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DISSERTATIONS

RELATIVE TO THE

°" /'

NATURAL HISTORY

ANIMALS AND VEGETABLES.

TRANSLATED FROM THE ITALIAN OF THE

ABBE SPALLANZANI,

Royal Profeflbr of Natural Hiftory in the Univerfity of
Pavia, Superintendent of the Public Museum, and
F£LLov7 of various learned Societies.

In TWO VOLUMES.
A NEW EDITION CORRECTED AND ENLARGED.

VOL II.

LONDON:

printed for J. MURRAY, KO. 32, FLEET-STREET j
M DCC LXXXIX.

INTRODUCTION.

IN the iirft and fecond Differtations of this
volume, I fulfil in part the promife I had
long fince made in my ProfpeBus concerning
Animal Re^produBionSy in which I announced
my difcovery of the pre-exiftence of the germ,
in one fpecies of frog. This difcovery is re-
lated at length in the firft differtation. That
fo long a fpace of time has elapfed fince the
obfervation was made, I confider as a very
fortunate circumftance ; for, having exami^
ned other animals, and having found that the
fame thing is true with refped: to them, I
have ftill ftronger reafor^ for prefuming, that
the exiftence of the germ in the female before
fecundation, is one of the mod general laws
of nature. While we are in quefl: of one
truth, it generally happens that others ofi?er
themfelves as it were fpontaneoufly. Ac-
cordingly I have been led by the obfervations,
which iliew the pre-exiftence of the germ,
.Vol. II. B to

to difcover that an order of animals, con-
fidered by naturalifts as oviparous, is in re-
ality viviparous.

The fubjed; of my fecond differ tation is the
artificial fecundation of various animals, of
which the firft lines maybe feen in the fame
profped;us. This v^as accomplifhed by means
of the feminal liquor of the animals them-
felves ; and I have fucceeded as well, as if the
male himfelf had performed his proper func-
tion.

The clofe analogy between animals and ve-
getables, induced me to enquire, whether the
embryos of plants exiftin like manner in the
avarium before fecundation. From the third
differtation it will appear that this is really
the cafe. Thefe enquiries have alfo convin-
ced me, that the fecundating duft is not fo
abfolutely neceffary as botanifts in general
fuppofe.

The fame analogy ought, perhaps, to have
led rue to attempt the artificial fecundation of
plants ; for, though feveral have undertaken
fuch experiments, and fucceeded in them, I
know not whether any one has done this with
truly philofophical views, and in order to
difcover the manner of thi^ wonderful ope-
ration. To confefs the truth, I would not
have avoided this talK if engagements of

anothei

[ iii ]

another nature had not prevented me. I have,
however, exhorted others to undertake it, and *
at the fame time have propofed fome views
that may fliew the way to fuccefs.

It is faid by many, that fecundation is
among the myfteries of nature^ and, hke
many of her operations, an objedl of admira-
tion, rather than of enquiry. Such an opi-
nion is highly agreeable to the idlenefs of
man. In times pall, I acknowledge that ge-
neration, both in animals and plants, was
involved in darknefs, impenetrable to the hu-
man eye; but, fince the appearance of Hal-
ler and Bonnet, thr3 gloom has been rendered
much lefs thick. I am very far from think-
ing that I have diffipated it entirely, yet I
v^ould fain hope that, by my efforts, it has
been fomew^hat cleared, and that a light, lefs
feeble and uncertain, now fhines through it.
The following differtations wdll enable the
learned reader to judge whether this opinion
is well founded, or merely the offspring of
felf-love. . <

B 2 D I S g E R-.

DISSERTATION

CONCERNING THE

GENERATION

OF

CERTAIN ANIMALS.

CHAP. L

GENERATION OF THE GREEN AQUATIC

FROG,

I. nPHUS I chufe to denominate the frog
^ in queftion, from the green hue of
the upper part of its body, and from its Hving
in water, particularly in puddles and ditches,
whereas other fpecies live on dry land and
trees ; but of thefe laft I fliall have. Qccafion
Xo fpeak afterwards.

II. The head of the male is furniflied with
two membranous veficles, w^hich are very
much dilated when the animal -croaks. The
great toe of the fore foot has a flefhy promi-
nence, which becomes very perceptible at the

B 3 feafou

6 DISSERTATION I.

feafon of their amours : the female is deftitute
of thefe parts, and has the back and thighs
marked with black fpots, which are feldom
viable in the male.

III. This fpecies is not to be confounded
with that called by Roefel rana vin'Ss aqua^
tica. A glance of his beautiful colpured fi-
gures, will be fufficient to fliew that they are
totally diftindl. His exceeds all other frogs
in iize^ mine is the fmalleft of all, and is
fcarce one-third fo large as RoefeFsj befides
his has three yellow ftripes pn the back and
fides, which in mine are totally wanting {a) .

IV. The amours of this fpecies begin in
April, and end in May; they are, however,
influenced by the temperature of the atmo-
fphere; during their continuance the males
maintain an inceffant croaking. In autumn
and winter the immature eggs lie all in the
ovarium, which is divided into two lobes;
thefe lobes confift of leffer lobes, each of
which is invefled with a peculiar membrane.
The eggs are of two fizes ; fome very fmall,
fo as to be fcarce vifible by the naked eye;
others feven or eight times larger; both

{a) This efiential difference was flill more apparent when I
came to compare mine with feme of Roefel 's, brought me by
the fifliermen.

kinds

DISSERTATION I. 7

kinds are globular. The frnaller are of a livid
grey coloiit' ; of the larger one hemifphere is
white, and the other black. The flightell
touch is fufficient to burft them, after which
they are refolyed into a cineritxous vifcid li-
quor.

V. The ovarium of this, as well as many-
other fpecies, appears to be externally covered
with black points, which have been the
fource of a memorable miftake^ for Vaiiif-
neri (a), and other celebrated naturalifts, have
fuppofed them to be the rudiments of the
tadpole. The error arofe from their being
contented with firft appearances, and fearch**"
ing no further; for the fpots lying clofe to
the eggs, might eafily induce the obferver to
believe that they form part of them, and are
therefore fo many felufes. But the matter
is cleared up by the following experiments ;
I . When the common membrane is removed,
thefe points ftill adhere to it. 2. And if the
eggs are infpefted one by one, both externally
and internally^ no veftige of this black fpot
can be perceived. If the membrane of the
ovarium be exarnined by the mifcrofcope, it
will then be (ccn that thefe points are black

{a) Opere fifico-mediclie, T« i. OiTervazioni intorno
k fane 5

^ 4 fpot^

^ BISSERTATION

I.

fpots of an irregular fliape. They are not
peculiar to this membrane, for they are found
in the area of the mefentery, and upon the
heart.

VI. If the eggs be again examined in
fpring, we fhall ftill find them in the ova-
rium, but confiderably enlarged 5 (thofe I
mean of the larger fize, iv). and they vv^ill
be found to be mature, v^hen the male is
coupled with the female. The individuals of
this fpecies couple exactly hke thofe obferved
by Swammerdam and Roefel {a). The male
climbs upon the back of the female, and
palling his fore legs under her axilla, brings
them to meet upon the breaft, and there clafp-
ing his fingers, holds her clofe, till flie has
difcharged all her eggs. The duration of
this procefs is inverfely proportional to the
warmth of the atmoiphere. When this is
confiderable, the female will be at liberty in
five or fix days ; but in i cold feafon, the em-
braces of the male continue for eight or nine
days. This I learned by putting frogs in
large veffels full of water, when their amours
were about to commence, and confining
them till they had difcharged their eggs.
And, although Vallifneri afl^erts, upon the

(a) Biblia Naturaa, Hift. Nat. Ranar.

authority

PISSERTATION I. 9

aathority of a fingle experiment, that frogs
do not difcharge their eggs in clofe veffels, it
is certain that numberlefs fads prove the con-
trary, as I, and, before me, Svvammerdam
and Roefel have found.

VII. It is true, as he aiTerts in another
place, that this does not happen when the
female is kept conflantly feparate from the
male. I fay confiantly , for if they be pulled
afunder when the eees are defcended into the
cavity of the uterus, they will be difcharged,
though the female is kept feparate, but they
will be ban-en.

VIII. If the fituation of the eggs, at the
time of copulation, be examined, during the
firft days they will be found in the fac of the
ovarium^ and, during the fucceeding, partly
in the ovarium, and partly in the oviducts,
and at laft all in the uterus, except the fmall
ones, which remain attached to the ovarium.
The eggs, when in the ovarium, are fmaller
than when in the ovidufts and uterus. In
thefe fituations they are enveloped with that
vifcid tranfparent mucilage, which is impro-
perly Q'2i^tA frog s f pawn,

IX. Of the various trials I have made, in
cjder to afcertain w^hether eggs taken from
the ovarium, the ovidudi, and the uterus,
when the jiiak is embracing the female,

would

lO DISSERTATION I.

would be prolific, I muft own that not one
has fucceeded. As this is a point of extreme
importance, I repeated my experiments to
latiety; and in my journals I find, that 1 have
opened one hundred and fiftyr-fix females
v/hile they were embraced by the male, of
not one of wKich did the eggs ever bring
foith young, though I immediately placed
them in watery whereas thofe that were ex-
cluded fpontaneoufly by the female, were
all prolific. I have even taken further pains.
The difcharge of eggs lails about an hour;
during this procefs I killed a female, and put
the eggs that remained in the body in the
water into which thofe difcharged by the
animal fell ; but the latter produced tadpoles,
while the former became an offenfive putrid
mafs. From thefe fad:s I concluded, that the
fecundation of the eggs does not take place
within, but without the body; whence it
appears how farLinnseus was miflaken, when
he pronounced, in his ufual decifive tone^^
** Nollam in rerum natura, in ullo vivente
corpore fieri fecundationem vel oyi impreg-
nationem extra corpus matris (^).''

X. Hence we like wife fee the faifehood of
the ftrange opinion of profeffor Menzius,

{a) See Artedls Ichthyology, part ii. p. 32.

who

DISSERTATION I. II

who fuppofed that, while the male embraces
the female fo clofely, the feed is emitted from
the flefhy prominence of the toe, and paffing
through many windings unknown to us, pe-
netrates into the thorax, and there impreg-
nates the eggs [a).

XI. But if in this fpecies fecundation takes
place out of the body of the female, ihall. we
fuppofe that the male ejects his femen upon
the eggs as they are difcharged {&) ? This,
with refpscl to other fpecies, is the opinion
of Swammerdam, and adopted by Roefel;
though he afterwards fays, that he cannot de-
termine v/hether the eggs in the uterus are
impregnated by the femen emitted out of the
body bat afterwards arriving at them. To
clear up this point, I have paid unremitting
attention to every phenomenon. As foon as
the eggs begin to be difcharged, the agitation
of the female is extreme ; fhe darts backwards
and forwards, rifes towards the furface of the
water, and then fmks, keepiiig the hind legs
conftantly ftretched out, and croaking in a
iow voice. The male keeping his hind legs
clofe to his body, throws himfelf into ftrange

(a) Generatio Trapa ^g|o; in rana confpicua.
(^) In the frog, toad, newt, and feveral other animals, the
eggs are difcharged at the extremity of the alimentary canal.

contortions,

j2 DISSERTATION 1.

contortions, and accompanies the croaking
of the female with a kind of interrupted noife,
which I cannot exprefs by words. I more-
over obferved, that an obtufe tumid point,
¥/hich 1 fufpe6led to be the penis, was elon-
gated, and now and then brought towards the
eggs neareft the vent; but I could not per-
ceive any emiffion from this fuppofed penis.
The femen, however, might be in fuch fmall
quantity, or fo trapfparent, as not to be vi-

fible.

XII. To determine the queftion, I placed
fome couples, of which the female w^as be-
ginning to difcharge her eggs, in empty vef-
fels. As I knew that in thefe amphibious
animals fecundation always takes place in
water, my hopes from this expedient were not
very fanguine; but fortune v/as more propiti-'
ous than I could have expedled. The male is
fo much attached to the female, that, not-
withftanding he is taken out of his natural
element, he perfifts in performing his office.
I nov/ faw that there darted a fmall jet of
limpid liquor from the tumid point in the
vicinity of the anus, upon the eggs hanging
out at the vent of the female. This pheno-
menon took place only at intervals, the ft-
fiiale from time to time difcontinuing the
^ifcharge of eggs, and the male the emiffioa

of

DISSERTATION 1. Ij

of femen* I was an eye-witnefs of this cu-
rious fcene in feven couples of frogs taken out
of the water ; it did not entirely ceafe, till all
the eggs were expelled from the uterus. The
eggs being afterwards put into water, and
bringing forth young, I hefitated not to fup-
pofe, that the liquor emitted by the male was
real femen; as I afterwards found, by dif-
covering it in the veficulse feminales, and
afcertaining the point to be the penis.

XIII. The abbe Nollet, in a letter dated
nine years ago, alluding to the hint in my
profped:us, of my difcovery of the exiftence
of the tadpole before fecundation, expreiTes
himfelf in this manner: ^* What you fay of
the exiftence of the tadpole, before we can
perceive any adl of fecundation, has particu-
larly ftruck me. About thirty years ago, Mr.
Reaumur and myfelf made many refearches
relative to this fubjeit. We attended for
weeks very diligently and patiently, to what
paffed while the male embraced the female*
I remember putting breeches of w^axed taf-
fety on the male, and w^atching a long time,
without perceiving any appearance that de-
noted an ad: of fecundation.*'

I v/ill not here ftop to enquire by what fa-
tality it happened, that two naturaliits, fo
inteliigent and attentive, failed in their en-

quiries^

14 t>ISSERTATION I.

quirles. The idea of the breeches, however
v/himfical and ridiculous it may appear, did
not difpleafe me, and I refolved to put it in
prad:ice. The males, notwithftanding this
incumbrance, feek the females with equal
eagernefs, and perform^ as well as they can,
the act of generation ; but the event is fuch
as may be expected : the eggs are never pro-
lific, for want of having been bedewed with
femen, which fometimes may be feen in the
breeches in the form of drops. That thefe
drops are real feed, appeared clearly from the
artificial fecundation that was obtained by
means of them (a).

XIV. Having difcovered every thing re-
lative to the fituation and manner of impreg-
nation, my next bufinefs was to obferve the
eggs, till the young animal fhould appear.
The eggs lie in the centre of a white muci-
lage, which confifts of tranfparent fpherical
maffes connecfled together. Round the egg
are two concentrical membranes^, of which
the innermoft, when pierced with a needle,
difcharges a fluid as^ limpid as water. The
egg is round, andhas a fmooth furface, of
which one hemifphere is black, and the other
white. This is feen at Fig. i. Plate L
No III. jQiews 'fifteen eggs, with their mu-

(a) See Differtation vui.

cilage ;

DISSERTATION I. I5

cilasre : each lies in the midft of a circle,
made by thefe membranes. To fee the other
membrane clearly, the gluten mull be mag-
nified as at N° II. C is the external, B the
internal membrane, and D the gluten.

XV. When the hot feafon is far advanced,
the obferver foon perceives the lineaments of
the tadpole. The egg grows for fome hours
without lofing its round ihape, it is next e-
longatedj the white hemifphere becomes
darker, and the black changes into a longi-
tudinal furrow, terminated by two perpendi-
cular proceffes. And as it increafes as welL
in bulk as length, the internal circular mem-
brane is dilated, and contains more fluid.
Compare N° I. fig. 2. with N° II. fig. i.

