their eggs about them in that manner : liereupon it feemed pro-
bable to me, upon refled;ion, that perhaps thefe lall mentioned
Shrimps, when their eggs are grown to a lize to be excluded from
their bodies, refort to the creeks and fliallow^s of that fea, where thej
can find a fufficient quantity of leaves and rufhes to which they can
fatten their eggs.
In the month of Rlay I examined the bodies of fixty-four Shrimps,
forty-nine of ^^ hich had eggs fixed to the lower parts of their bodies,
and the your.g fhrimps in thefe eggs were fbmc of them more per-
fectly formed than others, and the darker the colour of the eggs the
more full grown were the young within: of the remaining fifteen,
I found eggs w'ithin the bodies of twelve.
I oftentimes repeated thefe my refearches, and always with nearly
the fame fuccefs. And when I met with Shi'imps which had no
eggs fall:ened to the outfides of their bodies, I began to confidcr
whether or no thofe Shrimps might not have fattened their eggs to
leaves, litter, or other fubflances at the bottom of the fea.
I afterwards examined many parts of the inteftines of this crea-
ture, which were formed fo wonderfully, and with lb much art,
that to attempt a particular defcription of them would be only lofing
time and labour. In a word, if we could place all thofe organs be-
fore the microfcope, make drawings of them, and could alTign to
each part its ufe, we might cry out, What depth of wifdom is here!
( 275 )
what hidden wonders in fo contemptible an animal ! and, how lit-
tle is it that we know !
The mouth of the Shrimp is not, in my judgment, calculated to
catch fhlies, but only to pick up its food, but that defect is well
fupplied by two organs placed on the fore part of the Shrimp's
body, and which may be compared to arms and hands ; thefe are
furnifhed with many joints, and at the extremities have each of
them two nails or claws, the larger of which is moveable, and the
fmaller fixed and immoveable : by the help of thefe claws the
Shrimp can, in my opinion, catch and hold fall many minute fifties,
and alfo convey them to its mouth, there to be ground fmaller by
the teeth.
I have given a reprefentation of thefe claws, as feen by the mi-
crofcope: fig. 40, MNOPQRST, is one of them, which I may
call the Shrimp's hand. The part denoted by the letters N O P is
the nail, which I think is immoveable, and only ferves the Shrimp
to pierce into the bodies of fuch fmall fifhes as it catches. P Q is a
ftiarp bony part, which ferves to hold the prey more firmly, and is
covered with fliort hairs, fome of which extend beyond the edges of
it. Q R S is the larger claw, which the Shrimp can open and fhut
at pleafure, and it is liollowed on the infide, the more firmly to keep
its hold. Fig. 41, VWXY, reprefents the fame organ, which I
call tlie Slirimp's hand, in fuch a pofition that the larger claw is
clofcd : VW reprefents the fmaller claw, and YXY the larger,
which, when clofed, reaches a little beyond the fmaller, as may be
feen at Y.-
I have fometimes feen thele claws broken, and in a fiate of de-
cay at the points, caufcd, as I fuppofe, by their firuggling ^^■it]l
filhes too rtrong for thcni.
From the view of thefe ckiws in the Shrimp I was able to fatisfy
myfclf as to the ufe of thole very llrong claws which we obfervc
crabs to be provided with, and w hich, I think, are not intended
M m 2
( 276 )
merely for catching their prey, but alfo for grinding or breaking it
into finall pieces, before it is taken into the mouth.
I have obferved Shrimps to have eggs on their bodies during the
whole of the fummer, but in the month of November no eggs were
to be found on them. But when we confider, that all the time
Shrimps carry eggs on the outfidcs of their bodies, other eggs are
forming within them, who can pretend to fay how many times in
a year Shrimps bring forth young ?
I never was able to fatisfy myfelf that I had found a Shrimp of
the male fex ; and all the pains I could take in the fearch more and
more convinced me that there are no males among thefe creatures,
herein refembling thofe fmall flies which I have difcovered, and de-
fcribed in another place.
Thefe things being confidered, namely, that all Shrimps indiffe-
rently do bring forth young, and that many times in the year, and
every time in very great quantities : thefe confiderations, I fay,
fully folve what was once with me a difficulty, in regard to the great
quantities of Shrimps which are continually brought forfale, info-
much that many perfons in our large towns make a- living by that
traffic, befides the people who are employed in taking the Shrimps
in the fea.
Of the Salts contained in Pepper, ayid in Tea, ivith the Author" s
reafonings thereon : the Salts found in Cantharides defcribed.
1 HAVE often reflected on the nature of Pepper, and particularly
what might be the reafons that the particles of Pepper excite fuch
a pungent fenfation in the mouth, when the fame, taken into the
ftomach or intellines, do not caufe any irritation, fo as to promote
an evacuation.
I at one time thought, on looking at the internal or mealy part
of Pepper, that the particles compoling it might many of them be
very fliarp pointed, and thereby produce that kind of pricking on
the tongue, vs^hich many call heat or burning. But I afterwards
rejedled this opinion, becaufe, upon contemplating a great number
of thefe particles, I faw they were all of different Ihapes.
I made a drawing, from the microfcope, of five of thefe parti-
cles, many of which together conftitute one grain of Pepper, and
thefe are ftiewn in Plate XIX, at Jig. 1 , A. ISIany of thefe parti-
cles are, indeed, very long and lliarp pointed, which I never ob-
ferved in any other feed I have examined, for the mealy particles in
other feeds are more of a globular form. Befides being of an ob-
long fliape, the particles of Pepper are flat on fome of the fides and
irregular on others, but in fuch manner that there are no cavities
between the particles, for otherwife each grain of Pepper, when
come to maturity, would not be a folid body.
But what is very remarkable, thefe fhiall particles of Pepper,
when laid in water, do neither fwell nor become foft, like the
mealy fubllance of wheat, rye, peafe, beans, and the like, but
preferve their flaape (at leall as far as I have been able to obferve).
( 278 )
ISIany of thefe particles of Pepper arc tranfparent like glafs, and
others of them may be fccn to be compofed of il'dl fmaller particles.
Having examined the parts of common Pepper, I took fome of
that ^vhich is called long Pepper, and bccaufe I believe that many
perlbns are unacquainted with this kind of Pepper, I have caufed a
drawing to be made of it, which is reprefented at Jig. 2, BC DE,
in which B C is the tlalk, and C D E the fruit or Pepper itfelf.
Upon cutting open this long Pepper, I perceived it was not a
fingle feed of Pepper, but what is called a pericarpium, that is, a
cafe or flicU containing many feeds, and in this lliell were contained
above an hundred fmall grains of Pepper,
Several of tliefe fmall grains, each of which is contained in ar
particular fkin or covering clofely adhering to it, I took out entire,
and held them in my mouth, in order that by the moillure the co-
verings or Ikins inclofing them might be foftened, and I might the
eafier difcover the mealy fubflance of which thefe fmall grains of
Pepper are compofed. In doing this I found that the grains, though
not broken, excited as flrong a fenfation on my tongue as if they had
been pounded Pepper, whence I concluded that the mealy fubllance
of thefe grains, which in fize and fliape agreed with our common
Pepper, did not excite that fenfation by the acute particles in them,
which I have faid are to be difcovered by the micro fcope, but rather
by fome faline particles exciting on our tongues that kind of prick-
ing which is called heat.
I therefore took fome of this long Pepper, which I put in clean
paper and pounded it on an anvil : I then put it into a new glafs
vellel, pouring rain water on it till it was covered to about the third
part of an inch ; after this water had flood about two hours I poured
it off, but it being evening I let the water ftand all night ; the next
morning I faw, in the place where the water was motl evaporated
an incredible number of laline particles, many of which Mere almoft
twice as long as broad, but one fide always longer than the other,
both fides parallel, and the two lliortcr tides Hoped from the
( 279 )
longer, as reprefented at Jig. 3, F. All thefe faline particles were
exceedingly thin. There were many others formed in the fame
manner, but rather narrower, as at fig. 4, G : I alfo fliw many fa-
line particles in which I could not difcover any acute angles, ns fig.
5, H; but the greateft number of particles, being more than all the
reft put together, M'ere broad in the middle and drawing to points
at the fends, as reprefented at Jig. 6, I. Thefe laft particles were
of various lizes, and fome fo minute as to be fcarcely diftinguifh-
able.
After the water had flood a whole day and night, I faw fome
faline particles collected together in an irregular form, fo that they
had two, three, or more points at the extremities, as appears at^^,
7, K, which I concluded was caufed by fome of the particles ad-
hering together.
From thefe obfervations I concluded that the heat which we feel
in our tongues from Pepper, is nothing but the falts or faline parti-
cles pairing from the Pepper to the tongue, and the fliarp points of
which fo prick the tongue as to excite the fenfation we call heat, as
before mentioned ; but when thefe faline particles by degrees coa-
gixlate, as I have before obferved, and get into the ftomach and in-
teftines, they may, by fuch coagulation, fo alter their fliape as to be
prevented exerting fuch a ftimulating power as to caufe evacuation,
or at leaft thefe particles may alter their figure ; to which we may
add that the juices in the throat, ftomach, and bowels, may promote
fuch coagulation, or other difpofition of the pungent faline particles,
as to prevent their irritating the ftomach or inteftincs, if they are
not taken in too great a quantity.
To fatisfy myfelf farther on this fubjecl, I took a new glafs and
put into it fome long Pepper, and, by applying fire to it, I drew off
oil from it ; the oil, or fpirit, which was firft driven oft' by the fire,
I often examined, but faw nothing in it worthy of note; the oil that
came off laft, being heavier, funk to the bottom, but iu this I re-
marked nothing particular.
"( 230 )
I afterwards mixed water with the oil, and b}' the fire I mixed the
oil and water as much together as I was able, but in this I could
obfervc nothing except a few falinc particles, like thofe reprefented
at ^o". 0, I ; but thcfe I could not well dirtinguiih on account of the
oil, the water being evaporated. I alfo faw in the oil various par-
ticles, which I thought were falts irregularly joined together.
Upon the caput mortuum, or fubftance left behind by the 'fire, I
poured fome clean rain water, and let it ftand for fome hours, that
the fixed falts it contained might be drawn ofF by the water ; after
this I poured off the water as clear as I could and expofed it to the
air in my clofet, the weather being calm and the funfl^ining bright,
but the water did not at firil evaporate : but, after llanding two
days and nights, I faw a great number of faline particles fwimming
in the water, like thofe pi6lured 3.tjjg. 5, I. I alfo faw many fmall
flat particles of fix fides floating about, fome of which were fo fmall
that I could not difiinguifh the Ihapes of their fides without great
attention. I concluded that this liquor was, for the moll part, com-
pofed of fixed fait; therefore I expoled it to fome greater degree of
heat, and then I faw, as I may fay, the whole of it converted into
irregular faline particles, which were as tranfparent as glafs, and in
fuch numbers that they looked like a heap of fand.
Upon breathing my warm breath on this newly formed fait it
again changed into a tranfparent fluid liquor.
From thefe obfervations I neceflarily concluded that there was but
little volatile fait in Pepper, becaufe I obferved few particles of tliat
fiDrt in it.
After this I took common white Pepper, becaufe I think that there
is no other ditFerence between M-hite and black Pepper, than that '
the outward Ikin or fliell, which is fl:ripped olF the former, is left on
the latter.
This Pepper I alfo put into paper and pounded it into fmall parts,^
and infufed it in water. After the water had flood about two hours
I poured it ofi' as clear as I could, and in the evening placed it in my
( 281 )
clofet : the next morning I examined it, and with great pleafure I faw
in it all the fame kinds of faline particles as I have pictured at F G
H I, thefe I could difcern moft diftinftly, and in gi-eat numbers,
yet much fewer than thofe I had before feen in the long Pepper,
though the quantities of white and long Pepper, and of water, in
which I had infufed them both, were nearly equal.
I alfo drew off the oil and fpirit from white Pepper, but I could
fee nothing in the oil except a few particles, which I thought to be
falts, in the thinner oil or fpirit I faw fome faline particles, the
fame as reprefented at jig. 0, I. Thefe were fo fmall, and lb hid
by the oil, that they could not be dillinguilhed without great at-
tention.
Farther, I poured fair rain water on the caput mortuum, or folid
fubllance left of this Pepper, and after it had flood for fome hours,
I poured it off; and when the greater part was evaporated, I faw
fome faline particles lying in it which had fix fides like an equila-
teral triangle, with the three angles or points a little cut off, as
fhewn at fig. 8, L. Others had fix equal fides : there were alfo
fome exceeding thin quadrangular figures, as at jig. g, M, and
fome parallelograms, as at fig. lo, N, which were wonderfully
thin. Alfo many fmall particles like thofe pictured at fig. 6, I^
fome of which were blunt at one end, and fliarp pointed at the
other. I faw alfo various particles, at the extremities of which I
could not difcover any point. All thefe faline particles were fur-
rounded with an exceeding thin tranfparent liquor, which upon the
leall heat being applied, was changed into irregular faline particles,
which caufed all the before mentioned particles to alter their exa6t
Ihape. But with the fame eafe as this liquor was converted into
falls, it was again refolved into a fluid only by breathing upon it
twice.
A gentleman of my acquaintance received from the Eaft Indies,
among other prefents, a fmall jar filled with the falts extraded from
Vol. II. N n
( 282 )
Tea, which he confidered as a prefent remedy againft fevers. A
parcel of this he gave to me, which having left for fome hours on a
Iheet of paper, I found it foft, as if it was going to melt away,
therefore I put it into a new glafs, and poured rain water upon it, in
order to diilblve it entirely.
I expofed three different portions of this water to the air, that
part of it might evaporate, and by this means fome particles of falts
became vifible, and after a few hours were expired, I faw a great
number of particles fwimming in the water, which were almoll all of
the fame fhape, namely, oblong, and terminating obliquely at the
extremities, as at fig. 11,0. But thefe figures were not flat, but
fomewhat rifmg in the middle in a fort of ridge, and fl:iarp at the
ends, and tranfparent like cryilals. Others of thefe faline particles
were not fo perfed, becaufe one half of them was fomething
broader than the other half, as is fliewn atj%. 12, P.
After this water had flood about two days, I faw the faline par-
ticles in the place where the water was not entirely evaporated to
be fomewhat increafed in fize, but retaining their former Ihape.
1 faw alfo in other parts of the liquor not evaporated, a number
of fmall roundifli particles, in which I could not diftinguifli any ex-
ad fliape, though I viewed them very narrowly and with a very
deep magnifier, aiid befides them an incredible number of wonder-
fully minute particles, the fhapes of which I was flill lefs able to
diftinguifli : thefe laft particles I concluded to be fo minute, that a
thoufand miUions of them together would not equal a large grain
of fand. However, upon ufing my fharpeft and greateft magnify-
ing microfcopes, I faw the faline particles, which, as I have faid,
appeared round to me, to be, for the moft part, of fix fides, and fome
few of them three. And among the minute particles that I law
in fuch incredible numbers, I was able to diftinguifli many of
them to be of the fliape rcprefentcd at fig. 3, F. Others were fo
fmall, that I could not with certainty aftign any particular figure
to them.
( 283 )
After this liquor had Hood more than two days expofed to the air
in my lludy, the weather being very warm, with a dry eaft wind,
and about half the moifture remained, I concluded that it then
moftly confirted of falts, which were too foft to coagulate, I there-
fore applied it to a moderate heat, and then I faw an incredible
number of faline particles formed in it, many of which were of fix,
and others of four fides. But whereas our common fait, dilfblved
in water, when it again forms itfelf into falts, affumes an exaft qua-
drilateral figure, or if a little of an oblong fhape of four fides, yet
each angle is always a right angle, or contains ninety degrees, as
far as the eye can judge ; on the contrary, thofe faline particles I
am now defcribing, were not only compofed of irregular angles
and fides, but their fides did rife up in a pyramidical form, like our
common fait, fo that they appeared to me like irregular quadrila-
teral cubes. But I muft needs fay, tliat none of the faline parti-
cles which I ever faw extrafted from plants of any kind, appeared
fo regularly formed in their cryftallization, or coagulation, as the
falts produced from the firft infufion of Tea, and which are repre-
fentedat/o-. ii,0, and^^. 12, P.