By tracing thus the progrefs of evolution^
we come to perceive that thefe bodies are not
eggs, as Naturalifts fuppofe, but real tadpoles.
The furrow and the procefles become lon^«;r ;
the fuppofed egg afiTumes a pointed figure ; the
whitifh hemifphere dilates, and the black is
incurvated. The pointed part appears to be
the tail of the tadpole, and the other the bo-
dy. Further, the oppofite end takes on tne
appearance of the head, in the fore part of
which the form of the eyes is vifible, though
they are yet clofed. The two proceffes airo,
bv which the animal fallens, himfelf to the

frnoG theft

l6 DISSERTATION I.

fmootheft bodies, when it is tired of fwim-*
ming, become evident, as likewife the vef-
tige of the aperture of the mouth, and the ru-
diments of the gills.

XVI. At firil the tadpole does not fhew
any iigns of animation, w^hen touched with
a needle, or fuddenly expofed to the rays of
the fun, even when concentrated in the focus
of a lens, he does not become fenlible to
thefe impreffions, till his organs are further
unfolded: he then gradually begins to move
and loofen his fetters: at this time it appears
clearly, that the internal circular membrane
is the amnion, in the liquor of which the
tadpole floats ; the umbilical chord at laft is
feen, and becomes ftill more perceptible,
the iirft day after the animal has quitted his
confinement. The cord is not, as in other
animals, attached to the belly, but to the re-
gion of the head. A tadpole at the begin-
ning of its evolution, is reprefented at N^ II,
fig. 2. and N° III. fig. i . in which at E appear
the little gills. At N' III. fig. 2. is a tad-
pole, magnified with its back turned towards
the obferver. In that at N*" III. fig. 3. and
thofe N** IV. is {qqh the veftige of the eyes,
and the umbilical cord coming out from be-
low the mouth,

?:vii.

DISSERTATION I. 1 7

XVII. The reader will probably be furpri-
^ed at this defcription, fince it appears, that
the tadpole does not come out of the egg, but
that the egg is tranfmuted into a tadpole ; or,
to fpeak more philofophically, that the egg is
nothing but the tadpole wrapped up and con-
centrated, being evolved in confequence of
fecundation, and affuming the lineaments of
an animal, Thefe phaenomena were nev/ and
unexpedied, for I was firmly perfuaded, that
the globules of two colours, furrounded by
mucus, were real eggs ; all who have written
concerning the generation of frogs, as Jaco-
beus, Valifneri, and Roefel, having fo deno-
minated them. But as greater deference v/as
due to what nature fhewed fo plainly, than to
the authority of the moft celebrated v/riters,
it is fit to call thefe globules tadpoles or fetu-
fes inftead of eggs ; for it is improper to name
any body an egg, which, however clofely it
may refemble one, takes the fhape of an ani-
mal without leaving any fliell, as is the cafe
with all animals that come from an egg.

XVI II. But fit v/as of importance to ex-
amine thefe globules by experiment before fe-
cundation, as alfo while they were yet in the
uterus. Upon the moil rigorous and exad:
comparifon it appeared, not only that the
fpheres of mucus exa^ftly refemble each other

Vol. IL C in

1 8 I^ISSERTAttON i.

in fize and nature, and the two membranes
with refpe(fl to their pofition, fliape and co-
lour$ but that the unimpregnated globules
are not by any means diflinguifliable from the
impregnated ones. Upon feparating the mu-
cus and the two membranes, they appear to
be aUke fpotted with white and black, which
colours remain in fome meafure when the evo-
lution of the tadpole is complete. The per-
fed: fimilitude, as well external as internal, is
very ftriking. If a globule be pierced with a
needle, either before or after fecundation^ a
femifluid yellowifh white fubftance oozes
- out : if the aperture be enlarged, the whole
internal capacity appears to be filled with this
fubftance, which lofes its fluidity as the tad-
pole is evolved, every day acquiring greater
confiftenCe. If the globules before or a lit-
tle after they come out of the uterus be put
into fpirit of wine or vinegar, or be boiled> and
then ftripped of their pellicles, we fhall find
fo many indurated maffes, which when cut
through appear to be homogeneous. If we
next proceed to examine the external parts,
the pellicle before fecundation is thin and
tranfparent, properties which it retains when
fecundation has taken place. Afterwards,
indeed, as the tadpole is evolved, it enlarges
and thickens juft as the Ikin of other animals

erov/s

DISSCRTATION I. I9

grows with their growth. As the pelHcle is
made to adhere to the infide of the unimpreg-
nated p-lobule by heat or vinegar, fo it con-
tinues to adhere after fecundation; and it ad-
heres more and more firmly as the globules
lofe their fhape, and acquire that of the
tadpole.

XIX. Hence the identity between the im-
pregnated and unimpregnated globules is ma-
nifeffc. But the former are nothing but fe-
tufes of the frog, therefore the latter muft be
fo too, and confequently the fetus exifts in
this fpecies before the male performs the of-
fice of fecundation. Hence v/e are led to
other confequences of no lefs importance,
I . As thefe fuppofed eggs exifted in the ova-
rium before their defcent through the ovidudls
into the uterus, and long before fecundation
(iv, VI 11), the fetus exifted in the mother's
body long before fecundation. 2. Although
the evolution of thefe fetufes is never fo con-
fiderable and quick, as after fecundation, it
is, however, perceptible before -, for let it be
confidered, that the fetufes in the uterus are
above fixty times larger than they were a year
before, when they adhered to the ovarium, as
I have found by comparing them.. 3. Befides
the fetus, the amnion and umbilical cord
exift before fecundation.

C2 CHAP.

20 DISSERTATION I.

CHAP. IL

GENERATION OF THE TREE-FROG.

XX.TN this and the following chapters, I
-^ ihall be brief: I iliall only make a
few additions to Roefel's account, and notice
fome miftakes into which he has fallen, in
order to comfrleat the hiftory of the animals.

The tree-frog is of very fmall iize. The
back is of a very beautiful green colour. A
vifcid juice, that oozes out from its feet,
enables it to failen itfelfto the fmoo theft bo-
dies. In fummer, it fixes its abode upon
trees, in the fpring, it defcends and repairs
to ftagnant water, in order to propagate the
fpecies.

XXI. Though the male mounts upon the
back of the female, and embraces her very
clofely, he does not, like the green aquatic
frog, throw his arms round her thorax, but
faftens his hands undler her axilla?. Hence the
females efcape thofe accidents that happen to
the females of other fpecies, which are often
killed before parturition, by the violent com-
prefiion of the. male, as appears from the con-
tufions and lacerations upon the breaft.

XXII. This

DISSERTATION I. 21

XXI I . This fpecies continues coupled feme-
times, according to Roefel, three whole days,
thoueh at others it is finifhed in one day.
Thofe which I obierved did not continue to-
gether above a few hours. Thi^ difference I
attribute to the warmer temperature of our
climate, which occalions more fpeedy par-
turition.

XXIII. The fame naturalift obferves, that
during copulation, the female plunges at in-
tervals into the water, and reinains imm^erfed
fome time : during which, the male approxi-
mates the extremity of his body to that of
the body of the female, and that this m^otioa
is always performed with greater brifknefs,
v/hile the eggs are coming forth. Ke con--
feffes that he could never, with all his atten-
tion, perceive the part that characterifes the
male, nor any liquor emitted for the fecun-
dation of the eo^gs.

XXIV. Though I could never dlfcover any
protuberance or papilla, w^hich I could fup-
pofe to be the penis, yet by taking the ani^
mals out of v.^ater (xii), I have been able to
throw further light on this point. I obferved,
that about half an hour before any eggs are
difcharged, the ardour of the male became
jextreme. He v/ould frequently ilretch cut
the pofterior part of his bodv, and then bring

C3 ' it

22 DISSERTATION I.

it into contad with that of the female. He.
would then remove it, and foon apply it
•again. Thefe motions became more frequent
when the eggs began to be difcharged : and
continued as long as that procefs lafted.

XXV. In the mean time, I could not per-
ceive any emiilion of femen ; but upon lifting
up the hind part of the male, I faw a tranf-
parent liquor ejedled from the anus at inter-
vals, which I readily concluded to be the fe-
men. When I made ufe of the breeches
(xiii), the eggs never produced tadpoles:
and the breeches were wetted with femen as
before (xiiij.

XXVI. Are the eggs in this fpecies alfo im-
pregnated only after they are difcharged.? I
obferved a flight variation in the prefent cafe.
Thofe which are nearefl the vent, are fome-
times impregnated before they are difcharged.
But the Angularity of the phenomenon re-
Guires that I fhould be a little more explicit.
lloefel juftly obferves, that in the female of
this fpecies, the eggs defcend into the uterus
before ihe is embraced by the male ; if they
are now taken out, and fet in w^ater, they all
putrefy. This alfo happens if they are taken
out after they are coupled, but before the fe-
male has begun to difcharge any eggs. But
wjtien the difcharge has commenced, if the

* female

DISSERTATION !• 2^

female be opened, and the eggs of the uterus,
and thcfe near the vent, are put into feparate
vellels of water, feveral of the latter will
fometimes be found to be produ<£live, whereas
all the former will fpoil. This is a clear
proof, that the fem'en fometimes penetrates
a little way into the body, whether it is
thrown fo far by the male, or rather becaufe
the eggs already fecundated, after their dif-^
charge, are fom.etimes retra6led, when the
female is unexpectedly feized by the obferver,
and ceafes to expel any more,

XXV I I , The eggs are fmall in proportion to
the fize of this fpecies : one hemifphere is
yellow and the other black : when they are
taken out of the oviducls or uterus, they are
enveloped in gluten, which circumftance has
unaccountably efcaped the obfervation of
Roefel, who afferts, that the gluten is not
vilible till the eggs have lain twelve hours in
water.

XXVIII. Every egg is furrounded by a fphere
of mucilage, as in No, i^ ii, iii> of fig, 5,
pi. I. The fphere and egg undergo the fol-
lowing changes in water. They increafe in
bulk, and at the fame time the latter is elour
gated, and preiTes againft a circular mem-
brane, which lies within the mucus and fcon
pierces it 5 as the elongation increafes, the

C4 ' ^9!^

24 DISSERTATION !•

hole is enlarged, till at laft the membrane is
divided into two concave fegments: within
which appears a fecond circular membrane,
of much finer confiftence, and of courfe lefs;
apt to ftrike the eye. This membrane, when
it is broken, emits a quantity of liquor, and
is no other than the amnion of the tadpole, as
afterwards more plainly appears. Mean-
while the two fegments feparate entirely, or
at leaft cohere but at a fevv^ points, and part
from the amnion without growing any more ;
but the am.nion becomes thicker, and many
times larger than it was at firft; as alfo does
the egg, on the growth of which depends that
of the membrane. The gradual enlargement
is as follows :

XXIX. When it has become fomewhat
longer and bigger, one extremity thickens,
and the other becomes finer. While the ob-
ferver is intent on thefe changes, he is fur-
prized with the motion of the egg ; it fome-
times turns round, now and then writhes it-
felf, fometimes it brings together its two ex-:
tremities, and then ftretches itfelf and returns
to its original pofition. To thefe unepcpec-
ted appearances another equally unexpedled
iucceeds: from the larger end there fprout
two proceffes and fuggeft the idea of the pro-
tuberances, by means of which the tadpole

at-

DISSERTATION I. 2;^

attaches itfelf to bodies (xv) ; above thefe apr
pear two tumours, which bring to the mind
the idea qf eyes ; and eyes appear diftindtly in
a day or two, and it then becomes neceffary to
fubftitute the notion of a tadpole in the place
of that of an egg. Let the reader caft his.
eye on No. iv. Fig. 5. and he will fee a
fphere of mucus, the inclofed mem^brane and
the tadpole not yet evolved. No. i, ji, m.
Fig. 6. reprefents the membrane dividinp- into
two fegments, which when they are entirely
parted, leave the tadpole No. iv. at liberty,
which appears bent No. vi. Meanwhile
the amnion is feen in the dotted circle i.
full of liquor, in which the tadpole floats.
The two fegments are ftill plainer at Fig.
7. where tv^o amnions are feQn diftinffly, one
of which is entirely feparated from the feg-
ments.

XXX. But do thefe tadpoles exifi: before fe-»
cundation as in the foregoing fpecies ? To
determine this queflicn, I had only to make a
rigorous comparifon between the fuppofed
eggs, after and before impregnation, and I
analyfed them in the fame exact and careful
manner as I had the others (xviii), and found
themoft perfed: refemblance between them;
whence it was neceffary to conclude, that the

fetus

aS DISSERTATION I.

fetus exifts in the female of this fpecies alfc?
before impregnation,

xx:xi. Thefe fetufes are rnore and more
evolved, though ftill inclofed in the amnion,
where they continue longer than thofe of the
green aquatic frog; the time is commonly fix
or feven days ; then the rudiments of the gills
begin to fhoot. At iirft they fvvim flo\Yly,
but as their limbs acquire greater ftrength
and vigour, their motions become brifker.
Fig. 8. reprefents two tadpoles at the time of
quitting the amnion, magnified by the mi~
crofcope: their gills are feen at A A.

XXXII. Upon comparing thefe obfervar
tions with thofe of Roefel, I cannot but dif-
fent from him. The fum of what he fays on
the generation of the tadpoles of the tree-
frog is as follows.

XXXIII. At firft the impregnated eggs
grow in bulk only; then the tadpoles, which
now feem to confift chiefly of belly, though
the head and tail may be clearly difcerned,
appear diftinclly. Every tadpole floats in
the white of the egg (the mucilage that fur-
rounds it XXVI II ). The belly is form^ed by
the yolk, fo the author calls that which h
generally denominated the egg. At the tail
appears a veficle, and afterv/ards another
(from his figures thefe feem to be the two

DISSERTATION I. 27

fegments XXVII i) ; thefe veficles then fepa-
rate, and one remains at the head and the
other at the tail. Roefel conje&ires, that
the tadpole being now endowed with motion
and hfe, takes its nourifhment from the ve-
licle at its head, but he confeffes that he does
not know the ufe of the other,

XXXIV. Though it is true, that the tad-
pole has at firft a large belly, it is falfe, or at
Jeaft a very improper expreflion to fay, that
the belly is chiefly formed of the yolk, fmce
the yolk is the animal itfeif (xxix) ; it would
not be lefs abfurd to fay, that the belly of an
animal coniifts of the animal itfeif.

XXXV. His defcription of the appearance
of the two veiicles, fhews that he did not
make his obfervations wdth fufficient atten-
tion : he probably obferved at intervals ; other-
wife he liiuft have perceived that they were
originally a fphere, w^hich is divided into
tvv^o fegments by the efforts of the tadpole;
confequently they did not appear one after
the other, but both exifted at the fame time
(xxviii)-

xxxvi. If he had taken them up with a
forceps, he would have found, that they
cannot be fuppofed to nourifh th^e tadpole,
for as foon as they appear, which is vv^hen the

■ - iphere

28 DISSERTATION 1.

fphere is divided, they may be removed v^ith-'
out injury to the young animal.