After this, I took a parcel of my bell Tea, which I put into a
new glafs, and, by degrees, applied to it fo firong a fire that the
glafs was red hot, colleding, with all the care I could, the fpirit,
oil, and volatile fait, which proceeded from it. I then obfervcd
that the oil, as foon as it was cooled, was not only very thick, but
could not be rendered liquid, fave by heat. Upon examining this •
oil by the microfcope, I thought that its tenacity was occafioncd by
the extraordinary great number of volatile falts it contained, and
the number of thefe falts was fo inconceivable that it is impoflible
to give a true idea of them, fo as to conceive that fuch a fmall
quantity of Tea could produce fo many particles of volatile fait.
All thefe faline particles were of the fame fhape, that is, very long
and pointed at both ends ; thefe are reprefented at Jig. 13, Q.
N n 2
( 284 )
I afterwards endeavoured, for my farther fatisfa^lion, to difcover,
if poffible, how many faUne particles would be produced from a
lingle leaf of Tea, but having reckoned up only a part of the vo-
latile falts contained in one leaf, I forbore any farther obfervations,
becaufe the number I had already reckoned up was fo great that I
durft not publifli it, as I had purpofed to do. And, indeed, many
perfons could not believe that the leaf itfelf could be divided into fo
many parts, vilible by the microfcope, as I faw volatile faline par-
ticles produced from one lingle leaf.
Moreover, I took the caput mortuum, cinder, or aflies of Tea,
on which I poured clear rain water, in order to extract the fixed
fait it might contain. After this water had flood on it one, two,
and fome of it three days, I poured it off as clear as poffible, and ex-
pofed it to the air to evaporate : I then obferved in it many parti-
cles of what I before mentioned to be volatile fait ; thefe were not
only covered, as it were, with a watery moiflure, but many of them
I faw lying in the water, fo that 1 was convinced they were particles
of volatile fait, which had been fo clofely united to other falts, and
to the caput mortuuum or alhes, that the fire I had applied had not
been ftifficient to expel all thofe particles of volatile fait.
As I concluded that the watery moiflure which did not evaporate,
and in which the before named faline particles lay, was nothing
but a parcel of falts, though I could not diftinguifli their figures ; I
applied fome heat to it, and I immediately perceived that, in fad,
the moifture was for the moft part fait, for it concreted in irregular
faline particles, and in fuch numbers that the fubftance became white.
But foon after it again changed into a fluid and tranfparent liquid,
like water. But after I had fuffered this liquid to fiand a little
longer, 1 perceived various faline particles of fix fides formed in it,
which are reprefented at fig. 14, R. Among thefe, many were fo
fmall that they almoft efcaped the fight, even though affifted by my
very befl microfcopes. I alfo faw fome few exceeding minute faline
particles, with figures of four fides.
( 285 )
After this I, at two feveral times, examined the water which had
Hood a Uttle longer on the caput mortuum, or afhes, and then I law
a greater number of the particles with fix fides : I alfo faw a few
particles like thofe reprefented at Jig. 11,0.
Moreover, I put a parcel of Tea in cold clear rain water, and af-
terwards fome Tea in hot water, in the fame manner as it is com-
monly made for drinking ; this infufion of Tea I fuffered to evapo-
rate in part, and, in various obfervations upon it, I always found that
there were formed in it manyfaline particles, coagulated or concreted
together, as reprefented at Jig. 13, Q, and Jig 15, S ; thefe were of
various lizes, and many of them fo miniite as to be almoft invifible.
Thefe faline particles could not at firil be eafily diftinguiflied, by
reafon of the multitudes of fmall particles which were floating in
the fluids, in fuch numbers that they made the water thick or
muddy, fo that it feemed to me impofllble that hot water could, in
fo flioi-t a time, extra6t fuch a number of faline particles from the
Tea : and I formed an opinion that the many faline particles in Tea
w^ere of fuch a nature and property as to coagulate, or rather con-
denfe, the particles in water, which we call watery particles, and
that moll of thofe wonderfully minute particles, which I have faid
rendered the water turbid or muddy, did not derive their origin from
the Tea, but from the water itfelf. Whence I concluded that all
the virtue or efled: of Tea, when taken into our bodies, conlifls in
this, that it occalions a great coagulation or condenfation of the
thick particles of the chyle in the llomach and intellines ; whence
the other particles or fubflance of the chyle, which palles to the
nouriihment of our bodies, being rendered very fluid, the blood may
be in a fliort time diluted or rendered thinner, by which diluting or
thinning of the blood we are often relieved from pain in the head,
and our whole body refrefhed.
I might here add my fentiments as to the reafons why drinking
Tea is fo very falubrious to many people, though the ufe of it docs
not agree with fome few. But, as thefe my fentiments might not
( 280 )
be plcafihg to fome, I have omitted them, and the rather becaufr
1 meet with men, whole wliole aim is to find fault AVith what 1
advance.
To thele oblervations i will add what I have obferved refpecling
Spanifli flies, or Cantharidcs. I have examined thefe Flies by the mi-
crolcope, and fo\md that their feet were covered with many won-
derfully fliarp particles; but, as thefe are feen on common flies, I
could not think that thefe particles could produce fuch an irritation
that when Cantharides are mixed with any ointment, and laid on
the body in the fliape of a plaller, they raife a blifter on the part.
I put, therefore, fome Cantharides into a clean paper, and, hav-
ing pounded them, I poured clear rain water on them. Some of
this water I expofed to the air, that the faline particles in it might
coagulate, and, after about half an hour had elapfcd, I faw a very
great number of faline particles, which were three times longer than
broad, though I could not difcover their exaft fliape.
I then took a larger quantity of water, and let it fl:and a whole
night, to fee whether thereby the faline particles would concrete in
larger figures. In this time almoft all the water was evaporated,
and the faline particles were fo concreted together, that I could very
dirtinAly difcover the fliapes of each of them. Thefe particles lay
in fuch numbers that they made the remainder of the liquid appear
white ; and it was a very pleafant fpeftacle to me, to fee fo many
particles lying together of an uniform fliape.
Many of thefe were fquare at one extremit}^ making two right
angles ; and at the other end two oblique fides, making an acute
angle, as reprefented at fig. l6, T: others of them were oblique
at one end, and the other fliaped like the preceding figure, as is
fhewn at J?o-. 1 7, Y. Some few of thefe faline particles had the two
ends oblique, as f(g. 18, W, and a few others two fides oblique,
but one fide rather longer than the other, as/g-. ig, X. The longefi
( 287 )
(ides of all thefe particles were parallel to each other, and the par-
ticles were very thick in proportion to their length.
Moreover, by the help of fire I drew off the oil and fpirit from
Cantharides, but neither in the fpirit nor the oil could I dilcover any
faline particles. After this I mixed fome clear rain water with the
fpirit and oil, and fliaking them together, to promote the coagula-
tion of the falts, I fawmany laline particles, which at firll appeared
flat and thin, and rounded at the extremities, but the longeli fides
of them turned or rolled themfelves together, as is Ihewn at jig.
20, Y.
After this, I faw various faline particles floating in the fame fpi-
rit and oil, of the fame fliape with the former but much fmaller, at
the fame time I faw fome faline particles of fix fides, but fo minute
that they almoft efcaped the fight. I likewife perceived a very great
quantity of particles, which I deemed to be lalts, but by reafon of
their extreme minutenef^ I could not, with all my attention, aflign
any particular figures to them.
The caput mortuum or cinder left of the Cantharides, I alfo in-
fufed in clear rain water, in order to difcover the fixed lalts it might
contain ; and, after the water had ftood on it about two days, I fuf-
fered part of it to evaporate, and then I difcovered a great quantity
of faline particles, the fliapes of which I could not diftinguifli by
reafon of their minutenels. But when almoft all the water was eva-
porated, I faw a few faline particles of a regular fquare fliape and
exceeding thin, and among them a few whole fides rofe up in the
fliape of a pyramid, like our common fait, and alfov fome oblong
figures of four fides, fome of them exceedingly thin ; likewife fome
particles pointed at each end, as is fliewn at Jig. 21, Z, and fome .
of thefe lali: feemed, as it were, divided or notched at the other ex-
tremity, and with two points, as is reprefented at Jig. 22, a.
The little moifture in which thefe very minute particles lay, eva-
porated on the leaft heat being applied, and then fome oblong and
( 28S )
rregulai* particles appeared coagulated. But when I breathed upon
them two or three times they again diflolved mto a tranfparent
liquor.
I have mentioned, as my opinion, that there is no difference be-
tween ■white and black Pepper, except that the white is black Pep-
per ftripped of its Ikin. And, to prove this by experiment, I took
half a pound, or eight ounces, of black Pepper, which, in about
three quarters of an hour, I lli'ipped of all the (hells or hulks, and
was thereby confirmed in my opinion, for this Pepper might have been
fold for "white Pepper. From whence it appeared to me that white
Pepper is better than black, not only becaufe it is largeft and ripeft,
but alfo becaufe there is little virtue in the hulks or Ihells of black
Pepper, and alfo becaufe among the black there are found many
parts which may be taken for grains of Pepper, when, in facft, they
are only unripe grains, or only hulks of Pepper, When I had thus
converted my black Pepper into white, I weighed it again, and
found I had not fo much as five ounces, fo that out of eight ounces
I had loll more than three, though I mull confefs I had not been
very careful in the operation.
Of the young Plant difcernible in Seeds, and on the Blo//oms,
Fruit, a?id young ffbod, in the Buds of Fruit Trees.
x\.FTER examining the young plant in Wheat, I turned my at-
tention to that in Rye, and after ftripping off the external Ikin or
hufk from the feed, I took out the young plant, and placed it be-
fore the mifcrofcope.
Plate XIX. Jig. 23, ABCD, is the young plant in a grain of
Rye, as feen by the microfcope, A a B D, are the parts from which
the roots and Hems, or ftraws, will proceed ; C is the top of the firfl:
leaves in the young plant. Upon cutting this young plant tranf-
verfely at the end next A, I could only perceive the beginning of
one flalk or llem cut acrofs ; but when I cut a little farther towards
B or D, till I came to a, I perceived two ftems, and ll:ill farther to
B D, I faw the beginnings of three flalks or ftems ; and though I
could not at firll fee more than the beginnings of three llems or
flalks, yet I was very well convinced in my own mind, that every
grain of Rve has in it the origin of four ftalks or Hems; for A a,
are two principles or rudiments of the largeft young ftalks or ftems,
and B and D are two other principles or beginnings : at length,
after difle^ling tranfverfely many grains of Rye, I perceived that I
had cut through four feveral trunks, ftems, or ftalks at one cutting.
All thefe young plants are placed in a kind of meal, which is not
fo white as the reft of the fubftance of the Rye.
I have not given drawings of thefe young ftems or ftalks cut
tranfverfely in the grains of Rye, partly, becaufe I could not place
them before the limner's view fo diftinc^ly as in Wheat, and alfo
Vol. II. O o
( 290 )
becaufe there was very little difference between thofe in the Rye
and in the Wheat, except that thofe in Rye were much fmaller.
I alfo examined the feeds of Barley, and took from thence the
young plant with its leaves. But becaufe I perceived very little
difference between them and thofe in the grains of Wheat and Rye,
I did not think it neceffary to give drawings of them.
But what is worthy of remark in Barley is, that in every grain
there are to be feen the rudiments or beginnings of five dillind
plants, therefore I have caufed a drawing to be made of them, as
they appear at one cutting of the feed tranfverfely.
Fig. 24, A B C D E F G, is a fmall piece of a grain of Barley cut
tranfverfely near the end of the feed, where the origin of the young
plant is formed, in which may very plainly be feen, a tranfverfe
fedion of five feveral particles of an oval fliape, in each of
which, the veffels compofmg them may be diftinguiflied. The
reafon why thefe young beginnings of plants appear oval and not
perfeAly round, I take to arife from the evaporation of the moif-
ture, as well in the plants, as in the mealy fubliance furrounding
them ; for we mull: confider, that the external part of the feed in
drying will contrad itfelf, and that when it is afterwards moiftened
with water, it will, in a Ihort time, again extend itfelf, and then
the plants, inllead of an oval, will affume a round figure.
Thefe young plants are placed in a very fmall quantity of mealy
fubftance of a darker colour, and not compofed of fuch tranfparent
globules as the reft of the meal of which the Barley confifts. This
dark meal is placed between G A B C D E, iind betw een E F G is
the mealy part, which for the moft part compofes the fubfi:ance of_
the Barley ; and though this dark mealy fubliance may here feem
to be in great abundance, yet it mull be obferved, that this does
not extend farther in the Barley, rifing no higher, (in a Hoping di-
redion), than where the young plants extend.
I afterwards examined Oats, and found that each feed contained
in it the beginning, or firft rudiments, of young plants, and the be-
( 201 )
gainings of leaves ; and that the young plants were three in num-
ber in this feed.
Now as we fee, that the principle of vegetation, or young plant,
in every one of the before mentioned feeds, is capable of producing
two, three, four, or five llioots or ftems, according to the fertility
of the earth in which they are fown, we are not to wonder, that
from fingle grains of Wheat, Rye, Barley, or Oats, fuch numbers
of flioots or flraws are produced, as we obferve.'
Among many other feeds which I examined, I obferved a re-
markable variation in the feed of Buck-wheat, and in my endea-
vours to difleft this feed, I was obliged firll to take off the hard
fhell, and then fleep the feed in water for feveral hours ; for the
leaves of the young plant were fo intimately conne6ted with the
mealy fubftance of the feed, that, until they had been thoroughly
wetted, it was impoflible to feparate them. When I had taken out
the young plant, I found the leaves fo twifted one among another,
that it was not without great difficulty, I could fpread them apart
by fmall pins, fo as to be diftin6lly feen, for thefe leaves were ex-
tremely weak and tender to handle.
Having placed thefe leaves before the microfcope, I difcovered in
them a vaft number of veflels, (which, in a full grown leaf, we
fhould call fibres or ribs, though in fad; they are nothing but vef-
fels), appearing like what we fee by the naked eye in vine leaves.
But whereas, in the leaves of the young plants of Wheat, Rve,
Barley, and Oats, the veflels run lengthwife along the flem, in like
manner as the veflels do in thofe leaves when full grown ; on the
contrary, the vefl'els in the leaves of the young plant in Buck-
wheat are fpread all over the leaves, in like manner as may be
feen in the leaf of that plant when come to its full growth. I
fhould have given a drawing of this young plant, as feen by the
microfcope, were it not that it would have taken up too much room
on the paper ; for, (contrary to other young plants that occupy
but a fmall part of the feed) thefe young plants fpread all over the
O 02
( 292 )
fted, and the leaves are extended as far as the outer Ihell or hult
of the Buck-wheat. I have, however, given a drawing of the
plant fo far magnified,- as to Ihcw it dittindtly ; and hkewife a fmall
llice of the feed cut tranfverfel} , in order to fliew in w hat manner
the young plant is placed in this feed.
Fig. 25, H KLM, is the young plant taken out of the feed of
Buck- wheat, and feparated from the mealy fubllancc in which it lay,
and in which, as much as polfible, the feveral twills or folds are laid
open, and the whole (as I faid before) magnified juft enough to
Ihew the leaves and the future plant diftinAly. ,
II K L, is a large and very thin leaf, within \n hich lies another
leaf much fmaller and thinner, which it is very difficult to dillin-
guilh. This fmall leaf, I feparated a little from the larger one,
and let it dry in that pofition, that the hmner might the better dif-
tinguifh it; this is fhewn at letter K, and the part from which the
root and ftem will proceed is noted by the letter M.
Another of thefe feeds I feparated from the hard fliell and mem-
brane inclofing it, and cut it tranfverfely near the point where
the root of the young plant is fituated : this I placed before the mi-
crofcope, and caufed a drawing to be made of it to fliew in what a
wonderful manner this young plant lies among the mealy fubllance
of the feed.
Fig. 26, N O PQ, fhews the circumference of this piece or flice of
Buck-wheat, cut tranfverlely, as above mentioned, in which NOP
is the lower part of the leaf as far as it lies contiguous to the hulk,
and is that part of the leaf, which in the preceding figure is fhewn
at L or H.
From P, the leaf runs inwards into the meal, and embraces or
defends the half of that part from which the root or llem will pro-
ceed, as is denoted by the letters P V T.