XXXVII. The part really neceffary to this
animal, and of which the removal is fatal,
is the amnion, v^ithin the liquor of which
it at firft floats (xxviii, xxxi). As Roefel
does not mention the amnion, it muft have
been unknown to him ^ and although this
membrane is found in every fpecies of frog
and toad, not the leaft mention is made
of it in his hiftory^ this circumftance the
more furprized me, fince it did not efcape
the dilipence of Swammerdam, in whofe
footileps the German naturalift profelTes to

tread, ' ' ■

xxxviii. He has, however, remarked
an accident, v/hich happens to tadpoles that
die in the amnion, or as he expreffes it to
eggs, that are not prolific: they become
fometimes pointed, fometimes pear-fhaped,
ibmetimxcs oblong, and at others narrow in
the middle, and fo on. Four fuch tadpoles
are reprefented in Fig. 5. at A B C D,

' xxxix. The tadpoles of this fpecies re-
quire great attention. They muft be kept,
not merely in clean water, but in that
which is taken from the places where the
males and females meet, as from ditches

and

DISSERTATION t, 29

and puddles (xx). This precaution was
not abfolutely neceffary for other frogs and
toads; fpring water being fufficient in thefe
cafes.

CHAP.

33 BlSSERtAXION i;

CHAP. III.

GENERATION OF THE TOAD, DENOMl-
NATED BYRo£SEL, BuFO TERRESTRIS
DORSO TUBERCULIS EXASPERATC), OCU«
LIS RUBRIS.

XL. T^ H O U G H Roefd mentions but
^ one fpecieg of this ugly and dif-
gufting animal, 1 incline to believe^ that in
this country there are two; this opinion is
founded on a difference in the external con-
figuration; not to mention a difference in
colour, fome having their backs and fides of
a light cineritious hue, with tubercles of a
tan colour, and others of a pale green^ with
tubercles of a dark red. But notwithftand-
ing this difference, I fhall fpeak of them as
one fpecies, for in what relates to generation^
there is the moft perfect fimilitude.

XL I . Of the whole clafs of frogs and toads^
wdth which I am acquainted, none begin
their amours fo foon as the fpecies in quef-
tion : they are found coupled in the begin-
ning of March, and fometimes in Febmaiy,
before all the fnow is melted, and while the

water

DISSERTATION, I. 3I

water In many places is yet covered with ice.
The male being about five times fmaller than
the female, cannot nearly bring the toes of his
fore feet to meet over the breaft, a circum-
ftance before noticed in the green water- frog
(vi). He, however, holds her fo faft, that
Ihe can by no means difengage herfelf from
his embraces. The females have often got
out of the veiTels in which I kept them^ and
efcaped to a confiderable diftance, but the
males ftill kept their lituation,

XL II, The eggs, as well as in toads as
frogs, lie at firft in the great facs of the ova-
ria, whence they get firft into the oviducts,
and then into the uterus. In which of thefe
three lituations are they in the female toad
with red eyes, and dorfal tubercles, at the
beginning of her amours ? I have found that
they are indeed in the ovaria, but ready to
pafs into the oviducts. Copulation lafts till
they are difcharged, which happens in ten,
twelve, or fourteen, and fometimes twenty
days, if the feafon be cold. Such is the
ardour of the males, that after the difcharge
is finifhed, and they have quitted the female,
they will return to her again, and embrace
her for feverai hours. This, hov/ever, is
not peculiar to toads, I have often feen it
happen in frogs.

XL I II ,

32 DISSERTATION 1%

XL 1 1 1 . The male, during the whole tim&^
makes a kind of grunting noife> which I
never heard except at the feafon of his a-
mours. This noife becomes louder, when-
ever attempts are made to pull him away, or
when any other toad comes near; which he
moreover obferves with a jealous eye, and
endeavours to drive away by throwing out his
hind legs.

XLiVi If the belly of the female be at^
tentively obferved after feveral days of copu-
lation, it will be {Qtn to move in a very ex-
traordinary manner: it fometimes dilates to-^
wards the breaft, which dilatation paffes gra-
dually downwards j at others the dilatation
begins at the bottom of of the belly, and pro-^
ceeds upwards* During thefe agitations, the
female> now about to bring forth, evidently
fufters confiderable pain, probably on account
of exclulion of the eggs from the ovaria^ and
their paflage through the windings of the
oviducts, and into the large cavity of the ute-^
rus; for the two laft mentioned places will
be found to contain eggs, if the female be
opened during thefe alternate fwellings.

XLv. In frogs the eggs are foon difcharged *
but in toads this is a very tedious procefs*
Two cords, confifting of a vifcid tranfparent
matter, and containing a number of black

globules.

DISSERTATION t. 33

globules, which are the eggs, ifflie from the
vent, and are excluded fo flowly, that the
eye cannot diilinguifh any movement in them 3
but in a few hours they meafure feveral feet,

Thefe cords, confifling of eggs and gluten,
certainly receive their form in the ovidud:s; as
in a prefs; which may be feen upon openino-
the female, as foon as they have advanced a
little way into thofe canals. The time re-
quilite for the difcharge is quite uncertain 5
the longeft I have obferved was iiniihed in
thirty, and th€ fhorteft in nine hours ; it lafts
generally more than twelve. A piece of thefe
cords is reprefented at Fig. 9. Plate II.-Fio-.
10. (hews a fmaller portion magnified.

XL VI. Two entire cords meafured forty-
three Paris feet; the number of eggs amount-
ed to one thoufand two hundred and feven :
hence we cannot be furprized that the female,
after the exclufion of the eggs, fliould have
become fo much fmaller.

XLvii. Since the ardour of the males is fo
great, that they do not abandon the females,
even when they make their efcape (xli), it
was natural to fappofe, that they would alfo
continue their embraces when I removed them
from the ftagnant or flowly running waters,
where they alfemble towards the end of fpring,
in order to propagate the fpecies (xli), to a

Vol. II. D dry

34 DISSERTATION I.

dry and confined place, where I could watch
the manner in which fecundation takes place.
I ihall relate what i obferved during many-
long and tedious infpedtions.

XL VI 11. As foon as the female begins to
difcharge the mucus cords, the male, that
before lay clofe and colleded, fpreads him-
felf, and ftretches his hind legs backwards
towards thofe of the female, ftill holding her
breaft clofe with his fore legs. This change
of pofture enables him to reach the cords with
the extremity of his body, and to bedew them
with femen.

xLix. And this is. not done by a forcible
cmiffion, but by fim.ple con tad; for where -
ever the cord is touched, it appears jufl
moiftened, as if v/ith a pencil dipped in fome
fluid.

L. The male, after having repeated this
operation many times, with various contor-
tions, becomes weary, colleds his body, and
draws his hind legs clofe to his belly. Mean-
while a frelh portion of cord is difcharged, and
then the male refumes his employment, and
afterwards again returns to his repofe. And
thus he goes on, till all the eggs are impreg-
nated.

LI. That the aft of fecundation confifts in
this approximation of the extremity of the

body

DISSERTATION I. 35

body to the eggs, and bedewing them, ap-
pears from the following proofs : Firft, if the
female be killed while llie is difcharging the
eggs, of thofe which lie in the uterus and
ovidudls, not one will be prolific, though
they be kept in proper water; whereas al-
moft all the others that have been moiflened
with the feminal fluid, at their exclufion
from the vent, ^vill produce. Secondly, If
durino; the difchar2:e the irroration fhould be
interrupted, either by means of breeches,
(xiii). or by the near approach of the ob-
ferver, (for then the male through fear will
bi-ing his hind legs and thighs clofe to his
body) the portion of eggs then excluded will
be barren, while the reft will be found to
have been fecundated.

LI I. Thefe laft fads clearly evince, that
in thefe animals like wife fecundation takes
place without the body of the female.

Liii. But may not the bodies, which have
hitherto been called eggs, be tadpoles not yet
unfolded? and if fo, do they exift before im-
pregnation, as in frogs (Chap. I. and II.)?
Thefe problems were yet to be folved, and
required a fhort analyfis of the eggs.

Liv, They are black, and, to the naked
eye, and even when a weak magnifier is ufed,
appear to be globular (Fig. 9, 10. Plate II).

£) 2 ** v/h^n

^6 DISSERTATION I.

when examined with a glafs of greater power>
they feem to be marked with four furrows,
which interfecft each other at right , angles,
nearly like the hufk of a cheftnut half open-
ed, (Fig. II.): though the furrows are not
bare, but covered with a very fine tranfpa-
rent membrane, which pafies very tight round
the reft of the egg. When this is taken
awav, we come to the fkin of the egg^ it is
black, and is lacerated by the fligliteft touch 5
as is alfo the infide, which is almoft fluid, of
a browniili white colour, and apparently ho-
mogeneous; the particles appear globular,
w^hen obferved by the microfcope.

Lv* Such is the form and compofition, as
far as the eye can difcover it, both of the eggs
that have been difcharged and fecundated,
and of thofe that are taken from the uterus
and ovaria; excepting, that the latter are de-
ftitute of the mucous gluten, fmaller,'and not
fo black.

Lvi. Wherefore, if we rely upon the in-
form^ation of the fenfes, we muft conclude,
that there is no effential difference between .
' the impregnated and unimpregnated eggs.

LVii. If w^e obferve the changes produced
in the former, as we have before done in
froo-s, we fhall find that they are immature
fetufcs, and exift before im-pregnation. They '

foon

DISSERTATION I, yj

loon aflume the form of thofe little animals ;
firft becon:iing thicker, then longer, and after-
wards growing thin at one extremity, viz.
the tail, and becoming round at the other;
from which fpring two appendixes, viz. the
gills; and in thefe the cir^culation of the
blood is very confpicuous, as well as at the
edge of the body. At Fig. 14. maybe feen
feveral of thofe little bodies, lofmg the fhape
of an egg, and affuming that of the tadpole ;
they are further advanced at Fig, i ^. Fig. 12.'
ihews fom^e of thefe corpufcles, loiing in-^
deed the form of the egg, but not afluming
that of the tadpole, and fpoiling; this ap-*
pears more at large at Fig. 1 3 : thefe were
never fubjedled to the influence of the fecun-^
dating fluid.

Lviii. While the tadpole is thus evolved,
the thin membrane, of which we fpoke at
Liv. is enlarged in proportion; this mem-
brane is the amnion, and contains a liquor,
in which the fetus is feen to float; it may be
found in the uterus (liv, lv), ^nd therefor^
exifl:s before impregnation,

Lix, Though the blood circulates in the
fetus (lvii). and the heart muft therefore
beat, yet not the fmalleft motion can be
excited, either by punfture, gr any othei;

P 3 inQ4?

38 BISSERTATION 1.

mode of irritation ; it is not till the organs
have acquired fome confiftence, that the ani-
mal" begins to move ; in a few^ days after
this period it burfts the amnion, and fwims
about.

CHAP.

DISSERTATION I. 39

CHAP. IV.

GENERATION OF THE FETID TERRES-*

I
TRIAL TOAD.

LX. 'T^HIS fpecles, which does not much
exceed in lize the green aquatic
frog, (hi)- agrees in fome particulars with
that denominated by Roefel, Bufo terreftris
foetidus, but differs in fo many others, that it
muft be reckoned a fpecies totally diftind:.
They are both nearly of the fame iize, and
v/hen irritated emit an offenfive fmell; they
moreover agree in colour, (the belly being of-
a white, inclining to a green in both^ and
the back to yellow) ; if w^e except a hft of a
golden yellow colour, which, in the fpecies
of Roefel, runs along the fpine, but in mine
does not appear. But the effential difference
conlifts in the abfence of the web that con-
neds the toes of fo many other amphibious
and aquatic animals befides frogs, from the
fpecies defcribed by the German naturalift j
in that of which I am about to treat, it is-
very vifible, and of very great fervice in
fwimming. The fecond difference lie-in the

P4 . fV9^

40 B I S S E K T A T I O N I.

progrefUve motion upon dry ground, thofe of
Roefel advancing without riling from the
ground; mim's in/iar is his phrafe; whereas
mine' leap Uke frogs. Lallly, a difference
of fpecies may be deduced from the differ-
ence of the voice, which, in the former, is
exacftly Hke that of the green tree-frog, and
confifts of a loud fcreaming, but in the latter
is a kind of continued whiflle.

Lxi. The female, in the two other fpe-
eies of terreilrial toad, is five times as big as
the male (xli). But in this fpecies the male
is fcarce one third fmaller than the female,
when £he is about to exclude the eggs; af-
terwards they are nearly of the fame fize.
They alfo agree in colour ; but the upper part
of the body of the female is adorned with
cineritious fpots and lifts, from which arife
fome very beautiful red tubercules.

LXI I. Toads of this fpecies live on dry
ground all the year, except during the feafon
of copulation ; at which tim^e they repair to
the water of pools, ponds, puddles, ditches;
never to rivers, torrents, or quick currents.
. LXiii. They repair to the water when the
fpring is pretty far advanced, in May, or at
the beginning of June. Their amours laft
above a month; not that the male embraces
the female fo much longer than in the other

fpecies.

DISSERTATION I. 4I

fpecles, the contrary is rather true; but, du-
ring all this time, pairs may be found cou-
pled ; fome beginning earlier, and others la-
ter, according as they are infligated by their
internal feelings. The fame thing happens
in the two other fpecies of toad, the aquatic
and tree-frogs, fifhes, and all animals that
have a fixed feafon for their amours.

Lxiv, By comparing paragraph lxiii.
with XL I. the reader will perceive the great
difference of time at which the two other
fpecies of toad, and that which is the fubject
of this chapter, begin to propagate; whence
we may infer, that they are naturally differ-
ent. The former begin early in March, as
foon as the rigour of winter is a little abated;
whereas the latter requires a warm tempera-
ture. If the weather fuddenly changes, the
foetid terreftrial toad abandons the bulinefs
of generation, and retreats to dry ground. I
was eye-witnefs of a fingular fa6t which may
be related on this occaiion. At the end of
May, IJJJ, I perceived upon the furface of '
a large pool great numbers of this fpecies,
fome of w^hich had difchareed their e'^o;s;
others were discharging them, and others were
only juft coupled ; all were in motion, and fo
intent upon their employment, that they fuf-
fered themfelves ^o be taken, without zt^

tempting

42 DISSERTATION I.

tempting to efcape. The males, like the
green aquatic frogs, clafped the brcafi; of the
females very tight with their fore feet, and
made a low grunting noife, not unlike that
of the two other fpecies (xLiii). The iky
was clear, and in the ihade the mercury flood
at 16" {a)^ when an unexpected, rain fell for
two days, and cooling the air, difperfed all
the toads, fo that when I came on the fe-
cond day of the rain, to catch fome for my
experiments, to my furprize 1 could not find
one. 1 foon, however, was aware that they
had quitted the water, to conceal themfelve^
in the crevices of a neighbouring wall, where
they continued till the atmofphere becorning
warmer, invited them again to the pool,

Lxv. It is the opinion of many naturalifts,
that the male toad embraces the female for
forty days; and fome think that this is the
cafe alfo with the frog {i?) . Having obferved
that, in like circumftances, the duration of
copulation is inverfely as the heat of the at-
mofphere, I can eafily believe that this may
be the cafe in cold countries. In temperate
climates, as with us, it is.far otherwife. The
tree-frog embraces the female a few hours

{a) Sixty-eight of Fahrenheit.
(^) Swammerdam Bifal. Naturae,

(xxii),

DISSERTATION I. 43

(xxii), the aquatic about a week (vi); the
two former fpecies of toad longer, on account
of the early commencement of their amours.
It will therefore ealily be believed that, for a
contrary reafon, the embraces of the fpecies
in queftion do not laft long, four or five days
for inftance.

Nothing can be more falacious than the
male. He not only adheres moft tenacioufly
to the female, but does not even quit her for
fome time after the exclufion of the eggs. If
he is feparated by force, he returns to his fi-
tuation immediately, though kept in a nar-
row vefTel, and under the eye of the ob-
ferver.

Lxvi . About the feafon at which thefe ani-
mals meet, I procured a large quantity, and
fet them in veiTels almoft full of water, a male
and female in each velTel. In fome I put only
a female. They were foon coupled, fome
fooner and others later. In two females that
were opened twelve hours after the male had
begun to embrace them, the eggs had not
yet quitted the ovaria ; in one that had been
coupled two days and a half, the fame phas-
nomenon occurred. In another, that was
opened at the end of the third day, fom^e eggs
had entered the ovidud:s, and thofe neareft
the uterus were furrounded by mucus. Be-
fore

44' DISSERTATION I.

fore the conclufion of the fourth day, the eggs
of two other females had all defcended into
the uterus, and were completely furrounded
by gluten. The ovaria now contained only
fmall and immature eggs. Thefe obferva-
tions were made upon females embraced by
the male ; though the folitary ones were kept
for a fortnight, the eggs continued in the
ovaria,

Lxvii. While I was engaged in thefe ex^
periments, a fmgular phenomenon occurred,
which muft not be pajffed over in lilence. Of
two females that were opened on the fourth
day of copulation, I found the eggs of one in
the abdomen, and of the other partly in the
abdomen, and partly in the thorax. This
accident may eafily be explained, The eggs
were without gluten, ^nd therefore could
not have paiied through the long v/iridings of
theoviduds, and had either never been taken
into them, or the ovaria perhaps burft, and
hence they would fall both into the fuperior
an4 inferior cavity. Such a rupture may
eafily be conceived to happen, if we confider
the preflure made by the male againft the re-
gion of the breaft oppofite the ovaria.

Lxviii. I have a:lready laid, that the eggs
about to be excluded having pafled through
the cai^al, - provided by Nature for that pur-

pofe.

BISSERTATION I. 45

pole, were found in the uterus on the fourth
day (lxvi). In the greater part of thofe that
were conlined in my veffels, they began to
make their appearance at the vent on the 5th
day in the form of cords, as in the other fpe-
cies (xLv). Thefe cords continue to be very
llowly expelled till the uterus is empty, which
always happens before the feventh day,
■Meanwhile the male brought the extremity
of his body towards them, from which iffued
a fmall jet of liquor; this was the femen, as
evidently appeared from thofe portions of
cord that were fprinkled with it bringing forth
tadpoles, whereas the others fpoil and turn
putrid. In like manner the whole length of
the cords produced nothing when the male
was clothed with breeches (xiii), or parted
from the female as foon as the eggs beo-an to
be excluded.

-I.XIX. As the eggs that were not moiftened
v/ith the femanal fluid after they were dif-
charged, were unproductive (lxvi 11), I may
confidently infer, that fecundation takes place
without the body of the female. I have
moreover frequently taken pieces of cord out
of the uterus, and placed them in water, but

never did I fee one egg productive ; this ob-
fervation is likewife applicable to the eggs

that were defcending through the long wind-

46 DiSSfettTAttON 1.

ings of the ovidu<!ls. Hence might be in--
ferred the phyfical impoflibility of the eggs
which w^re ihed in the cavities of the thorax
and abdomen being prohfic (lxvii), as ex-
periment decifively proved*

Lxx» The cords, upon examination, ap-
pear to confift of an almofh innumerable fe^
ries of eggs, each at a fmall diftance from the
other: they are connedled by that gluten^
which always enclofes the fetufes of the frog
and toad, and which is prepared in the cavity
of the ovidu6ls, for in them the fetufes, be-
fore naked, are inverted with it. The great
refemblance between the phsenomena exhibited
by the tadpoles that I am about to defcribe,
and by thofe already defcribed (Chap. Ill),
renders a reference to figures unneceflary.

I was curious to know, whetlier the glu-
ten is neceffary to the growth of the egg, I
therefore removed it entirely from fome, and
from others only in part, without injuring the
amnion, which in this as well as in other
fpecies of frogs and toads, is very confpicu-
ous. Thofe which were quite ftripped of
their gluten, never brought forth young, but
the others, to which a portion was ftill left
adhering, were prolific. When the amnion
began to fpoil, it was a certain fign, that the
egg, though yet found, would fpoiL

LXXI, Ib

DtSSERTATION I. 47

Lxxi. In this fpeciesalfo, the little bodies,
which we have hitherto called eggs, are tad-^
poles in miniature, as the following proofs
may ferve to ihew. They are not broken like
other eggs, to allow the inclcfed animal to
pafs out, while they themfelves become an
empty and ufelefs lliell^ they undergo no
other change than an increafe of bulk, be-
coming (lender at one extremity, at which the
tadpole foon appears, and round at the other,
which the eyes, the mouth and gills foon
iliew to be the head; at length life appears
in thefe fetufes, they break through the am-
nion and fwim about the water; juft as the
fetufes of the other frogs and toads, which
like wife have at firft the fhape of eggs. The
advanced feafon caufes the tadpoles of this
fpecies to exhibit their different phafes in
lefs than three days, whereas others beinp-
brought forth at an earlier period, require a
longer fpace of time.

LXXI I. During the evolution, I analyfed
thefe corpufcles with the utmoft care, and
compared them both internally and externally
with others in the uterus and ovidudis, but
could perceive no difference except in fize.
From this identity then it may be concluded,
that as thefe corpufcles are real tadpoles when
they are without the body of the female, they

are

48 DISSERTATION ll

are Co alfo within it, and by confequence, that
the fetus exifls in the female before the con-
currence of the male.

-, Lxxiii. This is alfo true of the amnion,
for I have found that membrane furrounding
the fetus, when in the uterus ; it is then, in-
deed, in contad: with the fetus, and does not
contain any liquid; when they are excluded,
it is at fome diftance, and full of its proper
fluid. In like manner there is reafon to be-
lieve, that the umbilical cord exifts before
fecundation. This organ is indeed not vili-
ble, when the tadpole floats in the liquor of
the amnion, yet it probably exifls, fince it is
attached by ono. end to the lower part of the
head of the animal, and by the other to the
amnion, from which it afterwards feparates,
and adheres a little while longer to the tad-
pole ; it then decays by little and little, and
is at laft quite obliterated.

Lxxiv. I faid, that in order to rear thefe
animals, I immediately put them into water,
imitating in this the example of the female.
I added, that except for the tree-frog, well
water would fuffice, that fpecies requiring it
to be taken from certain ponds or ditches
(xxxix). To thefe precautions, I muft fub-
join two others, for the fake of thofe who
may be defirous of repeating my experiments.

Firll,

DISSERTATION l", 49

Firft, The veflels muft not be kept in too
warm a place, cold being lefs hurtful in thefe
experiments than heat: the two firfl fpecies
are produced before the clofe of winter, and
the water of the veffels in which I kept them
has been frozen to a confiderable depth,
without doing any hurt to the tadpoles. I
twice increafed the cold to fuch a degree,
that almoft all the water was frozen, but the
tadpoles never fufFered, except when the mu-
cus itfelf, in which they were enveloped, was
frozen; which never happens, but in a de-
gree of cold far exceeding the point of con-
gelation. On the contrary, whenever I left
them feveral hours expofed to the fun, when
the thermometer flood at 35% the greater part
was fure to perifh.

The next precaution, Hot lefs important
than the preceding, confifts in often chang-
ing the wat^ of the veflels ; if this be neg-
ledled, evolution will not begin, or if begun
will flop ; this happens in confequence of the
gluten becoming putrid, from which a pe-
netrating mlafma infinuates itfelf into the ten-
der and delicate fetus, and deflroys it either
before it fhews any figns of life, or after it has
given tokens of animation*

In order to obferve exadlly the amours of
confined frogs and toads, it is neceffary to

Vol. II. ^ E place

^a DISSERTATION I.

place fome thing to obfI;ru6l the view of thefe
falacious animals, between the vefTel and the
obferver, other wife they are difturbed at the
fight of a perfon flanding over them, and
either do not begin to celebrate their nup-
tials, or leave them half-finiilied.

Nice and faftidious perfons may perhaps be
difgufted at the frequent mention of an ani-
mal fo loathfome as the toad. They would
doubtlefs have been better pleafed with re-
marks on fuch creatures as are more familiar,
and may be handled without abhorrence. But
whoever purpofes to explore Nature, con-
ceives not difguft or predilection for any of
herproduftions, but examines all indifferently,
well knowing, that the ideas of what is dif-
agreeable^ naufeoiiSy &c. are not in Nature but
the imagination; for every creature, how
vile and horrible foever it may appear, has
its proper beauty and grandeur, and is the
proper objed: of admiration, fince it is the
work of the fupreme Architeft. This did
not efcape the fage Petrarch, who fmgs

Tutte le cofe di che '1 Mondo e adorno
Ufcir buone di man del Maftro Eterno.

Lxxv, I will clofe the chapter, by no-
ticing a fa(ft mentioned by the illuftrious
Bonnet in his Corps organises, and conned:ed
with the prefent fubjed:. He tells us, that

he

DISSERTATION I. gt

he knew a pool, which, after remaining dry,
for fome time, was ftored with the fame kind
of fifli that it contained before, nor could he
difcover how they came into it. Inftead of
having recourfe to fifhes accidentally dropped
by cranes for the explanation of the phasno-
menon, he conjectures, that the fupplycame
from fecundated eggs that had lain in the mud
without being fpoiled. The inftance of a
fpecies of tufted polype, difcovered by the im-
mortal Trembley, of which the eggs may be
hatched by putting them into water, after
they have been kept four months in the dry,
affords a remarkable foundation for his con-
jed:ure ; which he further confirms by the fa-
mous worms of ricketty corn ; thefe, it is
well known, after having been kept dry for
many years, will move again as well as at firft,
if they are barely wetted. Defirous, how-
ever, on this as well as on all other occafions,
of afcertaining the truth, the philofopher of
Geneva wifhed that his conjedlure m^ight be
fubjedied to the tell of experiment, and that
it might be tried, whether the eggs of fifhes
can be hatched after having been kept fome
time in the dry.

As' foon as I had read the work, I made
the experiment, but without fuccefs. Of
the eggs of three fpecies, which I kept in the

E z dry

52 DISSERTATION 1.

dry for a month, hot one brought forth ydiing;
indeed this appeared to be impoffible, for
tnoft of the eggs were deformed and fpoiled
by deficcation. Several years afterwards, be-
ing engaged in experiments relative to the ge-
neration of toads and frogs, I put tadpoles
recently excluded to the fame trial,, and with
the fame ill fuccefs. Hence it appears, that
in order to explain the phaenomenon related
by Mr. Bonnet, we cannot have recourfe to
the fuppofition, that eggs may be long kept
in the dry. And I am Hill more inclined to
this opinion, from having obferved, that the
eggs of filhes and tadpoles, newly laid in a
iliallow place, perifli irretrievably if they con-
tinue in the dry for a few days, notwithftand-
ing they are afterv/ards put in water. I fay
for a few days, for tadpoles do not die if they
continue but a little while out of water. I
put fome tadpoles juft excluded into a dry
glafs^ for two or three days the evolution
went on, they began to affume their true fhape^
and even to fliew figns of life, but thefe ap-
pearances diminiihed gradually, and at lafh
they fhrivelled up and became disfigured amid
the mucus, which was itfelf turned into a
kind of hard glue.

Lxxvi. But how then are we to explain
the appearance of filhes where there were

none

I^I3SERTAT^0N J. 53

none once, and where we know that frefh
ones have not been brought ? The purport of
this differtation does not, as is evident, lead
me to the folution of this phasnomenon, which
was only mentioned incidentally. And if I
was obliged to treat of it, it would rather be
to fuggeft doubts concerning its reality, than
account for it. We know not how any fifhes
have got into places tha^t were once dry, and
are qow covered with water, but is it there-
fqre certain that they did not get there ? Atq
we fure that nobody put them there ? Is it
clear that they themfelves have not found
fpme fubterraneous way, or unperceived rill ?
IMuft we not of neceffity draw fome fuch con»
clufion, fmce it is certain, on one hand^ th^
the dried eggs of fifhes are fteril, and on tli;^
other, that fifhes corne only froni eggs ,

£ 1 CHAP,

54 DISSERTATION I»

CHAP, V,

tjENERATION OF THE WATER-NEWT, DH
SALAMANDER,

LXXVIL ]\/| Y obfervatlons were made
"^ upon two fpecies of newt.
One has the lower part of the body tinged
with a very beautiful orange colour, inter-?
fperfed with black fpots of an irregular fhape ^
the fides and back have a ferruginous ground
with grey ftreaks > the length of this fpecies
is four inches and upwards, and the thicknefs
about fix lines. The other fpecies, befides
being fhorter and lefs bulky in proportion, is
difi:ingiii(hed from the former by a lifl: pf a
golden yellow, which bounds the ridge of
the tail, and in females paifes upwards along
the fpine, and reaches as far as the head, In
both thefe fpecies the males differ from the
females, not indeed in the external parts of
generation, which are alike in each fex, but
in being provided with a dentated, membra-
nous prominence, running longitudinally
along the middle of the back^ as alfo in a
double filver-coloured band^ which adorns

the

DISSERTATION I. ^^

the tail of the male, but is not perceptible in.
that of the female. Thefe two forts of newts
arc the fame which, in refearches of another
nature, were the fubjedts of thofe beautiful
experiments on the reprodud:ion of the limbs,
the circulation of the blood, and other inte-
refling topics, difcufled in my other Vv^orks al-
ready publifhed.

Lxxviii. During fpring and fummer thefe
little quadrupeds live in fcagnant, never in
running waters ; at the approach of winter
they conceal themfelves under ground, with-
in the clefts of ftones, and even in vaults ;
many of them, however, abide in the water
during the whole winter, and more efpeci-
ally in fuch as arifes from fubterraneous
fprings, and preferves a fenfible degree of
warmth in the keeneft colds. Hence it ap-
pears, that our newts, though in general na-
tives of water, and therefore denominated
aquatic by me, are, however, capable of living,
and in reality do live upon dry ground; and
for this reafon they may alfo be juftly termed
amphibious.

Lxxix. The comparative ftate of the fea-
fon at which they difappear from the waters
(either defcending to the bottom, or elfe
tranfporting themfelves to dry ground,
J. XXVI 1 1) in autumn, and of that at which

E 4 they

5^ t) I S 5 E R T A T I O » i;

they re-appear on the approach of fpring, is
wof thy of notice. Before the middle of Oc-
tober, while in our cHmate the thermometer
in the fhade has fcarce fallen fo low as tem-
perate, they all or almoll all retire out of fight,
and are loft^ whereas, on the other hand,
they begin to make their appearance, either
by riling to the furface of the water, or fwim-
ming in it towards the middle of February or
thereabouts, although at this time it continues
to freeze almofl: always during the night, and
in the day-time the thermometer in the fhade
is feveral degrees below temperate. Now
whence arifes this early difpofition in newts
to quit their retreats, while the winter is not
yet over, whereas in autumn they go in queft
and take poffeffion of them, notwithftanding
the feafon long continues mild ? Does it fpring
from the ftimulus of hunger produced by
their long fail during the winter months ?
Of. may it more jujftly be imputed to another
principle not lefs adive than hunger, viz.
that by which the individuals of different
fexes are determined to feek each other for
the purpofe of propagating the fpecies ? It is
at leaft certain, that in fpite of the coldnefs
of the feafoji, which, however, prevents them
from fhewing fuch vivacity, fuch fire and
alertnefs, as they afterwards difplay, the males

begiii

DISSERTATION !• 57

begin to chafe the females, to furround and
to carefs them after their manner, a circum-
ftance which is never obferved except at the
time of their amours.