The other fide of the leaf begins adjoining the infide of the hulk,
at P, lying clofe to it, half way round the feed, as far as P Q N ; fo
that in this part of the feed there is no meal next the hulk, but
C 293 )
only the leaf, though this is not the cafe throughout the whole of
the feed ; for if we cut it acrofs the middle, we fhall there find
much meal next the hulk. From N the leaf proceeds inwards, as
the letters N D S indicate ; lb that the two lower parts of the leaf
reprefented in jig. 25, at Land H, embrace or defend the whole
of the future Item, the external part of which Hem is Ihewn mjig.
2O, at the letters E and F. In this part of the flem are plainly to
be i^€^tn. a great number of veflels, and likewife in the leaves them-
felves may be feen many veliels, which here appear cut tranfverfely,
and fome of them longitudinally.
The places marked by the letters T Q V and DOS, are thofe in
which the meal is contained, and which it was impoHible to repre-
fent on the paper, therefore thofe fpaces are left vacant. This
mealy fubftance confirts of globules larger than thofe in the meal of
Wheat, Rye, or Barley; and thefe again compofed of fmaller par-
ticles or globules, fo that thefe lall are lefs than the globules in the
before mentioned feeds.
But what appeared to me worthy of note, in regard to this mealy
fubftance was, that the large globules I have mentioned, were not
of a perfect fpherical form, but every one of a peculiar fliape ; one
of fix, another of eight or more fides. In fhort, I can not any
otherwife defcribe their figure than by fuppofing a great quantity
of globules of wax, or any other loft flexible fubllance, thrown pro-
mifcuoully into a tub or box, and that, finking together by their
own weight or foftnefs, and thereby almoft all the air which had
been between them, while they were of a fpherical form, being
excluded, they loll their Ihape, and became compa6led or fqueezed
together. And thefe irregular figures they muft retain, until, being
diluted in a fulficient quantity of fome fluid, they may have room
to expand and relume their firfl: globular figure.
( 294 )
1 have examined * many other feeds, and among the reft, a fmall
feed called Manna, which is ufed to be boiled in milk, and which
I remember in my childhood to have often eaten, it being
elleemed a ycvy m holefome diet. Concerning this feed, there is a
vulgar report that it does not grow, but falls from the clouds in
Poland at a certain feafon of the year, and that it is gathered in
cloths before funrife, while the dew is on the ground. This notion
I never gave any credit to, and having procured fome of this^
jSIanna, I fa^v upon the bare infpe6lion of it, that we are much
deceived refpe<fling it, for I could difcern in every grain, the place
where the young plants had laid. But the tioie Hate of the cafe is,
that before this Manna is brought to us, it is ground in mills, in
order to ftrip off the external hufk, as is prad:ifed with Rice, by
which means, the feeds are broken in pieces, and the young plants
they contain, for the moft part, deftroyed. I difcovered, however,
many entire feeds, and in them the young future plant; from
whence the futility of the above idle tale is apparent. But it may
be true, that it is the praftice to reap and gather in this feed early
in the morning, by reafon that otherwife the heat of the fun might
caufe the pods containing the feeds to burft open and Ihed the
feed.
Being once on a journey in Gelderland, where much Tobacco
is planted, I defired to have fome of the feeds of that plant pur-
chafed for me, having never feen any.
This is a very fmall feed, being no bigger than a large grain of
fand. Upon placing one of them before the microfcope, I faw that
its outer covering or fliell, was more curioully formed than any
feed I had ever viewed with my naked eye ; and indeed it affords
fo pleafing a fpectacle, beyond any otlier feed, that, had we fuch
an objed vifible by the naked eye, we fliould not hefitate to
• The aufhor lias given fpccimcns of fevcral other fmallcr feeds, but as thej- are all re-
ducible to one or other of the dcfcrijUioiis before given, they are omitted in this tranflafion
to avoid prolixity.
( 295 )
give it a place in a cabinet of curiofities ; and, when llripped of its
outer coat or fhell, and of an inner covering or membrane, the
beauty of it is ftill more confpicuous. To give a view of this pretty
object, I caufed a drawing to be made of it from the microfcope,
and this is to be feen at Jig. 27, P Q R.
I alfo caufed a drawing to be made of the young plant taken out
of the feed, as it appeared when viewed by the microfcope : this is
fhewn at fig. 28, STVW, wherein TVW is the part which
would grow up into a plant, and W S T, the root. I had another
of thefe young plants placed before a microfcope, of which I have
alfo given a drawing at ^g. 29, X Y Z A ; and here again we may
fee how this fmall production of Nature exceeds, in beauty, many
of her larger works.
Having for fome time contemplated this feed, I took my little
brafs box, which I filled with wet fcowering fand, and placed
therein a few of the feeds : the box I carried * in my pocket in the
day time, and at night placed it in bed befide me, that it might al-
ways be warm, and thereby the vegetation of the feed be expedited,
as I had done before with other feeds ; for I was defirous of feeing
whether the young plants pictured at^g-. 28 and 29, would agree
in fliape with the plant when in vegetation.
Thefe feeds I examined every day ; the firli and fecond day I
faw no other alteration, than that they were fomewhat fwelled : the
third day, I faw that the fliell was burft open, and at the lower
part of the opening the plant had fprouted about two hair's breadth
from the fhell. On the fourth day, I faw with great furprife, that
the young plant was grown fix times as large as the original feed,
but, as I could not then conveniently get a drawing made of it, I
deferred it till the following day, when the young plant was be-
come twice as long, as it was the day before. Fig. 30, H I K L,
* Mr. LfCttwcnhock means the pocket of his brock, (;Vnglice breeches), vihich is made
large, and being next the body always warm.
( 296 )
Teprefents the two leaves which are fliewn in Jig. 28, at TV W,
and mjig. '2Q, at Y Z A.
And now I was not only convinced that, in difle6ling the feed, I
had formed a true judgment as to the different parts of it, but .
here I plainly faw tlie multitudes of vcflels of which the leaves in
great part were compofed ; and of which in the two former fub-
je6ts, pictured at //o-. 28 and 29, I had^only feen, as it were, the
Ihadow. I could moreover dillinclly fee a great number of valves
or joints in each veflel or tube, as well in the leaves, as in the llalk
and root, according to what we fee in the formation of larger
plants.
While I was preparing this object for the limner to make a
drawing of the root, as fliewn mJig. 30, at MON, I fawfo many
of the grains of fand adhering to it, that I was obliged to ufe feveral
expedients to clear them away ; and in doing this, many of the
fmall branchings from the root were broken, by reafon that they
had twined moll clofely round the grains of fand in a manner won-
derful to behold ; and if all the ramifications which I faw, had
been reprefented in the figure, the number of radicles branching
from the larger root, M O N, would have been twice as many as
here fliewn : and what is more, in many of thefe fmall radicles,
might be {ten their excjuilitely minute velfels.
The larger root, fg. 30, M ON, in a very little time became fo
dried, that in order to make a true drawing of it, and to reprefent
its velfels properly, I found it neceflary to place five or fix diffe-
rent plants before the microfcope one after another.
Now fince we fee that in fo iew days time, this fmall feed will
grow to a perfedl plant, and moreover confider, that the fame per-
fedlion in its parts which we obferve in the plant, is contained in
the feed, though hidden from oui^ eyes, we are not to wonder that
in a bird's egg, duly impregnated, a young bird fluill in a fort-
night's fpace or lefs, be completely formed, equal in fize to the egg
itfelf
( 297 )
In like manner as in feeds, fo in the buds of trees the future
produce may be diftinguiflied ; for I have, in the middle of winter,
cut off a twig from one of my bell bearing fruit trees, and on
opening fome of the buds, and viewing them by the microfcope, I
could difcover the blolToms, though w^onderfully minute. At the
fame time alfo, I cut a twig from a currant tree, and opened the
buds, wherein I faw, not only the fmall currants, which were in-
clofed in a double covering, and lay in as compadl and perfe61:
figure as fmall bunches of grapes, but I alfo faw the germ or firll
fhoot of the future young wood of the tree, which was already
formed and prepared to iflue from that part where the bunches of
currants arife in the bud. Fig. 31, BCD, are two bunches of
thefe currants feen through the microfcope, and EFG, is the germ
or flioot of the young wood.
Now, if we do not content ourfelves with merely examining
the formation of different feeds, but weigh and confider in our
minds, the wonderful and incomprehenfible perfedlion in the ope-
rations of Nature, or, more properly fpeaking, of the all- wife Cre-
ator, who in many feeds has created the future plant, with a mealy
fubftance for its fupport and nourifliment, and in others has pro-
vided for the growth of the young plant, without any fuch fupport.
When I fay, we duly weigh and confider all thefe things, we may
conclude and be aflured, that all the trees and plants now growing
on the furface of the earth, have been produced in regular fuccef-
fion from trees and plants of the fame fpecies which were created
at the Beginning of the World,
Vol. II. P P
On the Formation of Rujlies, and on the StriiBure of the Nerves,
In purfuing my obfervations on the nature of the veflels or tubes
of wood in trees, I turned my thoughts to the obfervation of Bul-
rullies. Thefe grow in great quantities in the fhallow parts of
our krger ftreams and rivers, and the feats or bottoms of our chairs
are generally made of them ; and, as they have many cavities into
which water will not eafily penetrate, they are ufed in time of war for
the making of bridges to pafs troops over fmall ftreams or canals.
Plate XIX. fg. 33, ABCD, reprefents a piece of Bulrulh,
which I cut at A, in an oblique direction, that the large cavities
with which the infide of it is for the moft part formed, and which
are vifible to the naked eye, may be fecn.
Thefe large veflels or cavities in Ruflies, are furniflied with
valves through their whole extent, without which the Rulhes would
be very brittle, and tlieir fides eafily comprefled together ; and like-
wife, were it not for thefe valves, if only one end of the Rufli M'as
laid in water, the whole would foon be filled ; but the water is by
thefe valves prevented entering the cavities otherwife than very
flowly, and the Ruflies, by reafon of the many cavities they con-
tain, can bear, when floating on the water, a'great weight in pro-
portion to their fize.
I was alfo deflrous to fliew this cavity in the Rufli when cut
Icngthwife, in order to place before the eye the valves as they are
placed in each of thofe cavities. Fig. 33, EFGHI K, reprefents
a lingle velTel, with its valves forming one of the cavities of the Rufh,
which I fliall prefently fhevv, as it appears through the microfcope,
together with the nature of its formation.
( 290 )
I alfo placed before the microfcope two fides of one of thefe
tubes or velTels in the Rufh, five of which generally form the ca-
vity of the tube, in order, if poffible, to difcover the nature of their
formation. This at firft appeared to me to be fomething fimilar to the
bafket work, or hurdles, with which our country people fence their
fields againll cattle, and which in other countries are placed on the
outfides of houfes, and afterwards daubed over with clay. Fig. 34,
L M N Q, reprefents one fide of this tube in the Rufli, drawn from
the microfcope as nearly as the limner could copy it. Q N O P, re-
prefents another fide of the tube.
What appeared to me particularly worthy of note in this object
was, that the before mentioned fides of the tubes were not com-
pofed merely of the veflels running along thofe fides, and of
which they feemed to be compofed, in like manner as I had hi*
therto conceived, that all the tubes of wood received their growth,
or confifl:ed of their own proper veflels ; but the contrary here ap-
peared to me, for I faw that each tube in the Rufli arofe from, or
was compofed of, various peculiar fmall tubes.
In fig. 34, QN reprefents a fmall tube in the fide of the cavity
in the Rufli, to which I may not improperly give the name of a
rufliy blood -veflel, and from which the fide LMNQ, in part pro-
ceeds, and from which alfo the fide Q N O P, is compofed or pro-
duced. This veflel, which I fo call a blood-veflel, and alfo all the
vefl^els of which the fides of the large veflels in the Rufli are com-
pofed, do again confifl: of many oblong parts, or rather of wonder-
fully minute veflels, from which vefl^els a great number of fmall
veflels a rife, and of thefe, the fides of the large tubes in tlie Rufli
are compofed.
Thefe minute veflels, which I call blood- veflels, and are, as I have
faid, compofed of Hill fmaller veflels, give rife to a great number of
liorizontal veflels, which take their courfe in as regular and exacl
order among the other veflels, as we may fee in the joints of the
bamboo or reed from Japan.
Pp 2
( 300 )
In order to exhibit more clearly to view, the formation of this
afcending veflel, which I call a blood-vellcl, and from whence the
lides of the large cavities in the Rufh proceed, I took one of
the fmallell of tbofe veffels, the fides of which I tore alunder as
exaftly as I could, and placed them before the microfcope, that I
might caule as accurate a drawing as pofTible to be made of them.
Fig. 35, RV, reprefents one of thefe fmall veflels, confilling of
many ftill Imallcr ones, out of which fmall veffels arife a great num-
ber of horizontal veflels, and of thefe lall veflels, as I have faid, the
tubes of Rnflies are compofed, and thefe veflels as broken off from
thofe tubes of the Rufli are piftured at S T and W.
This blood-velTcl (as I call it), R V, from which fuch a wonder-
ful produdion and fo many veflels arife is fo thin, that meafured
by the naked eye, I mufl: fay, that it is not a twenty-fifth part
the thicknefs of a hair.
But what feemed to me ftill more wonderful was, that I thought
I faw from the afcending blood- veflels reprefented in fig. 34, at Q N,
or fig. 35, at RV, and from the horizontal veflels which arofe
from thofe blood- veflels, a matter or fubflance protruded, which im-
mediately extended itfelf in length, and appeared to form a mem-
brane. But when I examined this nearer, I faw that the fide of
the Rufli's tube, Q, L INI N, was not a Ample membrane, but that
each feparate part forming that fide was manifeftly hollow, and
that the cavity was furrounded on all fides with a wonderfully thin
membrane. This cavity is fliewn mfg. 35, about and before S.
Upon difcovering this, T placed the fides fo broken off from the
tube of the Rufli, before a deeper magnifier, and diredled the en-
graver to make a drawing of two of the parts, in which he could
moft plainly diftinguifh the cavities ; and thefe are fhewn in Jig. 34,
between X and Y.
Now if we fuppofe that all thefe cavities, and each of thofe
whereof the fide of one of the tubes in a Rufh confifts, cannot be
formed but of an incredible number of fmall veflTels, in like manner
( 501 )
as vve fee the fmalleft membranes to be in the bodies of animals, we
muft again exclaim, " what inconceivable minutenels is here !"
Moreover, I cut a Rufh tranfverfely, in as thin a flice as I was able,
that I might the better conceive the formation of what' I have cal-
led the afcending blood-veflels, and bring them into A'iew.
jP/^. 36, A B C D E F G H I K L M N O P, reprefents a fmall piece
of RuHi cut tranfverfely. In E F K L S, is fliewn, as nearly as the
engraver could reprefent it, one of the before mentioned valves
or diviiions which are fhewn in Jig. 33, atEFGHIK, and, as I
have before faid, oppofe the entrance of water and give rtrengtli to
the Ruili. This formation conlills of an incredible number of vef-
fels and mebranes, each veflel being in a contrary pofition from that
adjoining to it. This valve or divilion has five diliindt fides, as at
S E, E F, F K, K L, and L S, and thus (as I have before faid) al-
mofi: all the tubes in the Rufh are formed.
Now let us fuppofe one fide of the tube in the Rufli, which in
fig. 34, is defcribed at L M N Q, to be the fame as the fide which
is reprefented cut acrofs, in Jig. 36 atLM; and moreover, that
in fig. 34, NOPQ, is another fide of the fame tube, fliewn in
fig. 36, at MN, and alfo, that what I have called a blood- veflel,
and reprefented in fig. 34, at NQ, is the fame with fig. 36, where
an oval hole is £hewn between M and O, and that this veflel is cut
acrofs.
Having made thefe obfervations, and moreover, feeing that in
various cavities of the large tubes of the Rufli, there were formed
many membranes, efpecially when the Rufli began to be fo thin, a§
is fliewn in the partition of two of the tubes in ^g-. so^ between
D E S R and D R Q C. I concluded that the fides of the large
tubes in the Rufli were formed of the fmall afcending tubes, which
I call blood-vefl"els, as follows :
From the afcending veflels placed between B P Q, the fides of the
veflels P O, Q. R, B C, B A, and P T, are in part formed ; and
alfo from the afcending veflTel placed in R, in part is formed the
fide of the tube, R Q.