Lxxx. Thefe appearances in February are,
however, only preludes to their future nup-
tials. Thefe are properly celebrated in March,
and till about the middle of April ; this how-
ever depends, as we have already feen in frogs
and toads, on the greater or lefs warmth of
the feafon, which accelerates or retards their
amorous encounters. Thefe encounters are
condud:ed in this manner: the male purfues
the female, which at firft makes a £hew of
flying, but foon flops of her own accord. He
then approaches her in fuch a manner, that
the lower part of his head comes in contacft
with the upper part of the head of the female ;
and this is done while the animals are in fuch
a pofture, that their bodies form an angle,
of which the point is made by the union of
the two heads. Sometimes, however, the
pofition varies ; fome males, inftead of pla-
cing their head on that of the female, only
join muzzle to muzzle j the bodies of the
male and female are always near together, fo
that the angle made by the two heads or muz-
zles, is very acute. Then the male ered:s
that dentated membranous prominence which

l|es

5^ DISSERTATION ?.

lies on his back (lxxvii), agitates it in an
odd manner, and moves it from left to right,
nearly as a mettlefome fcallion waves his mane ;
he alfo moves his tail brifkly, bends it in a
tortuous manner, and as he waves it about,
ftrikes very gently the fides of the female,
which continues without motion. Some-
times the male, in order to preferve his po-
fition, and at the fame time to lafli the female
with his tail, grafps with the toes of his fore-
feet the grafs at the bottom of the ditch, or
fmall twigs, or whatever elfe will ferve for
a fuppcrt, remaining always immerfed in wa-
ter along with his companion; and while he
thus gently lafhes the female v/ith his tail, he
emits from the aperture of the anus, now un--
ufually tumid and dilated, a copious jet of fe-
men, which mixes with the water, and thus
diluted, arrives at the vent of the female,
which likewife, on this occafion, appears
more enlareed as v/ell as wider than ufual. In
this important operation then, the anus of the
male is never in ccntadt with that of the fe-
male, which alfo always maintains a greater
or fmaller diftance, and never feews any part
at all charadteriftic of her fex. After the
male has ejected this jet of femen, he refts
for a while, on feme occafions quitting the
female; he then returns to his em.ployment,

and

BISSERTATION I» 59

and repeats the contortions of the tail, and
the emiffion of femen. I have feen thefe al-
ternations continue more than an hour; and
when they are engaged in this employment,
they may be approached and taken with the
hand, almoft without being aware of what
happens to them. And fometimes the male,
from his agitation and contortions between
the fingers, throws out a fmall portion of fe-
men, which is of a: very white colour, and in
confiftence refembles thick milk.

Lxxxi. I firft obferved thefe curious fads
in places where the newts naturally affemble
and fport together, viz. in ponds^ ditches,
puddles, &c. afterv/ards I obferved over a g-ain
the fame things at home in veiTels full of wa-
ter, m.ore cpmmodiouily and with equal fuc-
cefs, exadlly in the fame manner as I had ob-
ferved the generation of frogs and toads. I
found that this fmgular mode of impregnation
. takes place in both the fpecies of newt which
I have defcribed (lxxviii). Upon the whole
it appears then, that copulation is not r^ecef-
fary to the fecundation of thefe animals, and
I can ailert with confidence, that among the
' many thoufands which I have obferved at the
time of their amours, I have never feen a fia-
gle pair in conjuncTtion, not only for the

purpofe

6q dissertation I.'

purpofe of generation, but on any other
occafion.

Being well affUred, that with refpeifl to
exceptions from certain rules fuppofed to be
general, diffidence and caution can never be
carried too far, I was very deiirous of remor
vjng all fufpicion. I have been feyeral times
^. fped:ator of the copulation of wall-lizards^
which happens in April and May, and may
ho, faid to laft a fingle inftant. ' In the cleareft
days, and in places moft expofed to the fun,
the male runs after the female, and when he
has overtaken her, he twines himfelf about
her, and unites his genitals tq her's, but this
union may be termed momentaneous, after
which the two animals parf. Do newts alfq,
which on account of fome refemblance, are
likewife called water-lizards, during their
amours as defqribed aboye (lxxx), do they
alfo, I fay, copulate for a fmgle inftant ? Al-
though I kept my eyes fixed on them, fo that
the moft trifling aftion or fmaHeft motion
CQuIc} not efcape me, I am quite certain of
having never ktn them in copulation for a
fingle moment throughotU the whole period
pf their amours. I may even aiTert, that the
genitals of the male were always at the c^if-
lance of feveral line^ from thofe of the fe-
male I and I have been ftill more ^nd more

con^

DISSERTATION I. 6t

convinced, that no copulation of any fort
takes place in this kind of animals, but that
fecundation is effeded by that portion of
femen which the male darts into the water,
and which afterwards is received into the
body of the female, at the aperture of the
anus.

Lxxxii. I made thefe obfervations in 1766
and 1767, and gave fome intimation of them
in my Frofpedlus concerning animal re-produc^
tions, publifhed in 1768: my expreffions are
the following: *^ Naturalifts are not certain
whether newts copulate like the generality of
animals, or in the manner of frogs and toads.
As fuch an enquiry is of importance to the
hiftory of generation, I have paid great atten-
tion to it, and in my work fhall relate all
that I have obferved {a)J[

I was perfuaded that thefe obfervations
were new, for in truth I was not apprized
that any perfon had publifhed any thing upon
the fubjed. And I iliould ftill have re-
mained under this perfuafion, if I had not
chanced to read in Bomare's DzBionary of
Natural IiiJlory\ the article Aquatic Ne'Wty
in the volume printed in 1775, that is to fay,
feven years after the publication of my Pro-

W Page 77.

fpeclus.

'Si. tj i s s E R T A t I 0 Jr ti

fpeftus, in which I found that Mr. D^mours
had turned his attention to the fame point:
I was not able to afcertain whether his ob^
fervations are prior or pofterior to my own,
for want of knowing whether they are to be
found in a "feparate pubhcation, or were
limply communicated by the author to Bo-
mare. However it may be, I acknowledge
with the moft unafFed:ed ingenuoufnefs^ that
the painful feelings, which ufually arife on
perceiving that another, without our know^
ledge, has begun to reap in our own field,
have been amply compenfated by the pleafure
of finding that the obfervations of the French
Naturalift perfedly agree with mine upon the
whole, a ftrong prefumption that the obfer-
vers have been exad:. The fum of his ob-
fervations is, that after various gallantries on
the part of the male, fuch as flopping the fe-
male, bending his body in the form of an
arch in the water, and Handing upright with
his creil or prominence eredled, he opens his
anus, forcibly compreffes the region of the
tefticles, laflies his companion with his tail,
and nowfqueezing his tefticles with his utmoft
force, darts forth the feminal liquor, without
however being in contad: with the female*
The liquor fpreads along her fides, after
,ilightly clouding the water: Then the male

drops

DISSERTATION I. 63

drops down as it were afleep, but foon awakes,
and reaffumes his former gallantries, which
are fucceeded by a frefh emiffion of femen, af-
ter which the two animals feparate [a).

Thefe obfervations, as far as they prove
that no copulation takes place between newts,
are conlirmations of mine, whatever opinion
ivs to be entertained concerning any flio-ht dif-
ference in the accounts of the amorous gefti-
culations, as well as concerning the few emif-
fions of femen obferved by him, and the nu-
merous ones remarked by me (lxxx) : for
with refped: to the former, they are circiim-
ftances totally foreign to the main-obiecl of
attention, and as to the more or lefs frequent
emiilions of femen, thefe it is evident mip-ht
depend on the difference of temperament,
age, and vigour of the animals.

Lxxxiii. In the Lxxxift paragraph I have
fuppofed that impregnation was effeCled by
thofe jets of femen which the male emits in
the vicinity of the fem.ale. Let me nov/ ad-
duce the proof of this fuppofition ; but that
it miay be better underftood, it will be expe-
dient to prem.ife fomething concerning the
ovaria, oviduds, and ova of thefe anim.als„
When the abdomen oi a female newt is laid

{a) Page 3S, 39.

open

^4 DISSERTATION tl

Open at any feafon of the year, the two ovark
prefent themfelves, containing a multitude of
little eggs of a yellowiih white colour, fmal-
ler than huiked millet, and not floating loofe
in the cavity of the ovaria, but adhering to
their fides. The little ova, at the approach
of fpring, increafe infenfibly in fize, and when
they are arrived at maturity, (which happens
at the time of their amours) they defcend into
the ovidudls, which confift of two white
tubes, which extend from the origin of the
fore-feet to the root of the tail, and include
the fpine between them^ Both are wrinkled
and full ojT curvatures and flexions, when they
are freed from thefe, and ftretehed in a right
line, they exceed about four times the whole
length of the animal,

Lxxxiv. During the feafon of amours, the
ovidudls always contain a greater or fmaller
quantity of eggs, placed in rows, and gene-
rally more numerous in that part of the dud:
which lies nearefl: the anus. And now it is,
that on flight prefliire on the belly, or even
from the contortions of the animal, when
they are held between the fingers, the eggs
commonly come out from the cloaca, jufl: as
y^^e have before obferved, that the femen of
the male is emitted under like circumflances
(lxx^). The ova, when they quit the ovaria

and

DISSERTATION T. 65

and enter the ovidu6ts, become far larger,
and they now are inverted with a vifcid glu-
ten, nearly as in frogs and toads, e:xcept that
the gluten which furrounds the eggs in the
two latter kinds of animals is more abundant
and more vifcid. When the male has ejected
the femen, and when from its vicinity to the
female, it has infinuated itfelf into her anus,
that portion of eggs is fecundated, which is
neareft the vent, and about to be excluded,
iand the remainder which lies in the higher
part of the ovidu6l, continues at that time
unimpregnated, as I found from the follow-
ing experiment. When the males began to
purfue the fem.ales with eagernefs, I put the
latter by themfelves in vefTels full of water.
They, notwithftanding, difcharged their ova,
but they remained barren. I allov/ed the
males to approach, and they darted their fe-
men as uf aal ; I then again feparated the fe-
males, when 1 found that the firft eggs they
difcharged (amounting to fix, feven, or there-
abouts) furnifhed me after fome interval with
living newts. But this was not the cafe with
others lying higher up in the ovidudts, which
were brought forth afterwards.

After the amorous encounters were over,
I opened a female, and taking the eggs out
of the dudls, I put themjnto water, with

Vol. 11. F the

66 DISSERTATION I.

the precaution, however, of placing thofe
which lay in the vicinity of the anus in a fe-
parate vdTel. Thefe produced young, while
the reft all failed. To thefe proofs, which
in my opinion are deciiive, let me add another^
The fpecies of newt, with the golden lift
upon its back (lxxvii), inftead of bringing
forth the ova feparate like the other fpecies
produces little cords, fometimes of the length
of two inches, confifting of feveral dozens
of eggs. After the male had careiTed one of
thefe females, I opened the abdomen, and
took the eggs out of the duds, which were
united together by means of the glue, and
formed two cords joining at an angle near the
cloaca. I placed thefe cords in water, and
marked the end which would have appeared
firft with threads. And the eggs at and near
this end produced young, while the others
came to nothing.

Lxxxv. Though I have proved that thefe
eggs are not fecundated, yet it does not fol-.
low they do not become fo in the fequel. In
proportion as thofe which lie neareft the anus
are expelled, the more remote defcend and.
take the place of the former, and are impreg-
nated by new emiflions of femen. The fame
thing happens to the moft diftant, fo that all,
that arrive at maturity, pafs out of the ovaria,

and

DISSERTATION I. 67

and enter the cavity of the oviduds, are fooner
or later fecundated. I had an irrefragable
proof of this, by attending to fucceffive dif-
chargcs of ova, which all produced young
alike. From what has been already advanced,
it is very obvious to infer, that the males do
not foon abandon the females. From obfer-
Vation I have learned, that their amours laft
fometimes twenty, fometimes thirty days, and
fometimes ftill longer, viz. until the females
have difcharged all their mature egf>s. For
as long as any remain in the ovidudts, the
males never ceafe their careiTes, and alternate
emiffions of femen> and intervals of reft
(lxxx). I faid 2ihowQ all their maim'e eggs y
fince after the amours of the newts are ended,
there remain within the ovaria others of very
fmall fize, and in very great abundance.

LXXX VI. Bomare, in the article already
quoted (lxxxii), afferts that aquatic newts
dilburthen themfelves of the load of their eggs,
by laying hold of them with their mouths
and feet, and thus promoting the difcharge
from the anus, but that as they are expelled
they are glued under the tail. The French
writer will I hope pardon me, if I venture to
affert that no fable can be more extravagant
than this account. If inftead of being a co-
pyift by profeffion, as he appears to be from

' F2 an

6S DISSERTATION I«

all his publications, he had taken the trouble,
to obferve Nature, and in confequence of
this had enquired into the manners of newts,
he would have feen upona thoufand occaiions,
that the eggs are difcharged and feparated
from the anus without the, concurrence of
the mouth or feet, and that thefe animals
never fhew the leaft difpofition to employ
either the one or the other. He would have
befides felt with his hands, that far from fol-
lowing the pradice of cray-fifh, which after
having brought forth their ova, keep them
attached to the inferior furface of the tail,
that thefe animals expel them in fuch a man-^
ner, that they all fall to the bottom of the
water. Of the infinite number of newts
which I have kept in different years, and for
different purpofes, in veffels full of water, I
have never found one individual that carried
a iingle egg adhering to the tail, but when
the water in the velTels was changed, they
were always feen in an heap at the bottom.
I remarked the fame thing in thofe that were
wandering at pleafure about the water in the

open plains.

And fmce lam fpeaking of the article AT^'z^;/,
compiled by Bomare, let me point out ano-
ther of the various errors which it contains.
He alferts, that the cry of the water-newt

very

DISSERTATION I. 6g

very nearly refembles that of the frog (page
35), whereas it is fufficient to be very Ihghtly
acquainted v^ith thefe animals, in order to
be allured that they are quite mute. It is
only when they rife to the furface of the wa-
ter, to expel the old air from their lungs and
to inhale frefh, that the obferver hears a fort
of very low whiille, fcarce perceptible at the
diftance of four paces. But in an author, to
whofe lot fuch inaccuracy and want of dif-
cernment have, as- numerous other fabulous
tales, with which his Didionary abounds,
may ferve to fliew, fach errors are lefs un-^
pardonable.