( 302 )
Now when the nutritious matter is protruded from the veflel
placed in Q, towards R, in order to form the tide of the tube Q R,
it meets the nutritive fubftance protruded from R towards Q, to
make alfo the fide R Q, and when this matter or fubftance, fo pro-
truded for the formation of two diftindl velfels, and one fide of a
tube, is formed in great abundance ; it is fo comprefled on all fides,
that in the cavities of the tubes, it grows into irregular membranes,
as is here fhewn in fig. 36, between C R Q.
And this is alfo the cafe with the fuperfluous matter protruded
from the afcending blood-veflels (as I call them), in D, R, S, E, for
the formation of the fides of the tubes D R, R S, and S E, where
alfo, from the comprefled matter, the membrane placed between
D E S R is formed.
This formation, namely, each fide of the large tubes, being
formed of two diftin6l afcending veflels, is neceflary, for otherwife,
the large tubes in Ruflies would not adhere firmly. But as the
fides of the large tubes are made fo compadl, that little or no aper-
ture can be difcovered in them, fo, on the contrary, the mem-
branes, which, as I have faid before, are accidentally formed in the
cavities of the tubes, are very irregular, and have in them many
apertures, and alfo broken parts, fome of which have a cavity in
them, and their irregular formation feems to me, to proceed from
fuch extra nouriflinient not being fufficient to form entire mem-
branes.
But what feemed moft worthy of note in thefe membranes was,
that their external edge feemed a little thicker, and that, in fo thin
a fubftance as were thefe membranes, various ftreaks could be dif-
tinguilhed, which I confidered to be velfels. And indeed, I am
perfuaded, that however thin and tranfparent the membranes
might be, they were no otherwife formed than of veflels joined
together.
( 303 )
I have often, with great pleafure, obferved the texture of the
Nerves, which are compoied of very minute veflels of an incredible
thinnefs, and which, running along by the lides of each other, con-
ftitute a Nerve ; the cavity of each of thefe fmall veflels is about two
thirds its diameter; and in order to examine them I direded the
fpinal marrow of three cows and one flieep to be brought to my
houfe, that I might extra6l from thence the Nerves.
I confider it as a misfortune, that I have not been able to exhibit
the cavities in thefe Nerves to others, but no fooner do I bring them
before my sight, than in a very Ihort time, even lefs than the fpace
of a minute, they fo contract by evaporation, that the wonderful
obje^L vaniflies and cannot be reflored. And I not only faw the
fize or circumference of thefe veflels, (fome hundreds of which go
to the compoiition of a nerve no larger than a hair of a man's
beard), but fome of their cavities I could as plainly diftinguifh, as if
we were to pierce many holes in a paper w ith a fmall needle, and
hold them up again IT- the fun. And although thefe cavities, or the
orifices of thefe veflels are fo wonderfully minute, I have feen liv-
ing creatures in the waters, which could have moved and fwam
about in them with freedom. In fliort, the minutenefs of fome
things on this earth is fuch as feems to exceed all belief.
I cut fome of thefe nerves into fmall flices, or round pieces, each
little or nothing larger than the hair of a man's beard, and wetting
them, I placed them on a glafs to dry ; when dried and viewed by
the microfcope, I faw in them many fmall knobs or rifings, which
I concluded to arife from hence, that the many fmall veflels of
which a Angle nerve is compofed, became contradled upon the
evaporation of the moillure they contain, and thence arofe in protu-
berances.
It often happened to me, that w^hen I moifl:ened one of thefe
fmall flices of a nerve after it had been dried, and looked at it
through the microfcope, that I faw fome fmall particles in great
numbers, fwiiuming about in the water : thefe particles I judged.
( 30-1 )
proceeded from out of the veflels, for the knife with which I cut the
pieces off was as lliarp as a i*azor.
I am fenfible, that what I relate here will not be credited by
fome perfons, who are perfuaded that what I advance cannot be
proved by experiments or obfervations : but thefe fort of obje6tions
weigli little with me. I am indeed, by the vulgar, treated as a
conjurer, and that I publifli defcriptions of objects which do not
exift in nature, but we will leave thefe men to talk in their own
way.
I was lately exhorted by a refpeclable gentleman to go on with
my inquiries, notwithtlanding my * advanced age ; forafmuch as,
(he faid) thofe fruits which ripen in autumn, are by nature the moll
durable. I have, therefore, fet down the obfervations I have^
with no little pains, made in my decline of hfe. And, indeed, it
is no fmall trouble to purfue the inquiry into fuch minute divifions ;
and it is scarcely to be conceived how the fmallell nerves can be
divided into lb many branches.
Now, though I cannot give a drawing of a nerve cut tranfverfely,
to fliew the figure it prefented to my eye, I will give a figure of one
viewed tideways. Fig. 37, ABCDEFG, reprefents a very fmall
portion of a nerve, viewed in this pofition ; the part fliewn at AG F
is only a branch proceeding from the larger nerve.
In this piece of a nerve I coxdd not only diftinguifli the fibres of
which it was compofed, and which perform the office of veflels, but
I alio law certain cavities in each of thofe veflels, and the particles
or contents within thofe component veflels feemed alfo vifible to me.
Having feveral times cut tranfverfely, as accurately as I could, fome
of thefe minute Nerves, and moiftened them with water, I fucceed-
ed in exhibiting to the limner not only the fmall veflels compofing
the Nerve, but in every filament or veflel, of which I have faid the
Nerve is compofed, we both of us law an oblong flroke or line,
which, in facl, ^^■as no other than the cavity or orifice of the veflel
* The Author was at this time cighfy-five years of age.
( 305 )
coniprefled or collapled, as we find is the cafe with blood-veflels,
when the flefli that inclofes them becomes dry.
Fig. 38, BCDEF, reprelents this fmall Nerve, the multitudes
of velTels compofing which are cut tranfverfely, and in which the
hnes or ftrokes denote the cavities or orifices of thofe veflels. Tliis
Nerve is furrounded, in part, by five other Nerves, reprefented in
the figure by G G G G G, but in thefe I have only reprefented their
external coats or membranes, omitting the velTels they contain within
them. At four places in the fame figure, namely, at B N C, CH
ID, EKLF, and AFM, are reprefented particles of fat, witli
which particles I have fometimes fcen a fmall Nerve wholly fur-
rounded : but in lean animals I apprehend the Nerves are only fepa-
rated from each other bv their membranes ; whence it follows that
the juices deltined to form themlelves into fat, when dillributed
through the body, will inlinuate themfelves between the Nen-es ;
and, in forae part of this fame colledlion of Nerves, of but a few
hairs' breadth, I faw feven fmall Nerves, and no fat between them.
After this, I purfued my difie^lion of the fpinal marrow, until 1
could difcover the parts extended lengthways in it ; a fmall portion
of which fpinal marrow, as far as art can imitate Nature, I have
caufed to be reprefented in Jig. 39, MNOP. I alio made feveral
tranfverfe fetlions of this fpinal marrow, and at length, with great
pleafure, I faw its component parts to be placed exadlly in the man-
ner reprefented in Jtg. 38, except that they appeared rather larger
to my eye than here appears. Moreover, in many places I could fee
the light of the fun through the orifices of the veflels which I had
cut acrofs, and I pointed out the fame to the limner ; but as the ob-
jeft, in all other refpe(51:s, perfectly agreed with ^g. 38, I did not
think it necelTary to make a frefti drawing.
While I was feparating the ftrong outer coat which inclofes the
fpinal marrow, from the marrow itfelf, I faw many minute Nerves,
and, in different places, take a courfe out of the fpinal marrow ;
fome of thefe were fo minute, that what I had at firll taken for a
Vol. II. a q
( 30C )
iingle fmall Nerve I found to be five at leaft, and each of thofe five
as minute as that repi-efented at Jig. 3 7, G A F. But I wondered to
fee tliat thcfe fmall Nerves, as foon as they ifllied from the fpinal
marrow, were inferted mto the membrane that furrounded it, and
became in a manner united to it. But when they again quitted the
membrane, they feemed larger, and to be covered with a new mem-
brane or coat. But in this place I found the Nen^es, wliich I had
cut off near their origin, fo covered with fat, and furrounded with
fuch llrong membranes, that I could not feparate them to my mind.
Thefe obfervations I afterwards repeated in other objedls, for the
mod part with the like fuccefs, and in fome of them I faw the ca-
vities or orifices of the fmall veflels, compofing the Nerves, fiill more
di(lind;ly ; and, upon fhewing tlie fame to a learned friend who
called upon me, he declared that he could diftin6lly fee the fame.
Whoever wdtlies to make fimilar obfervations, mufi: be careful in
cutting acrofs fuch minute vefiels, fo to hold his knife and to make
the incifion, that it may not be in the leaft obhque. The knife alfo
muft be very fharp, and the edge of it as thin as pofiible, otherwife
the cavities of the velTels will, in the cutting, be comprelled and
clofed up.
* The Author s experiments and ohfervations refpeding the quantity
of Air contained in IFater and other Fluids.
1 HAVE leen an engine in form of a pump, defigned to extract or
pump out the air from water, but the operation itfelf I never faw.
Since that time, I turned my thoughts to the making forae fmall
inftruments for this purpofe, and from which I hoped to derive
more fuccefs, than from the pump I had feen in the hands of other
perfons.
For this purpofe, I took fome very round fmooth glafs tubes,
and of an equal breadth or bore throughout ; that extremity, how-
ever, which feemed (if any) wideil of the two, I prepared for the
introduction of a pifton or fucker.
Plate XX. fg. 1, ABCED, reprefents one of thefe glafs tubes
drawn upon a reduced fcale, for the part marked AB, was upwards
of fourteen inches long, and B C, twelve ; the cavity or bore was,
throughout, nearly the feventh part of an inch in diameter. The
cavity in the fmall glafs tube, v\ hich by the flame of a candle I had
joined to the larger tube, was one iixth part the fize of that larger
one, confequently, the contents of the larger glafs tube would be
thirty-fix times the tube C E D : this lall tube, C E D, M^as two
inches and two thirds of an inch long.
I then took a brafs wire, VL^fig. 2, G H I K, at one end of which,
with a file, I made three notches, to which end, I faftened a fmall
piece of leather, binding it on with fine filk, which filk was very
* This EfTay, and the next following, though not pertaining to microfcopical fiibjefts, arc
infcrted to.fliew the Aufhoi's diligence in his inquiijes, and the accuracy of his obfcrTations
in other branches of Natural Philofophy.
Qq2
( 308 )
firmly twilled in the middle at I : the other end of the wire I ham-
mered flat, and faftened it to a fmall wooden ball.
Having thus prepared the tube, I filled it with fair rain water,
and inferted into it the brafs wire by the end H I K, having firfi: well
tallowed the leather bound round this end, and I prefied it fo forcibly
into the tube, that no particles of water could pals by it : indeed,
fo violent was the preflure, that in this experiment, I broke four of
my glafs tubes.
This glafs tube being thus filled with water, that no air could be
feen at M, I prefled the inrtrumr nt L M, which I will call the pifton,
llowl}' into the tube, until the lower part of it, O N, at the extre-
mity N, came near to the oblique or curved part of the glafs. In
doing this, the water ilTued out of the aperture in the fmall tube D,
in a ftream like a fountain, until there was no water in the tube,
but from D E C B to N.
I then held the fmall glafs tube from E to D, to the flame of
a candle, until the heat drove out the water from E to D, which
being done, I applied the aperture D to the flame, whereby the
glafs melted, and clofed the orifice.
Having thus managed the glafs tube, that there was no air (as far
as appeared) between NBCED, unlefs from E to D, being one
fixth part of an inch, I poured a little water into the aperture A,
letting it run down and fettle upon the pillon at O, to the intent,
that if there fliould chance to be any aperture or uneven nefs in the
cavity of the glafs, water and not air might pafs by the inllrument
N O, when ufed as a fucker.
After this, I gradually drew up the pifion or fucker out of the
tube, and, while I was doing it, I faw, that not only the tube from
E to C, immediately became empty of water, and was filled with
air, but the water in the larger tube was depreflcd from C towards
R, for the Ipace of three inches ; and, during this operation, many
bubbles of air arofe out of the water, and bubbled to the fur-
face, and ftill the inore when I lliook, or with a tap ftruck
( 309 )
the glafs. At length, I faw no more bubbles of air than what arofe
from the bottom of the water. But what appeared to me in thefe
obfervations to be moll worthy of note is, that the bubbles arifmg
from the bottom, were at firll fo fmalj, as to be fcarcely vifible to
the naked eye,- and by reafon of their fmallnefs, they afcended very
llowly ; but as they rofe higher, they gradually became larger, and
afcended to the furface M'ith greater velocity.
I then again thrull; in the pillon with as much force as I thought
the glafs would bear, and in doing this, I faw that the whole fpace
of air from D E C, and three inches farther from C to B^ \\ as fo
comprefled, that the fubtile particles of air which probably had
found their way into the glafs, while I withdrew the pilton, had
not only again efcaped out of the glafs ; but that alfo the fubtile par-
ticles of air mixed with the before mentioned common air from E
to D, and alfo the thin particles of air from the bubbles which arofe
out of the water, had, by this violent prellurc, been fo forced and
driven out of the glafs, tliat there was no more fpace of air than
about the fize of two grains of land to be feen in D.
After this, I again very llowly drew out the pillon, and then
again fo many fubtile particles of air got into the glafs, that they
filled the whole of the fmaller tube and a fpace in the larger tube,
the extent of three inches from C towards B. Again 1 drew the
pillon very llowly out of the glafs, left by the too fudden irruption
of air, the glafs Ihould be broken. For it had happened to me three
feveral times, that by draw ing put the pillon too hallily, the glafs
tubes broke at C or D.
The pains I took to make thefe experiments, was for no other end
than to difcover, if poffible, what was the quantity of air extradled
from the water : this quantity, though to the eye it feemed confider-
able, yet in faft could be but little ; for each of the air bubbles
arifmg out of the water is much increafed by being mixed with the
particles of common air. Having taken the pillon out of the glafs, I
faw the water in the tube fettle itfelf at F ; fo that fuppofmg all the
( 310 V
before mentioned air to be in its natural Hate, that which came out
of the water could not occupy a larger fpace than from P to F. Now
the diameter or bore of the fmall tube DEC, being only one fixth
part that of the larger tube B C, the bore of the larger tube is
thirty-fix times the fize of the fmaller one, as before has been men-
tioned.
The water in the larger tube from B to C, flood at the height of
twelve inches, but I will only fuppofe it eleven inches, and, reck-
oning from this, I compute that all the air bubbles difperfcd
through large coUeftions of water, and extracted from it, do not
amount to one two hundred and fiftieth part of the bulk of the wa-
ter. And upon another computation made by me, I found that
the bubbles of air extracted from the water did not amount to one
two hundred and eightieth part of the water.
After this, I took boiled water and treated it in the fame manner
T have dcfcribed as to rain water, but after thrice repeating my
experiments, I could not pump out or extract any air from it ;
though, indeed, I once law a fingle bubble arife, but this, I rather
concluded to have found its way through fome inequality in the
glafs, or from Ibme water not boiled, which by ^accident was in the
tube before the boiled water was put in.
But becaufe many people may think that, in my experiments, I
could apply very little force in glafs tubes, in proportion to what
may be done by others with larger tubes, pumps, or Ijringes, I
think it right to demonlirate how much force I could apply in my
tube.
We will then take the diameter of the pifton, or bore of the tube.
<iO be the feventh part of an inch, and fuppoling that with this pif-
ton, I could apply a force equal to ten pounds AAcight, the conclu-
fion is, that in a pump or fyringe of an inch bore, a proportionable
power muft be applied, which we fliall find muil be equal to four
hundred and ninety pounds, becaufe the pill:on of this pump or
fyringe is forty-nine times larger than the other ; and if the bore
( 311 )
of the larger fyringe was two inches, the force applied muft be
equal to a weight of nineteen hundred and fixty pounds, following
the fame rule of proportion. This proves the great power I can ap-
ply with my fmall inftrument, which I have made ufe of for many
years. And thofe perfons who are any v/ife lliilled in the rules of
geometry and ftaticks, will eafily fee the truth of what I advance.
In further profecution of my inquiries on this fubjecil, I ordered
the blood of a calf to be brought to me in a clean earthen pot : after
it had llood feventeen hours, and the thin liquor which is called the
ferum of the blood, llood at the top, I put fome of that ferum into
a glafs tube, concluding that if any air was to be found in the blood,
it would be in this part called the ferum, becaufe the globules which
give the blood its red colour, are heavier than the ferum, and,
confequently, muft contain a lefs portion of air.
This ferum I treated in the fame manner as I had done the water,
and I faw, that in drawing out the pillon, a great quantity of air
bubbles arofe from the ferum ; thefe were ten times larger than
thofe I had feen iflue from the water, and adhered to the glafs like
froth. At length, having quite extrafted tlie pifton from the tube,
which was done very gently, for fear of breaking the glafs, I faw
that all the air bubbles, except a few, difappeared. This ferous
matter being thus Mdthout any preflure, I faw that the fpace occu-
pied by the air which had ifliied from it, ftood in the tube at the
heio-ht of one inch, and I computed that it was one three hun-
dred and ninety-lixth part of the faid ferum.
I repeated this experiment on the ferum, which I took as care-
fully as I could, from the blood of a calf after it had ftood only two
hours out of the animal, and I found that the bubbles proceeding
from it, were not fo many by far, as thofe in the preceding expe-
riment, but of a larger lize. The fpace of air in the glafs when
the pifton was almoft wholly withdrawn, was from C to B,
four inches and two thirds of an inch. The pifton being veiy
flowly taken out of the glafs, I faw all the air bubbles vanifli, and
( 312 )
the large fpace of air wliicli in the large tube occupied four inches
and two thirds, liad lo efcaped out of the glafs, that in the fmall
tube, from C towards E, there only remained of it the fixth part of
an inch. So that, according to my computation, the air in this
blood only occupied the one two thoufand three hundred and fe-
venty-fixth part of the bulk of the blood from which it was ex-
tracfted.
I then went to a butclicr's, at the time I knew he was about to
kill a calf, in order to extradl the air from the blood while it was
yet warm ; and for this purpofe, 1 took with me my inftruments,
and alio a glafs veird two inches diameter, and eight inches deep,
in order to catch the blood as it ilfued from the vellels of the ani-
mal ; which having done, I put fome of it, as foon as poffible, into
my glafs pump, and treated it in the fame manner as before de-
fcribed, and I immediately faw feveral air bubbles arife, which
when they came to the furface, became very large. I alfo faw th(^
blood fmk in the glafs tube from C towards B, fo that the tube was
filled with air to the height of five inches. Before I began my ex-
periment, I had accurately obferved what fpace of air was in the
fmall tube when I had clofed its orifice at D, by the means of fire..
Upon drawing out the pifton as llowly as pofliblc, I faw all the fub-
tile air, which as I before mentioned, had filled the glafs tube
five inches from C towards B, had either efcaped out of the glafs
or returned into the blood ; for I could not perceive any the leafl:
increafe of air in the fmall glafs tube from C to D. 1 then opened
the glafs tube at D, and poured out all the blood as carefully as I
could, and then put into it a frefh portion of blood, and repeated
my former method of drawing out the air ; and then I faw that the
glafs tube from C towards B, being about five inches, was filled
with air, and that fome air bubbles arofe out of the blood, which
were very large. After I had very gently drawn out the pillon, I
faw that the air in the fmall tube was increafed by the addition of
two air bubbles covered with fome blood, neither of which bubbles
( 3)3 )
exceeded the fize of a common grain of fand. But whether this
fmall quantity of air came out of the blood, or was air in the water
with which I had wafhed out the tube, before I put the fecond poT-
tion of blood into it, I cannot determine.
I then gave directions that the glafs veiTel in which the blood
had been taken, fliould be brought to my houfe, and after it had
Hood an hour, and the blood was yet warm, I poured fome of
that which was towards the furface and was now grown a little
thinner, into the glafs tube, and having flopped the orifice at D,
I again repeated my operation of pumping, and I found that the
air produced by drawing out the pillon, occupied a fpace in the
tube from C towards B, of almoft four inches, and, from the moft
exadl obfervation I could make, I found that the air in the fmall
tube was augmented only about ,i^T part of the quantity of
blood. I then left the glafs tube with the pifton extraded, and
the orifice at D Hopped, for fix hours, at the end of which time, I
faw that the lafl produced quantity of air was diminiflied more
than half.
After the blood had remained eight hours after taken from the
animal, and there was a quantity of ferum colledted on the furface,
I employed myfelf to extradl the air from it. But becaufe there
w-ere eight or ten air bubbles in the fmall tube among the blood,
I could not make fo exa6l a computation as before, but from the
infpedlion of my naked eye, I thought that there was rather a
greater quantity of air iflued from the blood.
When this blood had fl:ood in the glafs twenty-fix hours, I took
fome of the ferum off it, which I put into the glafs tube and drew
off the fubtile air, which appeared in many minute air bubbles
rifing out of the blood, and I found the tube from C towards B,
filled with air to the height of three inches and three quarters, and
drawing out the pifton as carefully as I could, I thought the air pro-
duced was yh- part of the blood.
Vol. II. R r
( 314 )
After ttie blood had remained forty-four hours in the glafs, I
repeated the experiment of pumping, but I found fuch a fmall ad-
ditional quantity of air produced, that it was Icarce worthy of be-
ing noted.
After twelve hours more had elapfed, I again drew off air from
the blood, but I perceived no alteration nor any increafe in the air
produced.
After the blood had flood about five days and as many nights in
my lludy, I took fome of the ferum from the furface, and put it into
a new tube, wherein no liquor had ever been put : the length of
this tube was feventeen inches from B to C, and eleven inches from
A to B.
This I treated in the fame manner as before, and perceived that
the air bubbles arifing from the blood, and the external air which
found its way into the glafs, occupied a fpace of five inches and
three quarters from C towards B. During my operation, I at-
tended carefully to the air bubbles as they arofe, and which grew
larger as they afcended, as I have before obferved ; and I faw fome
of them which were larger than others, rife to the furface fafter,
and fome of thofe larger ones afcended with five or fix times the
velocity of the fmaller ones. Some of thefe larger bubbles fre-
quently drove the fmaller on one fide, to make way for themfelves
in their afcent; but I never perceived any of thefe air bubbles unite
together, which I believe was only caufed by the vifcofity or tena-
city of the ferum in which they were formed.
Hereupon I figured to myfelf the reafon why a larger air bubble
fooner reached the furface of the liquor than a fmaller one. For, if
the axis of a fmall bubble is as one, and that of a large one is as
three, the proportion of a column, which the power of afcent in
the fmaller bubble will overcome, is to the larger one as one to
nine, and the bulk of the bubble whofe axis is one compared with
that whofe axis is three, will be as one to t\\'enty-feven, and con-
fequently according to this proportion, the larger bubble v»ill ex-
,^Y* ^— <K<^
•'library '
( 315 )
ceed the fmaller in the velocity of its alcent towards the furface.
And as this is the cafe with air bubbles in their afcent, the fame
will hold good in falling bodies of equal denfity, as in balls of dif-
ferent fizes, difcharged with equal force from cannon.
But to return to the fubjcdt, I drew out the pillon very flowly, and
having obferved the whole with the greateft attention I was able, I
found that the air produced in the fmall tube from C towards D,
by the operation, amounted to a feven hundred and twentieth
part of the bulk of the blood.
I know it may be faid, that my method of making thcfe experi-
ments was not fufficicntly accurate, to which I can only anlVer,
that I conducted them in the belt manner I could devife.
I made many other oblervations which I did not note down, be-
caufe I think I have lufficiently proved, that while the blood is in
the veins, or while it remains warm after taken out, there is no
other air in it, than that thin and fubtile fluid which pervades not
only our bodies, but the lubftance of all folid bodies.
Now if it be fo, that the blood contains no other air than this
fubtile fluid or medium which can pervade all bodies, and that the
quantity of common air found in blood after it has llood fome
hours, is fo fmall as not to deferve notice, we fhall reject the doc-
trine of many medical and chirurgical perlbns, who, \n hen they are
not able to aiTign the true cauie of a difeafe, fay, that the blood is in
agitation, or in a flate of fermentation, and the like. But I think
we may more afluredly than ever, lay it down as a maxim, that
every motion in the blood depends on the heart alone, and that we
ought rather to fay, the blood is too much condenfed, and cannot
eafily be driven through the fmall veflels, wherefore its circulation
is not duly performed.
But when the blood is fo much thickened that it cannot pals
through many of the fmall veirels, and thereby its courle is ob-
ftru('led, and Hill is driven from the heart with its ufual force, I
think that by this means it may be made to burlt through fome of
Rr 2
( 310 )
the I'mall veflels, and thereby produce red fpots on the Ikin ; and I
have often thought whether foniething like this might not be the
caule of thofe fmall ulcers on the ikin, which we lee in the fmallr
pox. But thefe are only my own private fpecxilations, which I fub-
mit to the judgment of thofe who make thefe matters their tludy.
In farther profecution of thefe experiments, I took rainwater well
boiled, and after it was cooled, I put it into a clean glafs, firfl wash-
ing out the glafs with the fame water, and let it Hand in my Itudy un-
covered for two days. On the third day, I placed the glafs in the
window, w'hich fronted the North-eaft, where it remained all day,
the fun lliining bright with a cold wind from the North. The fol-
lowing day I took my largeft glafs inllrument, which I rinfed out
with fomeof this water, and then filled it with more of the fame
water, then doling the end of the fmall tube, and applying my
operation of pumping, I faw air bubbles rife out of this water in
greater quantity than I had feen in rain water not boiled, but taken
out of the cillern. Having drawn out the pillon, I faw that when
the fubtle air had efcaped, a greater quantity of common air re-
mained in the fmall tube than I had before feen in the water which
was not boiled, and according to my computation, the quantity of
air produced was a two hundredth part of the bulk of the water.
I requefted a furgeon of my acquaintance, that when he Ihould
bleed any perfon, he would fend me fome of the blood ; in confe-
quence of which, I received from him a velTel with fome blood
which had been about half a quarter of an hour expofed to the air
before I received it. This blood was fo thick, that in two eflays
to fill the glafs tube with it, the air found its way into the tube,
and it was not till the third trial that I could fill the tube with
blood only ; by which means I apprehend that more air was intro-
duced into the blood, than if I could at once have put it into the
tube. Upon applying the operation of extrading the air, I faw
large air bubbles ariie out of the blood ; but upon taking out the
pifton, I found, according to the mofl: accurate computation I
( 317 )
could make, that the quantity of air extrad;ed was ttVt part of
the blood.
I was invited by another furgeon to be prefent when he fliould
open a vein in one of his pupils ; but upon this occafion the blood
iffued very flowly, and as it were, drop by drop. Some of this
blood I put into a glafs tube which had had rain water in it, and
applied the operation of drawing out the air, which I found
amounted to ^J-^ part of the blood.
Now, iince we fee that blood, when it firft iflues from the veins,
contains in it no air, we may be confirmed in the opinion of rejeft-
ing thofe fayings of medical men, who, when they are called to lick
perfons complaining of pains in this or that part, tell them, that the
wind has got into the part, or that it is a windy complaint, and the
like ; whereas they ought rather to fay, that the veffels in that part
are obll:ru6ted, that the blood or juices have not their free courfe or
circulation ; and thefe kind of obIl:rud:ions caufe pain, and fome-
times fwellings in different parts of the body.
+
Defcription of an Invention hy the Author, for ilhijlrating his Ideas
refpeSting the Effects of the Eai'tKs diurnal Motion on the Clouds
in the Atinofphere.
J\ FEW years fince, the eminent Chriftian Huygens, of Zuylichem,
paying me a vilit, our converlation chanced to tail on the diurnal
motion of the Earth ; whereupon I produced to him a glafs globe,
of my invention, which is reprefented in Plate XX. fig. 3. And,
upon my putting it in motion, he was fo much pleated with the ef-
fed, that I made him a prefent of a fmiilar globe : and having fince
frequently retleded on the lubjed:, I determined to publifli this my
invention, as illullratijig ray ideas of fome of the etFeCis produced
by the Earth's diurnal rotation on its axis, which the generality of
mankind do not attend to.
I caufed fome glafs globes to be blown, about {extn or eight
inches diameter, and with a fmall neck or aperture. Having filled
one of thefe with water, I took fome red fealing wax, reduced to a
fine po\^'der, and put the fame into the globe. I then took a fmall
leaden bullet, which would pafs through the neck of the globe, and
boring a hole in it, I fixed to it a thread, and pafi'ed the fame through
a cork fitted to flop the opening of the glafs globe, the hole in the
cork being of fuch fizc that the thread, to which the bullet was fuf-
pended, might iHck in the cork at any length required ; then putting
the bullet into the globe, I caufed it, by means of the thread, to
hang at a fmall diftance from the bottom, flopping the mouth of the
globe clofe with the coik ; then, with fome twine, 1 made a kind of
net- work round the globe, twifiing the pieces of twine together, to
the length of about a foot beyond the neck of the globe.
( 31Q )
I then placed the globe on a table, and, taking hold of the end of
the pieces of twine, I twilled them round feveral times, which,
upon lifting up the globe from the table, caufed it to fpin or whirl
round. In this contrivance I purpofed to reprefent, by the leaden
bullet, our earth; by the water, the air we breathe; and by the wax,
the clouds floating in the atmofphere.
Now, in the circumrotation or fpinning round of the glafs globe,
the leaden bullet, moving flowly, feemed as it were, fufpended in
equilibrio. But the particles of wax, which, while the globe was
at refl, lay round about the leaden bullet, now flew ofl^ from it, and
difperfed themfelves as far as the infide of the glafs globe would
permit them.
Then lowering the glafs globe, while it was yet in motion, 1 fuf-
fered it to refl on the table, upon fome paper or a cufliion, to pre-
vent the glafs being broke ; and when the globe was fo placed, I
faw the particles of wax, at firfl: in a confufed and irregular motion,
but at length they all fubfided and fettled round the leaden bullet, fo
as almoll to cover it.
Now in like manner, as by the motion of the glafs globe, the
particles of wax which at firft furrounded the leaden bullet, were
driven away and feparated from it, fo I am perfuaded that the
clouds, by the diurnal motion or revolution of our earth, are kept
fufpended in the atmofphere. And as, when the motion of the globe
ceafes, the particles of wax fubfide, and colledl themfelves round
about the leaden bullet, fuch, I am of opinion, would be the effedl
if the motion of the earth were to ceafe ; for that all the clouds,
the watery parts of the atmofphere, and other bodies that have
gravity, coidd not remain fufpended in the air, but would fall to
the earth, and there remain.
Again, if while the particles of wax lie round about and cover
the leaden bullet, tlie cork which ferves as a flopper to the globe
be taken out, and the thread which is fixed to the bullet, be fo
lengthened as to iuiicr the bullet to lie at the bottom of the glafs ;
( 320 )
then, the tliread be twilled round, and the bullet lifted up from
the glafs, it will be {ee.n by its motion on its own axis, to drive off
the particles of wax : and hence alfo w^e may gather this conclufion,
that the revolution of the earth round its axis, is wifely defigned to
drive off the vapours and moillure from its furface on all lides.
AB C D E F, reprefents the glafs globe as it lies on the cufliion,
and G H, are the pieces of twine gathered up and twifted together.
I, is the leaden bullet fattened to the thread K LD, paffing through
a hole in the cork or ftopper.
'In the bottom of the globe at A, and round about the leaden bullet,
-are the particles of wax ; but when with the hand at H, the \\hole is
lifted up from the cufliion, then by the twilling of the twine, the globe
will be fwiftly whirled about, and the particles of wax be driven to
the fides of the globe, as at B F. But when the revolution of the
globe is fuddenly Hopped, we Ihall immediately fee that the parti-
cles of wax quit the lides of the globe, and are hurried about in an
irregular manner one among another, and then colled; round about
the bullet, where at length they fubfide and fettle.
In the next place, I remove the cork Hopper and draw it on the
thread D M N P, as far as the place marked N O M, and then take
hold of the thread at P, with my finger and thumb, and gently
Awitl it, having firll laid down the twine G H, by the fide of the
globe, and then lifting up the thread N P, in like manner as I had
before done the twines G H, lb as to raife the bullet a very little
from the bottom, we Ihall fee how the bullet, in its motion, drives
off from it the particles of wax.
Certain Pojitions laid doivn hy the Author, refpcSling the Circula-
tion of the Blood in an Human Body, with his Opinioji refpeSling
the manner of exhibiting the Circulation hy the Injedion of
Quickjilver.