Lxxxvii. But let us proceed to the hatch-
ing, or rather the evolution of newts, another
part of their hiftory not lefs curious and in-
terefting than the preceding. Let us then
attend to. what happens to the eggs after they
have been brought forth. Thefe, when put
into water, link to the bottom; if the wea-^
therbewarm, a quantity of air-bubbles foon
appears upon the gluten which includes them ;
thefe at firft are very fmall, but become af-r
terwards larger, and at laft fo large, that the
eggs become lighter than v/ater, and arife to
the furface, bringing with them the collec-
.tion of bubbles Itill adhering to the gluten:
th^ bubbles then burft and difappear, ^nd

F ? now

/

O DISSERTATION I.

now the ova fall again to the bottom, and
rife no more, being kept down by the gluten,
which faftens them to the fpot on which they
reft. If we continue to watch them atten^
tively, we perceive that their fhape begins to
change. When firft brought forth, and for
one or two days afterwards, they referable an
elongated fpherule ; the fpherule now begins
to appear flightly curved, reprefenting in mi-
niature a kidney, or the tefticle of a cock.
The curvature encreafes, and the bulk in the
fame proportion, but with this additional
circumftance, that one end of the ovum be-
comes thicker, and the other thinner. In
the mean timej it acquires twice its original
fize. And now it appears not to grow in bulk,
but only in length; and this becomes every
day more apparent to the furprize of the ob-
ferver? But his greateft furprize arifes from
feeing the egg thus elongated, agitate itfelf
at intervals with great brifknefs, and then
continue, quiet : and as this happens without
any external exciting caufe, the idea of ani-
mality neceffarily arifes in the mind, and we
incline to believe that the fuppofed egg is a
real newt, only in difguife, juft as I have
difcovered that the fuppofed eggs of frogs and
toads are not eggs, but tadpoles in difguife.
This idea continues tp be more and more con-
firmed

DISSERTATION I. ^\

firmed in the fequel, from obferving by a glafi^
the felf-moving egg affum.e the features of a
fmall newt, the tail appearing perfectly for-
pied, the vertebrse beginning to iliew them-
felves as well as the little gills within which
the blood circulates, and likewife two lateral
protuberances, which the obferver fufpecfls to
be the rudiments of the arms, and the vef-
tiges of the head and muzzle, and laftly the
outlines of the eyes lying by the fide of the
head, under the appearance of two incon-
fiderable tumours. Continuing to employ
the microfcope, we perceive that the little
newt is not now circumfcribed by the gluten,
but by a tranfparent circlet more interna],
which is nothing elfe than the amnion full of
liquor, within which the little animal has it§
reiicjence; its colour is alfo remarkable, the
inferior part of the body is white, while the
upper part is yellowilh, and interfperfed v/ith
feveral blackifh ftreaks. N'* L Fig. i6. PI.
III. reprefents a newt's egg in its natural
ftate, furrounded by gluten: N'll, III, IV,
V. fhew the fam0 egg ftripped of its gluten^,
and infenfxbly becoming curved and elongated*
N"* VI, VII. reprefent the body Rippofed to
fee an egg, but which from its progreiTivc
elongation and evolution, has afTumed the
real appearancpe of a fmall newt, fomewhat

F 4 magnified.

*]Z DISSERTATION I*

magnified. D. fig. 17. fhews the fiime cir-
cumfcribed by the amnion, which is repre-
fented by the fmaller circle, but the whole
was obierved by a microfcope of greater mag-
nifying power.

Lxxxviii. As long as newts remain in the
amnion, they are never feen extended at full
length, but always incurvated in fuch a man-
ner, that the tail approaches to the head, as
may be obferved in fig. 16. N'' VI, VII. and
at D. fig. 17. It cannot indeed be otherwife ;
fmce the diameter of the amnion is much
fliorter than the young newt, they mull of
neceflity be bent. Whilft they are confined
in this prifon, they change their fituation
from time to time, and always with incredi-
ble quicknefs, on a fudden tranfporting the
head where the tail lay and reciprocally ; and
this happens not only when they are ftruck
by any fubftance, but even when they are left
undifturbed.- Mean while they increafe in
fize from the food they take within the am-
nion, but when afterwards that membrane
can no longer contain them, they burft it by
repeated efforts, and entirely quit their en-
velope, and begin to fwim about the water,
by the help of quick vibrations of the tail. I
have feveral times beheld this exit with plea-
fure^ it recalled to my memory the exit of

but-

DISSERTATION I. 73

butterflies, when they lay afide the mafic of
the chry falls. In fig. 17, 18, 19. are fcen
three newts juft out of the envelope; two
with their backs prefented, fig. 17 and 19,
and one laterally, fig. 18. In the fame figure
we have two others, fome time emancioated
from their confinement, and fv/imming about
the water. Thefe two young newts, as well
as the two others that are coming out of their
envelopes, fig. 17 and 18. iliew the promi-
nent rudiments of their fore legs, under the
appearance of two little ftumps. Two of
thefe are marked C. C. fig. 17. So the letter
A. in the fame figure, reprefents one of the
above-mentioned envelopes. Upon examin-
ing fome, which were no longer receptacles
for young newts, they appeared to be exter-
nally compofed of a refiduum of gluten, which,
at its internal furface, had become callous,
of the extremely fine and tranfparent mem-
brane of the amnion, and of a little of the li-
quor of that membrane, which was alfo tranf-
parent and flightly vifcid.

Lxxxix. My next objed: of enquiry was,
the time requifite for thefe animals to pafs
from the illufive form of ovum, to the real
one of newt ; this I have found to amount to
the fpace of feven days, more or lefs. They
require three or four more before they come

to

74 DISSERTATION I.

to burft the amnion and gluten, and to float
at liberty in the water.

In general, to hatch thefe animals is more
difficult, than to hatch the tadpoles of frogs
and toads. Though the fetufes of the newt
(falfely fuppofed to be eggs) are put into pure
water as foon as they are brought forth, and.
this water £hould have been taken from the
very fpot in which they were depofited by
the females, yet few come to perfed:ion,
unlefs we are careful to change the water
very often; and even with this precaution,
there is always, in like circumftances, a
fmaller number of young newts than tadpoles
evolved.

xc. This difficulty does not Qccur in their
further evolution and growth. Any kind of
water, either pit, rain, river, or lake water>
will anfwer this purpofe perfectly well, pro-
vided it is pure. If there ihould happen to
be any plant, fuch, for inftance, as the marfh
lentil, in the water which contains the young
newts, they will furround and nibble it with
their little mouths, feleding thofe parts which
are bell: adapted to their conftitution. Du-
ring the progrefs of evolution, the arms are
unfolded more rapidly than other parts
(lxxxviii), they become pointed, and are
bent back towards the pofterior part of the

body.

DISSERTATION I. y^

body, as may be ken in the two young newts
at the bottom of fig. 19. but better in fig. 20,
in which the animal appears magnified. The
two cones marked CD. are the two arms;
above which, and nearer the head, the gills
are fc&n branched, as alfo two other finaller
bundles of gills, E. F. near the eyes; thefe
fmaller gills appear later than the large ones.
The young newts being ftill kept in water,
about a week after their exit from the egg,
three other very fmall cones, not far diftant
from each other, flioot from the ends of the
two former; thefe cones are foon perceived
to be fingers belonging to the little hands.
The animals now begin to employ thefe fin-
gers, hands, and arms. In like manner as the
anterior limbs make their firft appearance in
the fhape of two cones, fo alio do the pofte-
rior, which commonly are firft perceived, fif-
teen and fometimes twenty days after the
animals have quitted their envelope. Nature
like wife cbferves the fame progrefs in pro-
ducing the toes as the fingers ; and now the
newt is able to walk, either along the bottom
of the water, or on dry ground. It is well
known, that the tadpoles, both of frogs and
toads, lofe their gills a few days after their
birth. Young xiewts, on the contrary, re-
tain

y6 DISSERTATION I.

tnn them long, and I have even obferved
them in Auguft. '

xci. There ftill remains an important en-
quiry relative to thefe animals, the fame which
has been already made concerning frogs and
toads. At what period may thofe roundifh
bodies, commonly called the eggs of newts,
be properly termed true fetufes ? I3 it when
|;hey are upon the point of being expelled from
the body of the female, and confequently have
been already bathed by the femen ? or ftill
fooner, v/hen they lie in the upper part of the
joviduds, where' we are certain that the fe-
men could not arrive ? 1 flatter myfelf, that
I have the moft dired: proofs that thefe little
bodies are real animals, even vv^hen they are
at the top of the ovidudls ; although when
taken out of the body of the female, they are
not developed, but come to nothing, for want
of the neceflary condition of being fecundated
by means of femen, Thefe proofs are de-
duced from the identity of the impregnated
iMid unimpregnated corpufcles: and I hope
the reader will be fully convinced pf this
identity, vv^hen I aiTure him, that I have fub-
jeded each to the fame minute and rigorous
analyfis,, that was employed upon the fetufes
of frogs and toads, and which is particularly
defcribed in the Lxxviiith paragraph; nor

' could

DISSERTATION I* 77

Gould I difcover the finalleft difference, either
ill the internal or external parts, between the
Gorpufcles bedewed with femen, which were
evolved and became newts, and others not
touched by that liquor which were fpoiled* I
therefore conclude, that in thefe animals alfo,
the fetufes exift in the females before they
are impregnated by the male.

xcii. I have fpoken of the two forts of
newts defcribed in paragraph lxxvii, and
which have been hitherto the objedls of my
enquiries, as if there had been only one, hav-
ing obtained from both the fame refults in
every thing that refpedls generation. I will
moreover add, that thefe refults have been
the fame in another fpecies of this animal,
little more than an inch and half in len2;th,
and about two lines in thicknefs, of which
the colour is a cineritious ground, interfperfed
with black fpots ; my obfervations upon this
fpecies were made three years after thofs
which are related in the pre fen t chapter.

I have hitherto related my remarks con-
cerning the generation of frogs, toads, and
newts, in fuch a m.anner, that it does not al-
ways appear, whether I have made fjch a
number of obfervations and experiments as is
necelTary, in order to obtain fefe and conffant
refults. Now the reader may be affured, that

1 have

j8 DISSERTATION I.

I have done this, not becaufe I was not iil
pofTeffion with a fufHcient number of fad:s,
but in oMer to avoid creating difguft by toa
frequent repetitions* I can alfo affure him,
that every fadl has been feen and examined a
great number of times, for I have been
taught by daily experience, that in natural
hiftory, truth can only be attained by the con-
ftant fuccefs of repeated experiments^

CHAP.

PlliSERTATlON t. 79

CHAP. VI.

l^EFLECTIONS.

XCIIL A /f Y principal intention in the five
^ preceding chapters^ was to re-
late fads unmingled with reflexions. I
would now deduce confequences, and lay be-
fore my readers fuch a train of reafoning, as
may contribute to the illuftration of the fub-
jedl, for this is the moft important part of
natural philofophy.

I. It is well known, that almoft all ani-
mals except man, have a ftated feafon for the
propagation of their fpecies. Thus the fe-
male cat receives the male in September, Ja-
nuary, and May. The fhe-wolf and fox in
January^ the doe in September and October.
' The fpring and fammer are the feafons ap-
pointed, for the amours of birds, and many:
fpecies of fiihes. The immenfe tribe of in-
fedls have likewife a determinate tim^e for per-
petuating their kind ; this is the fine part of
the year, and particularly autumn and fpring..
The laft mentioned clafs of being-s is fubied:
to a variation that is not obferved in the

others.

So DISSERTATION I.

dtiiers. Unufual warmth or cold does not
retard or forward the conjuncftion of birds or
quadrupeds; but a late fpring delays the
amours of infects, aild an early One forwards
them. Thus it is obferved, that in the fame
country, the iiifedls oil the mountains are la-
ter than in the plains.

xci V. The variations of heat and cold have
the fame effedl upon the amphibious animals,
that have been the fubjecl of my enquiries, as
upon infers. They too have, as we have
feen, a fixed time for their amours, but it
varies according to the warmth or coldnefs of
the feafon. If we compare my obfervations
on frogs and toads with thofe of Roefel, it
. will appear, that this order of animals begins
earlier to propagate the fpecies in the mild
climate of Italy, than in the rigorous tem-
perature of Germany. In his hiftory, he
fpeaks of a very fmall fpecies of aquatic toad,
which, from the beautiful flame-coloured
fpots that adorn the belly, he calls Bufo ig-
neus, as copulating near Nurimberg in June.
This ipecies is not found in the plains of
Italy, at leaft not in the Modanefe, the Mi-
lanefe, or the country round Pavia. I have
fometimes found it on the hills round Mo-
dena, the male embracing the female in May,
but I had not an opportunity of making my
. ' obfer-

DISSERTATION I. 8l

obfervations with fufficient accuracy. Af-
terwards, in my journey to Geneva and Swit-
zerland, in the fummer of 1779, I faw a great
number of thefe toads. In the courfe of my
excurfions with the amiable and learned Mr,
Senebier, on the eminences that almoft fur-
round that illuftrious and cultivated city, I
remarked, that there was not a lake or ditch
that did not afford reception to great num-
bers of thefe animals; they were generally
coupled, though it was then the end of July.
I, have moreover found them in Auguft, in
many waters in the vicinity of Berne, Bafil,
Zurich, and Lucern, and their amours were
then but juft iinifhed, as appeared from the
little tadpoles that had lately quitted their
mucus, and were fwimming about. Thefe
animals then copulate much eatlier in Italy,
than either in Germany or Switzerland. This
is not matter of furprize, for the Swifs can-
tons are well known to be the higheft part of
Europe, and by confequence muft be cold, as
I perceived among other proofs, which cannot
be properly introduced here, by the ripenin<^
of the corn, which is a month later than in the
plains of Italy, and by thofe trees, which with
us will not grov/ at all, or elfe only in the
higheft fituations^ thriving here wonderfully
Vol. IL G well

§2 DISSERTATION £

well in the loweft vallies, fiich for inftance as
the larch, the beech, the fir, &c.

I have obferved in the tree-frog, and fetid
terreflrial toad, in the river at Geneva, juft
the reverfe of what I had feen in the Bufo
aureus in Switzerland. In March 1780, I
remarked that the two former fpecies had
made their appearance, and v/ere coupled in
the ponds and other refervoirs of fine gardens
near that city, whereas in Auftrian Lombar--
dy, they had not yet quitted their fubterra-
neous abodes. The reafon why frogs, toads,
newts, and the numberlefs tribe of infers,
require a certain degree of atmofpherical
warmth, while other animals are not influ-
enced by it, is, I fhould think, becaufe the
latter have an internal fource of heat, which
animates them, even in the fevereft cold,
whereas the former are almoft entirely defti- ^
tute of any fuch fource. As therefore the
exercife of their functions depends on the heat
of the atmofphere, their amours alfo depend
• upon this caufe, and will of courfe be later ,
in cold than hot climates, and in both will
vary with the feafon.

xcv. II. It has been iliewn in the prece-
ding chapters, that the round bodies produ-
ced during the feafon of generation by the fe-
male frogs, toads, and newts, that fell un-
der

DIS'SERTATION I^ 8^

der my infpeclion, are not, as it has. been
univerfally believed, eggs, but real fetufes;
for they are never inclofed in membranous or
cruftaceous envelopes, like animals that come
from eggs, but are quite naked; nor do they
ever leave any ihell or membrane behind them,
after they have been impregnat-ed, except the
amnion, which is the cafe with all vivipa-
rous animals. It follows, that thefe fpecies
ought to be removed from the clafs of ovipa-
rous animals, to v/hich they have been re-
ferred by naturalifts and nomenclators, and
placed among the viviparous. There is a
circumftance here that*deferves to be noticed.*
All viviparous animals have this in common,
that their fetufes are at birth full formed, and
retain the lineaments which they then have
through their whole life : they are only more
unfolded. We are further certain, that they
have long before birth the form of the fpecies,
as is evident from human abortions, as well
as thofe of beafts. In like manner, animals
that come from eggs are formxed, not only
when they are hatched, but long before, as
we fee in the eggs of birds, various reptiles,
crocodiles, &c. If the eggs are broken and
examined, we perceive the fetufes more or
lefs advanced, provided they have been fe-
cundated and fet to hatch. I have made the

G 2 ' fame

S4 DISSERTATION Id

fame obfervation on the eggs of infeds; when
I found they were nearly hatched, I have fre-*
quently opened the pelhcle, and difcovered
the embryo formed, and endowed with the
power of motion. On the contrary, the fe-
tufes of the amphibious animals, that have
been the fubjedt of my refearches, are quite
fhapelefs at the time of exclufion, and have
only the appearance of globules ; it is not till
afterwards that the limbs begin to appear,
and that they affume the lineaments of the
fpecies. Now I think that upon refledlion,
I can affign the phyfical caufe of this ftriking
difference. The fetufes of other animals
have, indeed, at the time of birth, the cha-
ra(!lleriftic form of the fpecies, but they do
not acquire it for fome time after fecundation.
They are at iirfl: fliapelefs, as we fee in birds
in the egg, which, before they affume their
true figure, muft undergo the moil furprizing
changes, as has been fhewn by Haller, and
before him by Malpighi. Fetufes then, in
o-eneral, are not perfedly formed till fome
time after fecundation. Now in the amphi-
bious animals of v/hich I have been treating,
impregnation does not take place till the fe-
tus is excluded. It is, therefore, no wonder
that they are fhapelefs ; it is indeed to be ex-
pected, that they jQiould take the form of

tadpoles

DISSERTATION I." 85

t^idpoles after they are brought forth. And
we might conclude, that the globular figure
which thefe animals have, as'iong as they lie
in the ovaria, might perhaps be the univer^
ftl model for unimpregnated germs, if they
were not the prodadion of infinite wifdom,
and therefore probably infinitely varied.

xcvi. III. Though thefe animals are pro-
perly denominated amphibious, fince they
are capable of living both upon dry ground
and in water, yet, if we except the common
frog and the newt, they generally live out of
the water, and only repair to it in order to
propagate the fpecies^ and as if confcious that
their fetufes, if brought forth upon land
would irretrievably perifh, they invariably
depofit them in water, the only element where
they can be unfolded and grow. They do not,
however^f place them in any water that may
happen to be near : they are never to be fccn
in torrents or rapid rivers, but always in
ditches^ lakes, ponds, where the water Mag-
nates or runs but ilowly, The reafon of this
is very obvious. A rapid current would carry
the fetufes away, for they are fpecjfically
lighter than water, and by continually fl]a?-
king and dafliing them againft the banks and
Other obftacles, would deftroy the greater part.
The fame danger does not fubfift in ftagnant

G 7 waters

S6 DISSERTATION I.*

waters. Befides the tadpoles here find their
food, which chiefly confifts of water len-
til, a plant that does not grow in quick
ftreams.