A HAVE heard it faid that the blood is circulated throughout our
bodies fourteen times in the Ipace of an hour; but no reafons have
ever been alligned to me from whence this conclulion was drawn.
This fubje6l has been much in my thoughts, efpecially fmce I
have {een fo much of the circulation myfelf ; and I have been con-
lidering tliat the blood which is carried to the extremities of our
feet, mull pafs through nearly three times the dillance from the
heart as that which is circulated to the top of the head. For let us
fiippofe the extremities of the feet, in any human body, to be four
feet and an half dillant from the heart, we muft at the fame time
reckon the top of the head, in the fame body, to be only one foot
and an half dillant from the heart; and, confequently, the blood
which palles through the head may perform three circuits, while
that which is carried to the feet is performing one. Hereupon I
have confidered with myfelf, how to lay down certain axioms or
pofitions whereby I might inveftigate this matter, upon fufficient
grounds, without paying any regard to bare affertions; and only
admitting this lingle faft, that the blood adlually does circulate to
and from the extremities of the hands and feet, as well as the reft
of die human body.
Upon relle6ling how fwift a motion the blood appears to have in
the arteries, when viewed by the microfcope, though when exa-
VoL. H. S s
( 322 )
mined without the help of glalTes the circulation feems to be flow;
I have, in my mind, divided a minute of an hour into fevcnty-
two parts (inftead of fixly feconds, as is the common way of di-
viding time), and I reckoned each of thefe feventy-two parts or
portions of a minute, to be of fuch a length, that in it a perfon can
dillindly pronounce a word of four fyllables.
I then took an eel, about a foot long, and placed it before the
microfcope, and, from the mod corred obfervation which I could
make, I judged that, in the feventy-fecond part of a minute, the
blood in one of the arteries, which was of a fize to admit three
or four globules of blood at a time to pafs through it, had pro-
ceeded the fpace of a fifteenth part of an inch; therefore the blood,
in one minute's time, palled over a fpace of four inches and four-
fifths of an inch; and this number being multiplied by fixty mi-
nutes, it follows that the blood in this eel could be carried or driven
forward 288 inches in the fpace of an hour.
Now, let us fuppofe that the heart (which in eels is placed near
the head) was in this eel diflant from the end of the tail, where the
farthefl extent of the circulation is performed, 1 1 inches, it follows
that the blood, in its circulation, mufl be carried twice this dif-
tance, being 22 inches, before it returned back to the heart ; and
dividing the before mentioned number, 288 by 22, wefliall find that
in this eel the blood circulated to the extremity of the tail and back
to the heart, fomething more than thirteen times in the fpace of an
hour.
In the next place, we will fuppofe that the ends of the blood-vef-
fels in the head, and in the fins next to the head, were in this eel
one inch and an half diflant from the heart, and, confequently, that
in thefe veflels the blood only performed a circuit of three inches;
it will follow, by the fame mode of computation as before, that in
thefe parts the blood might perform its circulation ninety-fix times
in the fpace of an hour.
( 323 )
Laftly, if we advert to the blood-veflels in this eel, in and near
the heart, where probably the blood is not protruded the fourth part
of an inch before it is carried back to the heart, we fhall find that
in thofe veflels in and near the heart, the circulation may be per-
formed an inconceivable number of times in an hour,
I have many times endeavoured to fee the current and circulation
of the blood in quadrupeds, which always live on land ; but I never
could difcover it: among birds, I found a fpecies in which I could
moll plainly fee the motion of the blood, but I could not diflin-
guilli the complete circulation, by reafon of the great number of
blood veflels, which caufed the part I viewed to appear red.*
Now, if we take for granted that in our own bodies the blood is
carried through the arteries with the fame degree of fwiftnefs as in
eels, and that the extremities of the feet or toes are diftant from the
heart in any human body four feet and an half, or fifty-four inches,
making the blood perform a circuit of ] 08 inches, it will follow
that the blood is carried to the extremities of the feet, and brought
back to the heart, in the fpace of an hour, only two times or circuits,
and two-thirds of another circuit.
In the next place, fuppofing the blood-veflels at the extremities
of our fingers to be two feet and three-quarters, or 33 inches,
diftant from the heart, making a circulation of 66 inches, we fliall
find, by the fame mode of computation as before, that here the cir-
culation can be performed 4 Vt times in an hour. By the fame rule^
in thofe blood-veflels in the breafl:, and other parts in the body, only
twelve inches diftant from the heart, the circulation may be per-
formed twelve times in an hour ; and in thofe veflels in the far-
theft part of the head, which may be fuppofed 18 inches diftant
from the heart, the circulation may be performed eight times in an
hour.
* A ceck's comb and gills, Vol. I. p. CO.
S S 2
( 324 )
But, if we make a calculation on thole veflels in the body which
are \\ ithin twelve inches diltancc from the heart, and confider more-
over how many veflels there are very near to the heart, and even in
the heart itfelf, here we Ihall find that the circulation may be per-
formed in a very fhort fpace of time.
Upon the whole, it may probably be true, that in an hour's time
there pafles througlj the heart fourteen times as much blood as the
whole body contains: but it cannot be faid that all the blood in
our bodies performs its circulation fourteen times in an hour, foraf-
much as we have feen, from what is before laid down, that in many
parts of the body this cannot be the cafe; and in particular in the
feet, where it appears that the blood can, in an hour's time, perform
no more than two complete circulations, and two-thirds of ano-
ther.
I am aware, that many may objecfl to thefe my pofitions, refpedl-
ing the circulation of the blood, and fay that I have feen it, in frogs
and in fi flies, only at the extremities of their bodies, where the mo-
tion of the blood is exceedingly flow; but that, if it could be feen
in the veflels near the heart, there its motion would be found to be
much fwifter : and, in proof of thefe opinions, they reafon 'by
analogy to what we obfene in the motion of a Iblid body in the air,
fuch as an arrow or a bullet, which moves with great fwiftncfs when
firfl difcharged, but whofe velocity continually diminiflies: fo, fay
they, the blood mufl move with much greater fwiftnefs in the veflels
next the heart, than in thofe vefl^els of the fame flze which are near
the extremities.
To this I anfwer, that the motion of the blood in our bodies, or in
the blood-veflels in fiflies, has not any analogy to the motion of a
folid body in the open air; and in proof hereof I have cauled a
figure to be drawn, which may be feen in Plate \X.fig. 4. A B C
D E F, which we will fuppofe to reprefent a leaden tube, from
whence various fmaller tubes branch forth, as at B G, C H, D I,
E K, and F L, and that this tube and all its branches are filled with
( 325 )
fome liquid, fuch as water or blood, or any other fluid ; and in the
larger tube let there be a pillon or forcer, as a A B. Now, I fay,
that if the liquid in this tube be comprefl'ed, the fmall branch, B,
which is next the forcer, will not endure a greater preflure than the
branch, F, which is the moll ditlant from it.
And though the fmalletl tube, F, be a million times lefs than the
largell one, the preflure of the liquor will be the fame in both.
To illurtrate this by another example. Let the diameter of this
largell round tube be reprefented by a fquare veflel, fg. 5 , A B C
DE F, the meafure of one of whofe fides lliall be as 5, the fquare
of which is 25 ; then let the fmall round tube be reprefented by
a fquare one, as ?itfig. 0, which call 1, being formed of one of the
divilions oi fig. 5, then this fmall fquare tube will be to the large
fquare veflel in the proportion of 1 to 25.
Now, let us fuppofe the large fquare veflel to be filled with fome
liquor, which is prefled with a force equal to one hundred pounds,
the bottom of the veflel, AFE, befides the weight of the liquor,
will futfer a preflure of one hundred pounds; but to prefs the bafe
of the veflel. Jig. Q, H, with the like force, will only require a
wreight of four pounds ; and if lb, the preflure on the bafe H will
be exactly proportioned to the prefl^ure on the bafe AFE, becaufe
this is twenty-five times larger than H. And we may even fay,
that if only the weight of a grain of fand was imprefled on the
part a AB, infg. 4, there is no reafon why this preflure fliould not
be felt in all the fmaller tubes at the fame moment as in the larger
one ; for, as the whole of the water or other fluid is to be confi-
dered as a folid body, there is nothing to prevent fuch impreflioh
being fo felt.
Thefe reafonings of mine will be very eafily underftood by any
one who is acquainted with the principles of hydrollatics, as laid
down by Stevinus.
But if we fuppofe the part A, in. fig. 4, to be fome feet higher
than F or L, it may be faid that the water in the fmall tubes, F and.
( 326 )
L, will be more comprcfled than in the tube B, folely by reafon of
the gravitation of the liquor, if B is placed higher than F and L ;
but if the liquor in thefe fmall tubes has a paflage into other fmall
tubes, in which the liquor can riie to the height at Q, then the
preflure on the liquor will be the fame in all the other tubes ; for the
prefllire is the fame in every part of the tube as at its bafe, regard
being had to the diameter or breadth of thofe tubes.
In a word, the current of the liquor will be of the fame fwift-
nefs in every one of thefe branches.
Now, if we conlider the large tube, j^^. 4, A B C D E F, to be an
artery, and out of it various fmall arteries and their branches
arifmg, as B G, CH, D I, EK, and FL, and that MNOPQR
is a vein into which the arterial blood is difcharged, we mull necef-
farily fay that L M, K N, 10, HP, and G Q, are veins, becaufe
G H I K L are the places where the blood begins to take its courfe
backwards.
But the circulation of the blood will be very much retarded in
the extreme parts of our bodies, when the limbs are cold ; whence
it comes to pafs that the blood-vellels in thofe parts are fo diftended
that our hands and feet are fwelled, and therefore there cannot be
fuppofed to be fo rapid a motion of the blood in the extremities, as
in thofe veflels which lie in the more internal parts of the body,
unlefs all the parts of the body are equally warm.
A certain Dodlor of Phyfic, to whom, among other perfons, I had
fliewn the circulation of the blood, told me that this circulation
had alfo been exhibited to him by a chirurgical gentleman ; and on
my defiring to know how it was Ihewn to him, he faid by injeding
quickfilver into an artery, which circulated back again through a
vein ; but when I atked him how they were aflured that one of the
veflels in which the experiment was made was an arter}', and the
other a vein, he anfwered that they were not certain as to that
point. I alfo alked him what was the lize of the vein in which the
quickfilver, fo injeded, was circulated ; to which he anfwered, that
( 327 )
it was above a thoufand times larger than thofe velTels in which he
had feen the circulation of the blood at my houfe.
Hereupon I told him, that in this cafe a perfon might very eafily
be deceived ; and that the veiTel or veflels to which the names of ar-
teries or veins were given, might, in my opinion, be either one or
the other; for that I had myfelf, at times, feen various veflels in
which I concluded the blood had performed its circulation, and
which were fo large that they might be difcerned by the naked
eye, but that, in thofe inftances, I had always been miftaken ; for,
upon a more clofe examination, I had found that thofe feveral vef-
fels had arifen out of a branch of one and the fame blood-veflel.
To illuftrate this by an example :
Let A B C D E F G, in fig. 7, reprefent a vein, Vv'hofe two
branches are both cut off at B and E, fo that we do not know that
each of thefe is a branch ifluing from the vein A. Thefe two vef-
fels, BCD, and E F G, we find again united by the veffel E F, as
the blood-velTels are often joined together ; and out of thefe vef-
fels, by fqueezing, pinching, or rubbing, we may extrad any blood
that might be left in them. Now it may very eafily happen, that
in extracting the blood, or by the ftrong injedlion of quickfilver or
wax, the valves (if any fuch there are in the veflels) may be broken,
and then the quickfilver or wax, fo inje6led, may be forced through
that part of the veflel marked B C F, and return from F to E ;
whereupon BCD will feem to be an artery, and E F G a vein, and
it will be thought that the circulation is performed through C F.
When velTels of this kind have formerly been viewed by me, I
have found myfelf to be miftaken in fuch concluflon ; for, upon
farther examination, I have found (as before mentioned) that both
the branches BCD, and E F G, arofe out of the fame vein, A.
Again, fhould we meet with an artery, as reprefented in fig. 8,
I KL, into which we injedl quickfilver until the whole veflel I K L
is filled, lb that we may be certain that in this veflel the blood is
brought back from K to L towards the heart; neverthelefs, we
( 328 )
cannot fay that I R is an artery and K L a vein, becaufe in tliofe
veflels, which are villblc by the naked eye, the blood is not carried
from and alfo back to the heart in circvdation ; for \\ here I have
obfervcd thefe arteries to liave a bend, I have often perceived that
they were fpread into branches, as is here flicwn at L, and thcfe
again into fmaller branches; fo that at firft fight we might fay that
the circulation is performed in JNI N O, and that M P Q, N P Q,
and O P Q, are veins.
I was formerly of opinion, that the blood which, in the arteries,
is carried to the extremities of the body, did, in its parage, gra-
dually lofe part of its thinner juices, by the continual puliation of
the blood forcing thofe juices through the coats of the arteries.
But, after frequently contemplating the circulation, I am aflurcd
that the coats of the arteries are lb formed, as not to permit the
leall particle of the blood to pals through them, until thofe arteries
become divided into fuch very fmall branches, as give paflage to no
more than one, two, or three globules of blood at a time ; at which
places the circulation or return of the blood to the heart takes place ;
and here, through the extreme thinnefs of the coats of the velfels,
the liner juices of the blood may find a palliige on all fides for the
nourilliment of the parts adjoining. For were it otherwife, not
only the external parts would want a due proportion of nourilli-
ment, but the circulation of the blood itfelf could not be performed
to anfwer its intent ; for the external parts of the body require the
greatell fupply of thin juices, by reafon of the great expence of
moillure they are expofed to from perfpiration and otherwife. But
if the blood was carried both to and from the heart in circulation
in the veflels, which are fo large that we can injeft quicklilver or
warm wax into them, and are of fuch a fize as to admit two or
three thoufand globules of blood, or more, to pafs through them at
a time, and the coats of thofe arteries being, as I conceive, fo folid
and- impervious that they will not fuffer the very fine juices to pafs
through them, the confcquence would be, that in thofe large vef-
( 329 )
fels, the blood would be brought back to the heart without bene-
fiting the bodj ; whereas we may be allured that the blood is cir-
culated through the vellels for no other purpofe than to dillribute
nourilliment to every part.
If we cut open an artery or vein of any animal, out of which
the blood is emptied, we fliall find the infide of it as clean and
\\hite as if no blood had ever been in it ; which I think is fufficient
proof, that thefe veflels are formed in fuch a manner as to retain
the thinner juices of the blood in every part, except where they
are divided into the moft minute ramifications. Nor will this feem
ftrange to us, if we confider thole fowls which fwim on the water,
and there leek their food ; for we know, that how long foever they
remain in the water, or how often foever the water covers their
feathers, yet thofe feathers do not at all imbibe the water.
I have llripped off the very thin membrane, or internal coat of an
artery, and placed it before the micro fcope; when I faw, with ad-
miration, that it was compofed of an inconceivable number of ex-
ceffively thin parts, interwoven one among another, and linked to-
gether in the manner of a net : and when I examined the other
coat of the artery, which covered the laft mentioned, I faw that the
parts of which it was compofed, were carried round about the ar-
tery ; fo that the ftrength of fuch coat confifted in its being capa-
ble of great extenfion and contrattion in breadth, more than in
length.
Seeing this, I concluded that every time the blood is driven from
the heart, all the arteries expand themfelves, which mull occafion
a pulfation throughout all thofe arteries ; and as by this means they
are every time ftretched beyond their ufual width, they are fo
formed and conllituted as immediately afterwards to contrail
themfelves, which contraction promotes the propullion of the
blood in thofe arteries, until it i-eaches thofe vellels we call veins.
But the contrary, in my opinion, takes place in the blood-vellH
which we call a vein ; for a vein, when emptying a part of its con-
YoL. TI. T t
( 330 )
tents into the heart, muft neceflarily at that time be contrafted more
than when in its natural ftate, becaufe there cannot be a vacuum in
the vein, and there is no fubftance at hand to occupy the place of
the blood poured into the heart ; for the blood cannot flow from the
extremities, or even the parts adjoining, in fo Ihort a time as would
be required, whereupon mull follow, as before obferved, a more
than ordinary contraction of the veins.
But thofe parts, of which the coats of the veins are compofed,
which almoft all take their courfe round about the vein, thefe,
upon the effufion of the blood into the heart, being put in motion,
by their undergoing fuch contradlion as before mentioned, will, by
their elaftic tendency to recover their natural ftate, draw the blood
from the moll diftant parts towards the heart; fo that this may be
confidered as a third caufe of the conftant circulation and current
of the blood.
Ow the nature of Lime, and other hinds of Cement.
In order to difcover the reafon why Lime and Plaifter, being
moiftened with water, do, upon drying, acquire a degree of hard-
nefs like Hones, 1 took a piece of Limellone, which, by being burnt,
is rendered very foft, and divided it into very fmall particles ; thefe
I moirtened with pure rain water, and placed the mixture before the
microfcope : I did not at firft obferve it to undergo any alteration ;
but, continuing my eye fteadily and inceflantly fixed, both on the
fmaller and larger particles, I perceived, after ten or twelve minutes
had elapfed, a faint appearance of exceffively thin and minute faline
particles ; at the end of fifteen minutes I faw them very dillinclly ;
and in half an hour I faw, not only in every particle of the broken
Limeflone, but alfo in the water itlelf, fuch a multitude of faline par-
ticles as is almoft incredible. Thefe minute falts were not formed
in flraight lines, lying fide by fide, but for the mofl: part they crofled
each other in all directions. For example: I faw a particle of Lime-
flone lying diflinft by itfelf; this particle was more than a thoufand
times lefs than a grain of fand, and in it more than fourteen falts or
faline particles were formed; they were not all of the fame fize,
but fome larger than others, and alfo of different thicknefles ; but
the two longeft fides were all flraight, and parallel to each other ;
the two ends, or fliortefl fides, were obliquely fliaped, yet
parallel. This particle, with the falts which fliot or pro-
ceeded from it, as feen through the microfcope, are repre-
fented by the figure in the margin.
By the fight of this great quantity of falts lying together in this
irregular manner, and efpecially where the particles of Lime lay
T t 2
( 332 )
clofely heaped together, I was fully fatisfied as to the caiife of the
hardnefs or cohefion which Lime acqiiires after being moillcned ; for
the falts flioot from it, one among another, in all directions, and
being foft when firfl; formed, they muil, as they harden, become
clofely coagulated, and fixed to each other, fo that not a tingle fait
is formed in the fubllance, but it is united or connefted with others :
and I am fully convinced, that the hardnefs or ftrong cohetion we
find in Lime when made into Mortar, arifes only from the Inline par-
ticles or minute falts produced in it, which are of fuch a nature,
that when once formed, and thoroughly hardened and compadled
together, they can never afterwards be dillblved, unlefs by the
powerful efFe6l of fire.
In relle6ling on the nature of Lime, as thus defcribed, I began to
think that if the Mortar of old buildings were burnt over again,
the faline particles formed in it would be fo diflblved that it might
be again moiliened with w^ater, and become ferviceable as before.
In order to make trial of this, I took fome pieces of dry Mortar
from the roof of my houfe, and heated them red hot ; wdien cold
I found they were become fo foft, that they might be crumbled to
powder between the fingers ; and, upon wetting this powder with
water, I found it to poflefs all the properties of new-made Lime.
Now% fmce we find that the faline particles in Lime or Mortar are
the only reafon that Mortar or Cement, when dry, becomes hard or
ftony, and that if the fame be again burnt it becomes foft, all thofe
faline particles being dilTolved, infomuch that we can crumble it be-
tween our fingers, we may be well afi^ured that Lime is unfit to
make Mortar or Cement for w^alls of buildings wherein great fires
axe to be made, and that the proper fubtlance for fuch kind of work
is good Clay, which becomes the harder the more it is expofed to
the fire.
I alfo concluded, that this Ihooting or formation of falts in com-
mon Lime, mull alfo take place in that kind of Cement which is
called Tras, or Terras, which is of that nature that it acquires a ftony
( 333 )
hardiiefs, even under water, and is therefore ufed in the conftrudion
of water-works, and in other buildings where more than ordinary
ftrength and foUdity are required.
This fubftance called Tras, is brought to us down the Rhine, and
is ground to powder in windmills conll:rucled for that purpofe, and
being mixed with common Lime, it is beaten or worked together a
very long time," even for feveral days ; for it is faid, that the longer
it is beaten the better it is : and, in order to make work firm and
llrong, it is cullomary to ufe three parts of this Cement or Tras and
four of Lime.
A piece of this mixture of Lime and Cement, taken from an an-
cient building, I heated red hot, and when it was grown cold I found
it fo foft, that it was eafily reduced to powder. This powder I
mixed up with water, and perceived a great quantity of bubbles
arife from it, the fame as we obferve in frefli Lime ; after this had
flood for an hour, it was grown ftifF. I then beat it, or mixed it up
again, and in a Ihort time it becanie exceeding hard.
This repeated beating, or working up of the Tras or Cement, is
of very great ufe, becaufe, by this means, the air bubbles formed in
it are expelled; for want of which being done the Cement cannot
acquire its proper firmnefs. This appeared in the fmall portion of
Cement which I have jull faid that I mixed or worked up only twice ;
for, after it was become dry, I broke it in pieces, and found in the
middle of it many round cavities, which I concluded to have been
caufed only by the bubbles of air in it. But, when the Cement is
beaten or worked together for feveral days, not only the air bubbles
are expelled, but, after, a certain time, no new ones are formed in it;
and I am certain that if our common Lime was to be beaten or
worked up for as long a time as the Tras or Cement, the bubbles
of air which are formed in it would be all beat out, and the labour
more than twice repaid by the goodnefs of the Mortar, efpecially
in cafes where folid and durable work is required.
( 33 1 )
Addition, by the Translator.
On the fame SuhjeB ; from Styieaton's Narrative of the Conjlru&ion
of the Edyjlone Light-Houfe.
IN this work, Mr. Smeaton has given an account of his examination
of all the fpecies of Lime or Cement that came to his knowledge ; and
he ranks among the firfl;, or mod powerful, the Terras defcribed by Leeu-
wenhoek ; and alfo Puzzolana, which is a Cement of the fame kind, brought
from Italy, as the former is from Germany. Both of thefe are fuppofed to
be volcanic productions ; and if fo, they are fubflances prepared by Nature,
in the fame manner as Lime is by art, namely, the operation of fire. Mr.
Smeaton recommends, for water buildings, the mixture of Terras or Puzzo-
lana, with Aberthaw Lime, and he approves of repeated beating of the
Mortar fo made, as it thereby acquires the greater ftrength.
Mr. Smeaton's fentiments on the preparation of thefe Cements, entirely
agree with thofe of Mr. Leeuwenhoek, though our Englifh Engineer feems
to have been ignorant of the caufe of the cohefion of Mortar, and of the
reafon why it is improved by beating ; which have been fo accurately invef-
tigated and minutely defcribed by the Dutch Naturalift.
The Author s Difcoveries and Ohfervations refpeB'ing Wood con"
fumed hy Maggots.
V^ASTING my eye in the winter feafon on fome pieces of oak,
(called in this country, Tel-hout), which I had kept in my houfe
about fix years, for fire-wood, I faw that it was almoft wholly co-
vered with a kind of white powder of the fame colour with the
wood. Conceiving that this dull: was caufed by fome maggots con-
cealed within the wood, I took out of the heap a piece of wood very
much covered with this powder ; it had been cleft lengthwife, was
about an inch thick, and eighteen inches long, and of five years
growth ; but I could not fee on the furface of it any of thofe mag-
got holes which we fee in many woods, although I had wiped off
all the powder it was covered with. I then cut it in half, and hav-
ing fplit the pieces, I took out of one half of it feventeen white liv-
ing maggots, all of the fame fize ; their bodies were Ihort, and
when taken out of the wood, they rolled themfelves up in a kind of
circle : their fore part was twice as thick as their hind part : more-
over, when taken out of the wood, they were not able to creep
along ; their feet were very fliort and covered with many hairs, and
on each foot a ftraight claw. Thefe maggots had clofely compref-
fed the particles of wood which they had gnawed off, and alfo the
excrements left behind them in the winding channels they had made
in the wood, which I wondered they could do, becaufe their bo-
dies were very foft, except the organs they had in the fore part of
their heads, and thefe were not white, but of a yellovvilh colour.
Although I had no doubt that thefe maggots in the fummer time
would be changed into flying animals, I neverthelefs put fourteen,
of them into a little box with a cover, which fcrewed on, and
thefe I carried about me, to difcover how long they would live.
( 330 )
111 the profecution of my oblervations on this fubje<5t, I was
aftoniilied to fee that the wood, on the furface of which there was
no appearance of biting or perforauon, was yet fo gnawed through,
that it would eafily break. Now when people in general fee fuch
pieces of wood, which on the outfide appear quite uninjured, and
yet fo brittle, and contain fo much dull or powder, they think that
the wood has a natural tendency to decay, or that it is confumed
by maggots bred in the wood by fpontaneous generation, becaufe,
as I faid before, they fee no holes in the furface.
But if we confider how fmall thofe eggs mull of neceffity be, from
which fo minute an animal is produced, as proceeds from thefe IMag-
gots by tranlmutation, and that a Maggot newly hatched from fuch
an egg may creep into the chinks or cracks, or even the large vef-
fels of the wood, and pierce holes in it fo fmall, as at firtl to efcape
the notice of our eyes, we may in fome meafure folve the diffi-
culty.
I was well fatisfied in my mind, that the flying animals to be pro-
duced from thefe Maggots would be of the fpecies whole wings are
covered with fliells or cafes, and to fatisfy myfelf in this refped:,! took
about a third part of the fame piece of wood (from which part I had
not taken any maggots nor could I difcern any holes perforated by
them in the furface), and inclofed it in a glafs tube, each end of
which I flopped with a cork ; this tube I put in my clofet, in a
place where it would be often expofed to my view, and that thus I
might difcover what would become of the INIaggots, if any there
were, in it. This piece of wood I often looked at, but could not
perceive any alteration, except that there appeared fome particles
fcraped or bitten off the wood which lay in the glafs, and alio a
INIaggot which had crept out of it and was dead.
On the 2 1 11 of May, feeing no farther alteration in the wood, I took
three other fmall thin pieces of the fame fire-wood, which I broke
and took out of them about thirty Maggots, which were now
changed into aurelias or cryfales, and as yet of a very white colour :
( 337 )
thefe cryfales were very prettily Ihaped, for in tliciii I could plainly
fee their eyes, curioufly formed of various optical organs, having the
refemblance of bunches of grapes ; and I alfo thought that each eye
confifted of more than two hundred fuch optical organs, befides
which there were plainly to be feen the like joints, rings, or creafes
as in the maggots, allb the horns on the head, the feet, and the
Ihells or cafes for coverings to the wings ; and, in a word, there
appeared fo many and fo great perfections in this infigniticant ani-
mal, that I could not view them without allonillmient.
In about three weeks from this time, my occafions having called
me out of town for a few days, I obferved at my return that all the
animals which I had put into a box were changed into flying crea-
tures, excepting two or three who were dead and their bodies dried
up, and thefe [ fuppofcd I had injured in taking them out of the
wood. I alfo faw eight flying animals, which had ifliied from the
fmall piece of wood I had put into a glals tube, fitting upon the
wood, and feveral round holes pierced in the w^ood, through which
I concluded they had efcaped
Thefe flying animals were, in my judgment, fix or eight times
larger than that which is produced from the maggot which feeds
on the oily fubllance of Wace, of which I have treated at large in
another place. The fliells or calcs alfo, -which cover the wings,
are nearly of the fame fliape in both fpecies.
From hence we fee that fuch young flioots of oak, as I have be-
fore mentioned, are more liable to be con fumed by maggots than the
larger pieces growing in this country, and much more flill than
thofe which grow in warmer regions : and for this there can be no
other reafon afligned, than that thofe fmaller pieces of wood, which
afc the flioots which fpring from the roots of old timber trees, and
grow up into faggot wood, are in this country very flow in growth,
and confequently very porous ; whereas the pieces or flioots of oak
which are of quick growth are firm and folid, and thefe maggots
Vol. II. U «
( 333 )
can make but little impreflion on them, and the reafon * of this
ftrength and iirmnels in oak timber has been explained by me in
another place.
Moreover, thofe pieces of wood which are left with the bark on,
are more obnoxious to be injured by maggots than thofe which are
firipped of it, becaufe, as I conceive, the maggots, while young,
are more able to gnaw into the bark than into the wood itfelf ; but
when they have fed upon the bark for fome time, they by degrees
grow flronger, and are better able to gnaw the wood : of this we
have a proof in balkets, which are much lefs liable to be injured by
thefe maggots when made of white wauds than of thofe which
have the bark on.
* Vol. I. p. 5 and 6.
Defcripfion of a minute Fijh, found adlierbig to the fliclh of Sea
Fl/h : the Author s Examination of the Eyes of Flies and other
fmall Animals, and his Ohfervations and Conclufions thereon.
1 HAVE often taken notice of certain knobs or rifings which
fometimes are feen in great numbers on tlie lliclls of nnifclos,
though on other lliells none are to be found. I have aUo {cen tlieni
on oyfters, and I have counted as many as fifty on one fliell : thefe
knobs or fweUings, are called by our common people, puftules, or
pimples. They are confidered by many to be only cafual excref-
cences on thofe fliells ; but, if we examine them carefully, we fliall
find, that they are in reality fmali fiflics fixed to the fliells of muf-
clcs or oyfters, where they gradually increafe in fize ; fo that I once
faw on an old mufcle one of them, whofe diameter at the bafe was
three quarters of an inch, and there were many other fmaller fiflics
of the fame fpecies, but of difi^erent fizes round about it.
Thefe fmall fifties, which I call Pulhile-filh, or Pimple-fifli, are
fixed by their fliells on different parts of the oyfters or mufcles. But
whereas, oyfiers and niulcles, when feeking their food, open
their fliells a little, thefe fmall fifli are inclofed by a folid fliell on
all fides, except an opening at the top or point of each fliell, in
which opening are placed two very minute oblong fliells, not fixed
to the other fliells, but to the fifli itfelf, and by the help of which
it can clofe the opening in the other folid fliell. Thefe two minute
pieces of fliell have each of them a flraight fide, exa6lly fitting each
other ; the other fides are rounding and floped to a point.
Upon putting fome mufcles, to which feveral of thefe fmall fifli
w^cre fixed, into fait water, I faw the fiflics protrude thefe fmall
flielly parts beyond the aperture, and open the extremities of them
about as wide as the back of a common knife, and upon my touch-
ing thofe parts lightly with a fmall needle, the fifli immcdiatelv
doled them, and alio drew thofe flielly parts A'sithin the folid fliell
Uu2
( 340 )
which thus became fliut. Thefe fmall fiflies lived only two days
while in my poflefTion, but how long the miifcles to which they
wei-e fixed, had been out of the water \s'hen I got them, I do not
know.
I have often taken thefe minute fifties as gently as poffible out of
their fliells, and fpreading their parts afunder, placed them before
the microfcope, and I mufi fay, that I never with my naked eye,
beheld any fifh, in the formation of which there appeared fuch
wonderful art, as in thefe minute fiflies ; therefore I determined to
give a drawing of the greatefi part of one of them.
Plate XX. fg. 9, A B C D, reprefcnts part of a mufcle fliell, in
which, at E, is flievvn the flicU of this fmall fifli, as faflened to the
mufcle ftiell, and which, as I have faid before, is called a Puftule,
or Pimple.
The wonderful and curious formation of this little fifli, the lim-
ner could not reprelent exad;ly after Nature, becaufe the beauty and
regularity of its fliape were loft when the moillure evaporated from
it ; and befides, the feveral parts of its body were fo exadlly and de-
licately joined together, that when I endeavoured to fpread them
afunder, fome one part or other was always broken.
This fifli is provided with a receptacle containing a great number
of eggs, but which, at the leaft evaporation of the nioifture, are fo
contra6led, that nothing of them can be diftinguiflied.
Fig. 10, A B C D E, reprefents the body of this fifli as (cen by
the microfcope. E F, is one of twelve organs or limbs with which
it is provided, befides the other organs marked K L M, N O, and
P Q R. All thefe organs lie bent in a kind of curved pofition, and
are fo twilled one within another, that they cannot be diftinguiflied
uniefs they are gently fpread afunder.