Thefe animals then, as well as others,
carefully provide for the continuation of the
fpecies. In infe(fts in particular, thefe pro-
vifions are an inexhauftible fubjec^^ of admi-
ration. The curious obferver of thefe mi-
nute beings, is conftantly furprized by the.
care they take to depofit their eggs, where the.
young are fure to meet with proper food.
An immenfe number of both nocturnal and
diurnal butterflies and moths, come from ca-
terpillars that live upon various herbaceous
and woody plants. They never fail to depo-
fit their offspring precifely upon thefe plants.
There is not the leaft danger lefl: they fhould
miftake one vegetable for another. That
which comes from the caterpillar of the oak
never lays its eggs on the elm, and recipro-
cally. ^ The fame may be faid of other plants ;
for ihould fuch a miftake happen, the cater-
pillars would die for want of fit nourifhment.
Another clafs of infeds, the numberlefs and
various tribe of flies, aflx)rds equal caufe of
admiration : they all depofit their eggs in cer-
tain ftated places ^ fome in the pith or within
- the

DISSERTATION I. 87

the bark of trees, or upon the leaves., or with-
in the empalement of flqwers ; fome in the
ground or in water; fome upon dunghills,
in fepulchres or dead bodies, and others, in
fhort, within the body or upon the ftiin of
living animals.

Equal induftry and fagacity is confplcuous
in the race of cantharides, beetles, &c. And
to come to animals, more nearly refembling
thofe concerning which we are enquiring,
many fifhes, belonging both to fait and freih
water, conceal their eggs in places where the
water is ihallow, and confequentjy more
warmed by the rays of the fun ; hence the
young fry is fooner produced, Beiides thele
places generally afford more aquatic infecfts^
the food moft agreeable to fiflies. Turtles,
which are themfelves amphibious, furnifli
an example ftill more clofely conneded with
the fubjed; of thefe differtations, excepting
that they repair to dry ground, and conceal
their eggs in the fand.

xcvii. IV, In the four firfl chapters, I
mentioned the clofe embraces of the male
frogs and toads. This phaenomenon has
given rife to difcordant opinions. Vallifneri
thinks, that the compreffion contributes to
feparate the eggs from the ovaria, and to fa-

G ^ cilitate

SB DISSERTATION I.'

cilitate their entrance into the oviducfts (a).
Swammerdam, on the contrary, fuppofes that
it is more likely to prevent, than forward
their paffage through the oviduds, as it may
clofe their orifices. Hence he thinks, that
the male does not begin his embraces, till
the eggs have palTed through thofe canals {/?),
But this can only be determined, by opening
fome females at the commencement of their
amours. In fome fpecies, indeed, bare in^
fpedtion v^ill fhew, that the preffure made by
the fore-feet of the male, cannot contribute
to force the eggs out of the ovaria; for they
do not come forward upon the breaft, to
which the chief part of the ovaria lies oppo-
fite, but prefs againft the lower extremity of
the abdomen, as I have myfelf obferved in the
Bufo igneus of Roefel, and as indeed is evident
from his figure. I kept two females apart
frppi the male, but this did not prevent them
from difcharging their eggs. Hence it is
more than probable, that this would alfo hap-
pen in the fpecies, denominated by that na-
turalift, Bufo aquaticus allium redolens; for
the male dpes not prefs againft the breaft,
but like the igneous toad againft the abdo-
jnen of the female {c) . There feems, how-

(a) L.C. (^) Bibl.Nat, (c) See Roefel's figure,

ever

^

DISSERTATION I. S9

ever, fome ground for believing, that the em-
braces of the male may contribute to the ex-
clufion of the eggs, in thofe fpecies in which
he clafps the female round the breaft; as in
thofe frogs and toads, of v^hich 1 have de-
fcribed the mode of generation in the four
firil chapters. If the females of the aquatic
frog be kept feparate from the male, I have
found, that they do not difcharge their fe-
tufes (vii). Here then we muft conclude,
that the embraces of the male influence this
function.

Now I know not how this influence can be
exerted, except by the preffure made againft
the breaft, by which the fetufes are forced
out of the ovaria, and get into the m.ouths of
the ovidudls. But in the tree-frog, not-
withftanding prefllire is made againft the
breaft, it does not contribute to the defcent
of the fetufes, fmce they get into the uterus
before the male begins his embraces (xxvi).
When I wrote the hlftory of the terreftrial
toad, with red eyes and dorfal tubercles, I
knew not w^hether the female could bring
' forth without the male ; and I only faid, that
his embraces begin before the fetufes quit
the ovaria (xlii). I afterwards kept two
females in a veffel full of water, which,
without the approaches of the male, dif-

charged

9^ BISSERTATI O vN I^

charged their long and vifcid cords, but the
fetufes all perifhed for want of fecundation.
If we now compare the fads related, in this
paragraph, we fhall find, that Swammerdam's
opinion is not univerfally true ; for although
the embraces of the male are pofterior to the
defcent of the fetufes into the uterus in the
tree-frog, yet this does not happen in the
aquatic frog and in toads. Secondly, it will
appear, that the ftrong compreffion of the
male is very far from being always, as Vallif-
neri imagined, the caufe of the feparation of
the fetufes from the ovaria. We cannot
therefore on this, any more than on num-
Iberlefs other occafions, lay down any general
rule, but muft be attentive to the variation
of Nature, in the endlefs multiplicity of her
operations. '

xcviii. V. I ihall, perhaps, be afked to
point out the caufe of the male's perfeverence
in his embraces, which in fom.e cold coun-
tries laft above forty days, as Swammerdam
obferved in Holland. It may alfo be en-
quired, why thefe animals, during their a-
mours, not only abftain from food, but dif-
regard their own fafety, for at this time they
will not make any efforts to ayoid being

taken,.

I can

DISSERTATION I. 9I

I can ailign no other caufe, but that phy-
^cal neceffity which compels the individuals
of different fexes to approach each other at
this feafon. Under the dominion of this in-
fluence, which, in thefe amphibious crea-
tures, as in other animals, is probably more
ftrongly felt by the male than the female, they
go in queft of each other and copulate. They
muft continue coupled till their mutual ne-
ceffities are fatisfiedj this neceffity, in the
female, confifts in the expulnon of the fe-
tufes, and in the male, in the emuffion of fe-
men ; for the amorous impetus is occafioned
and exalted by this fluid, with which the
fpermatic veffels are gradually filled during
their embraces. Their pertinacity may have
indeed another origin; they may be afraid,
left if they fhould quit their fem.ale, fhe ihould
be occupied by another male -, we know that
the brutes are not exem^pt from jealoufy^ and
I have had occafion to remark, that it is par-
ticularly vehement in thofe of which we are
fpeaking. Their amorous ardour, which, at
this feafon, feems to be their only feeling,
may render them infenfible to the call of
hunger and to danger. - The long adhefion
of the male to the femiale, and the negledl of
themfelves, is not peculiar to frogs and toads,
but extends to various other animals, as we

every

92 DISSERTATION I.

every day obferve in infeds, and in fome ani-
mals of coniiderable fize; as in the turtle, of
which naturalifts have obferved, that the
male and female continue attached to each
other for feveral days ; and in this fituation,
the fifhermen eafily take them together.

xcix. VI. This bhnd ardour of the male,
has furniflied me with an opportunity of at-
tempting fome uncommon experiments, with
an account of which, I hope my readers will
not be difpleafed. In paragraph xli it is
faid, that if a couple of the fpecies of toad
with red eyes and dorfal tubercles, happened
to efcape out of my veffels, when coupled,
the male did not quit the female, not with -
ftanding ihe got to dry ground. I was fur-
ther defirous of knowing, whether a fepara-
tion could be effeded by violence, I there-
fore fufpended a male, by a thread tied to one
of his hind feet, for a quarter of an hour; he
woulci not, however, loofe his hold, not-
withftanding the long continuance of this vio-
lent attitude, and the weight of the female,
which was fo much larger than hjmfelf. I
next pricked him with a needle in the hind
legs, the thighs, the back, fides ajid head,
till the blood ilTued out at every pundqrp.
He would mo\^ and writhe, and ftretch out
and ^ontra«3: his body, but di4 not quit his

hold*

DISSERTATION I. 93

hold. I afterwards cut the body in various
parts with fcillars : but this expedient was
ftill ineffed:ual; nor v/ould he foriake his
fituation, when I cut away fmall pieces of
fleili; I even amputated a thigh without ef~
fed:, and it was not till after thirteen hours,
that the male, after fo much torture, parted
from the female, and expired the fame
inftant.

I put another male to this female, and as
foon as he had clafped her clofely, cut off
both his thighs without caufmg a feparation :
and what is more furprizing, the fem.ale be-
gan to difcharge the cords three hours after-
wards, and the male, with his blood flowino^ ^
all the time, continue to impregnate them
with femen, till the whole was difcharged.
The impregnation w^as effeftual, and, as
ufual, the greater part of the fetufes were
evolved.

I feparated the male of another couple
bv force, and then cut off his two thighs.
He was left with the female, that it mio-ht
be feen, whether he would refume his em-
ployment j an event which actually took
place, but he died before the exclufion of the
cords.

My laft experiment confifted in cutting off
the fore-feet of a male, and putting him to a

female.

94 DtSSERtAtlON i.

female. Now the fore-feet enable the male
to clafp the female fo clofely. The fubjea*
of my experiment inftantly leaped upon her
back, as if he had fuffered nothing, and
maintained his pofition, embracing her with
his bloody flumps, till he had fprinkled the
cords with feminal fluid.

c. I will not enter into the particulars of
other like experiments, that were made upon
the fetid terreftrial toad and frogs. I will
only obferve, that they coincided with thofe
I have related : the amputation of the limbs
neither preventing the embraces nor fecun-
dation. Nay, even the decapitation of a frog,
did not prevent either the one or the other*
It is well known, that thefe animals are fo te-
nacious of life, that this operation does not
immediately take it away. That of which I
am fpeaking was thrown into convulfions, but
neither the fore-feet nor legs quitted the breaft
of the female, which brought forth her fe«
tufes in an hour and three quarters, and I
was an eye-witnefs of the male's befprinkling
them with femen ; that they were fecundated,
there can be no doubt, fmce they came to life
at the ufual time. As foon as he performed
this operation, he deferted his fituation, and
died four hours afterwards.

The

Dissertation i. 95

The toad mentioned in paragraph xciii,
was alfo the vidlim of an experiment of the
fame fort* In AugufI: 1779, at Genthod, the
dehghtful villa of Mr. Bonnet, I cut off both
the thighs of a male of that fpecies, while it
was embracing the female; but without ef-
fefting a feparation, which did not take place
till many hours afterwards, a little before the
death of the animal. Befides Mr. Bonnet,
Mr. John Trembley was prefent at this ex-
periment. 1 was alked, whether this perti-
nacity of the male was the effedl of ftupidity,
infeniibility, or amorous ardour. Though
this appeared to be one of thofe quefiions, of
which the determination requires, that one
fliould enter into an animal without at the
fame time becoming one ; yet I helitated not
to fay, that I thought, as I ftill do, that this
perfeverance was lefs the effed: of obtufenefs
of feeling, than vehemence of pafiion, which,
as we have {cQUy renders them infeniible to
the call of hunger, and carelefs of their fafety
(xcviii). Such a degree of ftupidity is not,
I think, coniiftent with the great irritability
of thefe animals, and the figns they fhew of
acute feelings, v/henever they are v/ounded,
or have their limbs cut off during their
amours.

CI. vir.

9^ DISSERTATION i.

CI. VII. Swammerdam, In his account of
the g^eneration of frogs, fuppofes, that th^
eggs do not immediately pafs from the ovaria
into the oviduds, but that they pafs lirft
through the abdomen. He refts his opinion
upon the inftance of a frog, in which he
found the eggs partly in the ovaria, and
partly in the abdomen, befides thofe Virhich
were already in the oviduds and uterus. Roe-
fel, fpeaking of the dark-brown terreftrial
frog, fays, that he has found many eggs in
the abdomen, without, however, adopting
or rejedling the opinion of Swammerdam.
Of thefe eggs, or more properly, of thefe
tadpoles, lying loofe in the cavity of the ab-
domen, I have already fpoken (lxvii); but
if I may confefs what I think, I have no in-
clination to accede to the opinion of the Dutch
naturalift. I fhould imagine, that if the fe-
tufes vv^ere to pafs through the cavity of the
abdomen before they entered the ovidufts,
they would frequently be found there in fe-
males during copulation, fince they are fo
often found in the oviducts and uterus. Yet
the contrary is true. I wiih to avoid the
charo-e of oftentation, w^hen 1 obferve, that
having kept an account of the number of
frogs and toads, which 1 have opened at the
time of their amours, for this and the fol-
lowing

DISSERTATION I. 97

lowing dillertation, I find that it amounts to
2027; nor did I ever find the fctufes in the
cavity of the abdomen, except on three oc-
cafions, of which two are mentioned in pa-
ragraph Lxvii, and the other in cxxii. I
am much more difpofed to believe, that fe-
tufes pafs immediately from the ovaria to the
oviducts. Hence I think, that if ever they
get into the cavity of the abdomen or thorax,
it proceeds from their never having got into
the oviducts, or from fome laceration, as is
intimated in paragraph lxvii. Let the im-
partial reader determine.

cii. VIII. The fetufes, after having tra-
verfed the long and tortuous canal of the ovi-
dudts, are all collcifted in the uterus, whence
they pafs into the redum, and then out at
the vent. The difcharge, in one fpecies of
toad, is aided, by the male. Placed as ufual
upon the back of the female, and clafping
her with his fore-feet, he waits impatiently
for the expulfion of the cord (in this fpecies
there is only one cord) ; at the inftant of its
appearance, he lays hold of the end with his
toes, and draws out a piece of the cordj this
manoeuvre is repeated till the whole cord is
extrad;ed. So intent is the male upon his
employment, that he may be taken and placed
upon the hand. And though this may caufe

• Vol. II. ' H fome

98 i:> T S S E ^ t A t t O N I.

fome interruption, yet he will foon re fume
his tafk with equal ardour. This informa-
tion is owing to a cafual obfervation of Mr.
Demours^ on the fmall fpecies of terreftrial
toad, as he denominates the animal, he faw
nothing from which he could colled:, that
the male bedews the eggs with femen, while
he is employed in extracting them {a) .