I have faid, that the eggs were fo foft, that on the leaft evapo-
ration they loft their fliape and vaniflied from the fight, therefore I
determined to boil fome of thefe Pimple-fifli a little, and by fo doing,
the eggs acquired fuch a degree of hardnefs, as to keep their figure,
and enabled the limner to fee them diftindly and reprefent them in
his drawing, as may be feen in fig. 10, at G H I. But I direded,
( 341 )
that only a few of the eggs fhould be reprefented, for if all thofe
eggs whicli lay about that part of the body marked ABC, had been
inferted in the figure, the number would have been ten times as
many as here fliewn: moreover, it is to be obferved, that all thefe eggs
were held together by a kind of membrane, and in fuch exact and
regular order, that it was a pleafure to behold them. On farther
examination, I perceived in each egg a round corpufcle like a yolk,
and each egg was compofed of a great number of larger and fmaller
globules, as I have always obferved all eggs, or at leaft the yolks
of them, to be formed.
I have given a drawing of this minute animal, for no other rea-
fon, than to convince thofe perfons of their error, who abfurdly
maintain, that a living creature can be generated from corruption,
by fbewing the wonderful formation of fo minute and contemptible
an animal, and which not one man in a thoufand knows any thing
of, not to mention that many veffels, nerves, and organs, worthy
of admiration, may be feen in this fmall creature, when firft taken
out of the fliell, and while the parts of its body remain moiil.
I have often made repeated difledlions of the eyes of various
kinds of Hying infects, merely on account of the pleafure the con-
templating them afforded me.
In particular, in the fummer feafon, I examined the eyes of that
large flying infe<5t called the * Dragon Fly. Thefe being placed on
a Iheet of clean paper, with a fmall hair pencil and fair rain water,
I cleared away the many veflels which fill the infide of the tunica
cornea, or horny coat of the eye, leaving only the tunica cornea
remaining. This I contrived to place in fuch a manner, that it
mioht not, as it dried, contrati in wrinkles, and placed it before
the microfcope, and I often contemplated it with great admiration,
for I not only faw the many parts or optical organs of which it was
compofed, each of which was a perfedl portion of a fphere ; but
each of thefe fpherical parts was inclofed in a partition feparating
* See page 47, of this Tolume.
( 342 )
it from the others, cxliibiting at the parts of reparation a kind of
luminous appearanee, fo that each fpherical part was furrounded by
lix fides, as is fliewn in Jig. 11, A B C D.
When I removed this tunica cornea a little from the focus of the
microfcope, and placed a lighted candle at a fmall dillance, fo that
the light of it mult pals through the tunica cornea, I then faw
through it the llame of tlie candle inverted, and not a fingle one,
but fome hundreds of flames appeared to me, and thefe fo dillind;-
ly (though wonderfully minute) that I could difcern the motion or
trembling in each of them.
Dire6ling my view, through the fame tunica cornea, to the Ree-
pie of our new church, which I have meafured by a quadrant and
found to be two hundred and ninety-nine feet high, and I judge to be
about feven hundred and fifty feet dillant from my lludy, I law the
reprefentation of a great number of minute lleeples inverted, and
which feemed no larger than the point of a needle feen by the na-
ked eye.
When I looked at the neighbouring houfes, I could fee, through
the tunica cornea, not only the buildings, but the doors and win-
dows, and could plainly diftingiufh whether the windows were Ihut
or open.
It mull: be obferved that n\ Jig 11, A B C D, a very fmall part
only of the tunica cornea is reprefented, but to give an idea of the
whole of it, and to fliew the multitudes of the protuberances or
optical organs it contains, every one of which is a perfect eye, I
counted how many of thofe protuberances were contained in the
diameter of the whole tunica cornea, which amounted to about one
hundred ; but if we reckon them to be only ninety, the number of
optical organs in the whole furface of the tunica cornea will amount
to above eight thoufand.
In the fame manner I alfo examined the eyes of a fly, and I per-
ceived the fame perfedion in the formation of the optical organs it
contained (though thefe were fmaller than in the dragon-fly) j and
( 343 )
through every one of them I could moft plainly dillinguilh all
iurrounduig objeds.
Fig. 12, EFG, reprelents a fmall portion of the tunica cornea
in the eye of a fly, in which thofe protuberant parts or optical or-
gans were not fewer in number than in the eye of the dragon-fly.
And to fliew the incredible perfed;ion of each of thefe optical or-
gans, I took a large grain of common fcowering fand, and I mult
fay, that above a thoufand of thofe protuberances, in the eye of a
fly, taken together, were not equal to the fize of that grain of fand.
What I have here faid, refpedling the eye of a fly, mutl alfo be
underflood of the eye of a gnat, regard being had to the compara-
tive fmallnefs of the gnat's eye.
About the time of my making thefe obfervations, I found it af-
ferted in the writings of a certain author, when treating of ants
and moths, that ants have no eyes in their heads, on account of
their fmallnefs; but, meeting with fome ants in my garden, I found,
upon difledling them, that each of their eyes contained fifty optical
organs ; and in the brains of thofe creatures I faw, with admiration,-
the wonderfully minute blood-veflels they contained.
Refuming the examination of the eyes of the dnigon-fly, I was
defirous to know whether the tunica cornea in them confilled of
many fcaly particles laid one on another, as I have in another place
defcribed to be the formation of it in the eyes of men and quadru-
peds. This difledion, after fome difficulty, I accomplilhed ; but I
obferved that the leafl: alteration made by difl'eclion in the tunica
cornea, prevented my diftinguifliing objeds through it: I, however,
difcovered that it was in reality compofed of many particles or
fcales, laid one on another, of which I could diflincily count thir-
teen feries.
Now, if we confider the multitude of parts of which thefe fcales
or flcins mufl: be formed, which efcape our relearches and our fight,
and moreover, how clofely and exactly they muft be laid together,
to give free paflage to the light, we fliall be loll in wonder at fuch
perfedion in the eyes of fuch infignificant creatures as thefe flies :
( 344 )
at the lame time we mull admire the regularity of Nature's works,
all whole operations are performed in liniilar ways, both in the for-
mation of the eyes of thefe minute creatures, and in ihofc of larger
animals, and alfo of the human fpecies.
Now, fince we fee the regularity of the propagation of the mi-
nute marine animal I have been defcribing, and when we contem-
plate the wonderful formation and incomprehenfible perfedlions in
the eyes of flies, and the admirable conllruclion of their many op-
tical organs — when, I fay, tliefe things are known, furely none
will be lb abfurd as to retain the notion that any animal, however
contemptible in our eyes, can be produced fpontaneoully or bred
from corruption.
But I will conclude with this with, that the eyes of all may be
opened to the truth of the regular propagation of all the animals
and vegetables on this earth ; and to admire the infinite wifdom of
the Creator, in the formation of all things at the Beginning, and in
the wonderful and infinitely diverlified provilion made for their pro-
pagation through all fucceeding ages of the world.
END OF THE SECOND VOLUME.
4-
INDEX.
A.
Vol. Fol.
x\CIDS in theftomach, the Author's opinion refpecting
their good or ill qualities I. 154
AIR, the Author's fentiments refpecting condenfed and
rarified Air II. 1 60
the Author's method of extrafting Air from diffe-
rent fluids II. 307
ALDER Wood defcribed II. 3
AMBER, fome pieces prefented to the Author I. 2 1 8
ANIMALCULES, in the fubftance adhering to the teeth I. 118
■ in frelh water, defcribed in a letter
from the Author to Sig. Maghabechi II. 82
in the bloflbms of fruit trees II. 1 80
on the young Ihoots of goofeberry and
currant trees II. 1 gs
'■ in the fediment in gutters on the roofs
of houfes II. 207
ANT, particularly defcribed II. 17
ASH timber, the nature of it, and its different degrees of
goodnefs II. 6
B.
BARK of Trees, how formed II, 131
BEECH Timber, its formation II. 2
A
ii INDEX.
Vol. Fol.
BLOOD, its component parts defcribed I. 89
the formation of its globules examined II. 235
coagulated by bruifes, how difperfed I. 104
its circulation obferved in a cock's comb and gills I. QO
in the earsof white rabbits ib.
in a bat's wing ib.
in a Tadpole I. 91
in the tail of a fmall fifli I. 95
its courfe from the heart in the arteries, and re---^»i-^Ao.
turn by the veins, viewed in the tail of an eel,
and minutely defcribed I. 97
its circulation feen in a crab's foot II. 73
in the tail and fins of an eel,
and feveral other kinds of fifh II. 215
the Author's apparatus for viewing the circu-
lation II. 217
■ the Author's opinion refpedling the frequency
of its courfe from the heart to different parts
of the body II. 321
BONES, their formation II. 129
BOX Wood defcribed. II. 5
BRAIN, in different animals, its texture defcribed .. II. 97
ofagnat II. 71
C.
CANTHARIDES, the fait in them examined II. 286
CEMENTS of different kinds defcribed II. 331
COCOA Tree and its fruit, called the Cocoa Nut, defcribed I. 191
COCHINEAL examined and defcribed I. 213
COFFEE defcribed, and in what its virtues confifts I. 1 2 1
CORN, in granaries, infefted by a maggot I. 25
COTTON, a peculiarity in the Seed of Cotton II. 58
CRYSTALLINE humour of the eye defcribed I. 231
INDEX. iii
E.
Vol. Fol.
EARTH, fome phoenomena in the diurnal motion of the
Earth illuftrated and explained II. 318
EBONY Wood defcribed II. 3
EELS, the manner of their generation defcribed II. 62
in vinegar defcribed I. 1 2 7
ELM Timber, its format! on II. l
EQUIVOCAL, or fpontaneous generation, refuted [. 73
EXCRESCENCE on the leaves of oak, caufed by a mag-
got, w^hich produces the gall-nut. . I. 137
■ — on the leaves of thiftles produced in like
manner I. 142
on the leaf of the Willow II. 'n
EYE, its cryftalhne humour described I. 231
the ftrudlure of it defcribed by Adams I. 242
of a Whale, the Author's remarks on it I. 205
E.
FEATHERS of Birds, their formation I. 271, 279
. on the Vikings of the moth which breeds from
a maggot in corn and on cloths I. 31
, on the wings of a filkworm's moth I. 03
_ . ■ of a large moth I. ill
of a gnat II. 253
FIBRES, the fmall component fibres in the flelh of ani-
mals examined by the microfcope II. 113
in the bodies of fifh examined II, 1 lO
in the flefliy part of a flea II 1 1 9
. ■ in the flefli of a moufe . . II. 120
FIR Timber, its different degrees of goodnefs I. 9
its veflels particularly defcribed I. 10
FISH, their age to be afcertained by the examination of
their fcales I. 69
iv INDEX.
Vol. Fol.
FISH, the Author's opinion refpefting their longevity. . I. 70
an extraordinary quantity on the lea-coall, near
Delft, accounted for by the Author I. 1'83
a minute Ihell-fifli, adhering to the ftiells of other
filh, minutely defcribed II. 339
FLEA, minutely defcribed II. 33
how to prevent its increafe II. 30
FLY, its generation and rapid increafe II. 25 7
two fpecies of a minute Fly defcribed II. 1 90, 19 1
FROGS, their generation II. 22;
G.
GALL Nut, an excrefcence on the leaf of the oak, the man-
ner of its prod udlion I. 137
GNAT, the rting of the Gnat particularly defcribed II. 2-iQ
its wing, and the feathers on it defcribed II. 254
the brain of one II. 71
GOUT, the calcareous fubllance formed in the limbs of
gouty perfons examined II. ]S3
its cure by Moxa, as practifed by the Chinefe . . II. 137
GUNPOWDER, various obfervations by the Author on
its nature and properties II. 1 5 1
H.
HAIR, Its formation 1.271,282
HAIRS oa the feet of flies and crabs particularly examin-
ed and defcribed II. 71, 72
HEART, the formation of it in feveral animals I. 258
HERRING, various obfervations on this fifli II. 9
HOPS defcribed, and wherein their virtue confills I. 207
I-
LIME Tree, the formation of this wood defcribed II. 5
and other cements examined and defcribed II. 331
INDEX. V
Vol. Fol.
LOADSTONE, or Magnet, defcribed II. go
LOCUSTS, the Author's fentiments relpeding them. . . . II. 179
LOUSE, particularly defcribed II. 103
M.
MACE, wherein its virtue confills, and on damaged Mace I. 299
MAGGOT infefting corn in granaries, produced by a
Moth, a particular delcription of it I. 25
' how to dellroy this Moth I. 29
found in the bloflbms of fruit trees II. 180
bred in cheefe, and found in a tooth I. 119
which feeds on the grals in meadows II. 174
which feeds on wood II. 335
MAGNET, or Loadftone, various obfervations on it . . . II. 90
MICROSCOPES, Mr. Leeuwenhoek's Microfcopes de-
fcribed II. 220
MILLEPEDAINDICA, a noxiouslndian reptile defcribed II. 31
MITE, particularly defcribed II. 170
MOXA, ufed by the Chinefe in the cure of the Gout ... II. 137
the manner of adminiftering it, as defcribed by
Sir William Temple II. J 39
MUSCLE, the fea mufcle defcribed I. 73
the frefli- water mufcle defcribed I. 85
N.
NEGROES, the blacknefs of their Ikin how caufed II. 1 2(3
NERVES, their formation defcribed II. 303
NETTLE, the nature of its fting defcribed IL 263
NUTMEGS, and the tree producing them defcribed I. 287
O.
OAK Timber, the manner of its formation and growth . . I, 1
■ the different degrees of goodnefs in it . . . I. 4
B
vi INDEX. .
Vol. Fol.
OAR Timber, the manner of preparing it to make pipe
leaves for ca(ks II. 7
OPTICAL ORGANS, in the eye of a filk- worm's moth I. Ol
in the eye of a beetle II. 05
in the eye of a flirimp II. 268
OPTIC NERVES, in the eye of a large fly II. 08
P. •
PAREI R A BR AVA, its root examined I. 224
PAPER, burnt, a fubftance refembling it, found to be a
vegetable production I. 218
PEAT, the nature of that fubftance I. 145
PEPPER, the nature of it examined . .., II. 277
PERIWINKLE, the herb, examined I. 221
PERSPIRATION, infenfible, the Author's obfervations
refped;ing it II. 255
PHOSPHORLTS, its appearance examined and defcribed . II. 242
POISON of the Viper, as defcribed by Dr. Mead, com-
pared with that of the Scorpion. . ; . . I. 13 i
how emitted by different animals I. 167
a.
QUILLS, their formation I. 271
R.
RUNNET, its nature and properties I. 154
RUSHES, their formation II. 298
S.
SAGE, wherein its virtue confifts I. 1 05
SCALES, on the Ikin of the human body defcribed II. 121
of fifhes, how formed . . .' I. 05
a means of difcovering their age I. O9
SCORPION defcribed L 129
INDEX. vii
Vol. Fol.
SEA, its prefliire at great depths confldered I, 267
the Author's opinion relpe6ling its gradual eleva-
tion in refpeft of the land I. 1 5 i
SEEDS of feveral trees examined and defcribed II. 47
in figs and llrawberries II. 108
• the young plant difcernible in feeds II. 28g
SHRIMP defcribed ' II. 266
SILK-WORM defcribed I. 49
SNAl L, or animalcule found on the Vine I. 1 Ol
SPIDER defcribed I. 35
STING of the Scorpion defcribed I. 1 30
of the Gnat II. 249
of the Horfe-fly II. 252
I of the common Nettle II. 263
STONES in the bladder, the nature of them II. 143
T.
TADPOLE defcribed IL 230
TEA, its nature and properties confidered II. 281
TEETH, their formation I. 113
■ '■ their decay accounted for I. nQ
TDIBER, the queliion confidered as to the beft feafon
for felling it .... I. 7
TOBACCO Seed defcribed H. 294
TONGUE, its mufcular fibres defcribed I. 255
V.
VINEGAR, its fliarpnefs caufed by the falts it contains I 126
~ Eels in it defcribed L 127
W.
WEEVIL, or Corn-beetle, defcribed I. 17
how to preferve corn from it I. 22
WHALE, various obfervations refpctling one I. 205
viii INDEX.
Vol. Fol.
WHEAT, its vegetation and component parts minutely
delcribed I. 1O9
WILLOW, its wood delcribed II. 2
, its feed, and the manner of its vegetation . . II. 53
WOOL, its formation .- I. 277
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