It is to be lamented, that the French ob-
ferver did not particularly defcribe thefpecies*
It is certainly different from either of thofe,
of which I have treated^ fince I could never
obferve, that the male, affifted in bringing
forth the young, while it was eafy to fee, that
he bedewed them with femen. Roefel, who
mentions this fadl incidentally, adds, that he
never obferved any fuch appearance : it might
likewife have been expeded, from the accu-
racy of the obferver, that he fhould have ta-f
ken notice whether the eggs were produdtive,
iince we might have hence colledted, whether
they are impregnated within the body of the
female. It were alfo to be wifhed, that fo in-
terefting an obfervation fhould have been re-
peated. In fhort, the fad: being folitary,
and happening unexpedledly, fliould have
been confirmed, and the narration ought ra-

(a) The reader will find this very curious cA>^fervation re-
lated at full length in the Appendix. T.

ther

DISSERTATION I. 99

ther to awaken than fatisfy the curiofity of
the philofopher.

cm. IX. Daily experience (hews, that m
an immenfe number of animals, fecundation
takes place within the body of the female.
It might perhaps be thought, that we are
warranted to conclude, from analogy, that
this is an univerfal law of Nature. And it
has accordingly been admitted as fuch by
vulgar reafoners. But as on many other oc-
cafions, when the law was fuppofed to admit
of no exception, fo on this, analogical argu-
ments have been found to difagree with ex-
periment. Swammerdam firft fhew^ed, that
impregnation is effeded without the body of
the female in one fpecies of frog ; and Roefel
extended this difcovery to another amphibious
animal of a fimilarkind, I have had the fa-
tisfadion to difcover this external fecunda-
tion in other Ipecies of frogs and toads^ and
have, moreover, clearly beheld the fecundat-*
ing liquid ilTuing from the male, and falling on
the fetufes, after they were expelled from the
uterus of the female (Chap. I> II, III, iV)a

CIV. But we"^ know> that befides the fpe-
cies, in which it has been found that im-
pregnation is external, there are many others
included under the genus of frogs, as w^ell
as that of toads, both European and foreign.

H 2 We

100 DISSERTATION I.

We iliall be convinced of this, by opening
any modern nomenclator, as Linnaeus for
inftance. What then are we to conclude,
concerning the mode of fecundation in them I
From thefe conjeclures we may be wilUng
to believe, that it is the fame in the fpecies
that have not been examined. But we can-
not be certain without experiments. Among
thofe, which in this refped; require to be
examined by the naUfirahft, the famous toad
of Surinam, denominated by the natives
Pipa or Pipal {a)^ fo remarkable for its pro-
perty of bringing forth the young at the
back, would, in my opinion, deferve the
preference.

The celebrated Merian, who, with courage
truly heroic, went from Holland to America,
towards the clofe of the laft century, to ob-
ferve the infedls of that unwholefome climate,
firil made us acquainted with this animal.
jIt was afterwards examined by the acuteft
naturaliils, by Ruyfch, Folkes, and Baker,
and found exactly to agree with the defcrip-
tion left by that illuftrious lady. Its back
has cavities or cells, each containing a young
toad. 1 had myfelf the fatisfaclion of feeing
this rare and indeed lingular phasnomenon, in
the public Infdtute of Bologna, and to ftill

(^') Pipa (Rana) Digltls anticis muticis qaadridentatis,
pollicis UDguiculatis. Linn. S. N. T. i.

greater

DISSERTATION I. lOI

greater advantage lail: year at Geneva, in
company with my refpedable friends Bon-
net, Senebier, Abraham and John Trembley.
Nay, the poffeflbr, who had many years kept
it in fpirits of wine, obhgingly afforded Mr.
Bonnet and myfelf an opportunity of making
a number of obfervations upon it 3 and above,
all, to examine at leifure the dorfal cells,
which were very numerous, and of which
each contained a fetus. Thefe obfervations,
together with others, which rny illuftrious
colleague made after my departure from Ge-
neva, may be found in a Memoir printed in
Rozier's Journal, which at once fhews the
learning and good fenfe of the author, as well
as his impartiality with refpedt to his own
opinions. Having denied, in his CG7'ps org a^
niseSy the exiftence of the cells, on the au^
thority of a celebrated profeffor at Leyden (^),
he not only confeffes in the Memoir, that
they are to be found, but defcribes them in
a manner fo particular, as to remove all doubts
concerning their exiftence. He concludes
with propofing feveral queftions, calculated
to illuftrate the natural hiftory of this won-
derful native of Surinam, which is yet dark
and imperfect. It is eafy to fappofe, that the
Genevefe philofopher would not overlook

{a) Mr. Allamand,

H 3 what

102 DISSERTATION I.

what relates to the manner of impregnation -
But we cannot hope for the fokxtion of this,
any more than the other queftions, except
upon the fpot where the pipa hves, and pro-
pagates its fpecies, if we cannot naturahze it,
as Vallifneri naturaUzed the cameleon of
Africa.

But befides frogs and toads, it is fuppofed,
that fecundation is external in fcaly fifhes,
"When the female has laid her eggs, the male
is faid to go in queft of them^ and fprinkle
them with femen. There is then no real co-
pulation between thefe animals, though the
male approaches the female at the feafon of
their amours, and is fometimes feen to rub
his belly againft that of his mate; this ap-
pearance takes place, becaufe the male im-
pregnates the eggs at the inftant they fall
from, the female. This is the opinion of Buf-
fon {a) ; and the manner in vv^hich he delivers
it, would lead us to fufpecl, that he had the
moft certain proofs of it, though he has in
truth no better foundation for it, than the
notion which was generally prevalent till the
time of Sv/ammerdam {/?), that the cetaceous
clafs impregnates the eggs v^ithout copula-
tion. This notion was not, I think, fup-

W Nat. Hill. T. 2. p. 313, (^) Bibl. Nat.

ported

BIfiSERTATlON I. lO^

ported by any obfervation upon which reli-
ance could be placed. Hence it is no won-
der that other naturalifts, and among the reft
the illuftrious Haller, fhould incline to be-
lieve, that fiflies really copulate for feveral
reafons, which cannot properly be recited
*here, but may be k^n in his great work.
Though thefe reafons have far greater weight
than the bare affertion of BuiTon, yet I can-
not think them decifive, as they are deftitute
of fads, by which alone the problem can be
iblved.

The mode of fecundation In fifhes is very
extraordinary, according to Linnaeus^ he fup-
pofes, that the female purfues the male while
he is emitting the femen, and devours it^ and
and thus is impregnated {a). In the time of
Vallifneri, there lived at R.ome a phyfician,
who taught that pigeons, fparrows, and many
other animals, were fecundated by the
mouth (^). Both thefe opinions are palpably
falfe. Female iifees have, indeed, been ob-
feiVed to fwallow the femen, not becaufe it
then ferves to impregnate them, but fimply
for food. The male devours it with equal
greedinefs for the fame reafon. The fame
obfervations are applicable to the eggs,

(a) Sponf. Plant. (^) Vallifn. op. infogl. T. 3.

H 4 cv.

104 DISSERTATION I.

cv. Hence it appears, that we know not
certainly the mode of fecundation in fifhes.
The element they inhabit, is fo much more
difficult of accefs than the land and air, that
we cannot wonder the natural hiftory of fifhes
ihould be fo little advanced. Having often
micditated upon this fubjedt, which is yet
among the myfteries of nature, I have been
ftruck by a thought, which my other occu^
pations have not yet permitted me to bring to
the teft of experiment. I willingly lay it
before my readers. The golden filhes of
China (a) are nov7 very common, Italy in
particular abounds with them, there being
fcarce a pond that is not fupplied with them.
The beauty of their colours induces many to
keep them in veiTels in their apartments.
The amours of thefe iifhes happen feveral
times a year, and as they have little timidity,
they do not deiift from their employment
when the obferver ftands clofe to them. The
reader is by this time in polTeffion of my ideas.
Let thefe fifhes ^be carefully watched when
they are propagating their fpecies, and we
fliail foon know, whether they really copu-
late, or whether the m.ale darts his femeii

{a) Cyprlnus auratus, pinna ani gemina Cauda tranfverfa
Hfurca. Linn. S.N. T. i«

' ^ Upon

, DISSERTATION I. 105

upon the eggs after they are difcharged, or,
in fl)ort, whether fecundati@n takes place in
any other way. If it is external, the afper-
iion of the femen cannot efcape the attentive
obferver, as it is of a turbid colour. I will
not flay to point out the means of afcertain-
ing whether the eggs are fecundated, and in
what manner, as the reader may gather them
from the preceding obfervations on the gene-
ration of amphibious animals.

cvi. Recent obfervations feem to have
eftabliilied the certainty of external fecunda-
tion in bees. If the ingenious obfervations [a)
of Mr. Debraw may be relied upon, the eggs
of this induftrious infed: are impregnated af-
ter the queen has difcharged them. She, as
it is well known, depofits them in the cells.
The Engliih naturalifc obferved, th?t when
they are accompanied with a whitifh liquor,
which the male voids from the poflerior part
of his body^ they never fail to be produdive ;
but when this liquor is not prefent, they are
fure to periili. The author kept an hive
without drones. The queen laid her eggs,
as ufual, but as they were not impregnated
with the white liquor of the male, they pro-
duced no young.

{a)' Philofoph. Tranf. Vol. lxxii.

The

2 00 DISSERTATION I.

The experiment was varied in the follow^-
ing manner. An unimpregnated hive v^as
divided into two parts, of which one was fet
under a glafs-bell; in this was a queen, to-
gether v/ith working bees, but without males,
the eggs were not produdtiye ; but the con-
trary happened in the other part of the hive,
which was Ukewife fet under a glafs-bell, and
contained, befide a queen and common bees,
a quantity of males. And the eggs were im-
pregnated by the white liquor which the males
void in the cells containing eggs. The dif-
fecftion undertaken by the Engliih obferver
proves, that this liquor is the true femen;
for he found it in thofe vefTels of the male,
which are univerfally fuppofed to be appro-
priated to the reception of the feminal fluid.

From this it appears, that the two natu-
raliPcs, who have written fo well concerning
bees, have committed miflakes. Swammer-
dam thinks, that exhalations from the males
are abforbed by the female, and ferve to fe-
cundate the eggs ', while Reaumur has been
led by deceitful appearances to fuppofe, that
thefe infedls perpetuate their kind by real co-
pulation. Moreover, the fufpicion enter-
tained by the celebrated Maraldi, is com-
pletely verified; this writer, in his obfer-
vations on bees, conjeftures, that the eggs

are

DISSERTATION I. \ lOj

are impregnated after they are laid, by the
whitilli matter above defcribed; he, how-
ever, w^as not dihgent to enquire further.

From what has been faid on external fe-
cundation, it appears, that the number of
animals, in which we are certain that this
mode takes place, is very inconfiderable. We
may pre fume, that the induftry of obfervers
will increafe it, for many other difcoveries
have been extended to a multitude of fubjedls,
though they at firft feemed to be confined to
a fingle fpecies.

cvii. X, Fecundation in nevv^ts is accom-
panied with circumftances, that are not com-
mon to other animals, and deferve to be con-
fidered. The fetufes (for the elongated
bodies, fuppofed to be eggs, are only young
newts not yet unfolded, lxxxvii), are im-
pregnated within the body of the female.
But the male does not introduce into her any
part that characterizes the fex, for, in truth,
he has not any fuch part; he only darts his
femen into the water; the femen gets into
the anus of the female prepared to receive it,
and thus fhe is fecundated. And here occurs
another lingularity that deferves to be no-
ticed. According to the general opinion of
the beft anatomifts and phyliologifts, the
pvaria are the feat of fecundation; but this

cannot

loS BISSERTATION I,

cannot be the cafe in the newt. When the
feminal fluid gets to the inferior orifice of the
ovidudls, it cannot poffibly pafs any further,'
for its paifage is flopped by the fetufes, which
now occupy more or lefs of thefe canals, and
are generally thickeft at the mouth. The
feminal fluid then flops here, and moiftens
the fetufes as they come forth. Thefe are
the ojily ones that are fecundated; but they
are fucceeded by others, which are in like
manner fecundated by new emiilions of fe-
men, and fo on till all are im.pregnated. I
fuppole the reader to recoiled paragraphs

LXXX, LXXXI, LXXXII, LXXXIV, LXXXV.

upon which thefe deductions are founded.

cviii. XI. Though the chief objed: of
this diflertation is generation, yet I have
hitherto confidered it in a few animals only.
I fhall now extend my ideas, and make ufe
of the data which my experiments afford, as
principles that will prevent me from falling
into error in this intricate enquiry. The
moft celebrated fyflems concerning generation
may be reduced to two : the one attempts to
explain the formation of animated beings me-
chanically ; the other fuppofes, that they are
already formed and pre-exifting, and that the
a6l of fecundation only unfolds them, and
renders them vifible* Thofe who favour

this

DISSERTATION 1.

109

this fecond fyflem, are divided into two par-
ties; fome naturalifts being of opinion, that
the fetus pre-exifts in the female, and others
in the male. It is generally known, what
eiForts the eloquent BufFon has made to brinfy
the former fyflem (which is called the fyflem
of Epigeneiis, and is of more ancient date)
into repute, by means of his famous organic
■molecules. The powerful oppofition that has
been made to this fyflem, is alfo well kilown.
It has been ably refuted by the great Haller,
not only in his phyfiology, but alfo in a fepa-
rate publication, entituled RefieBions on the
Syjiem of Generation of Mr, Btiffon, The ar-
guments adduced by Mr. Bonnet in his Corps
organifes, are not lefs cogent. Obferving,
however, that the objecftions of both Haller
and Bonnet, though of great moment, are
not dired:, fince thefe writers have not en-
quired into the exigence of the organic mo-
lecules, which conflitute the bafe of Mr.
BuiFon's edifice, I conceived it neceffary to
enter into an examination of them, and have
found that this fyflem, like all his other fa-
vourite hypothefes, is the produd: of his fer-
vid fancy, which fo repreients fliadows, as
to make them appear like realities to thofe,
who have not a great fliare of difcernment.

I flatter

no DISSERTATION I,

I flatter myfelf, that my EfTays {a) prove the
truth of my alFertions.

The preceding obfervations on amphibious
animals, furnifli another irrefragable argu-
ment again ft the French naturalift. He thinks
that the fetus does not exift before fecunda-
tion, but is formed during this ad:, for then
the organic molecules, which are, according
to him^ the eifence of the femen of the male
and female, meet and combine in the uterus^
and by virtue of certain relations, are model-
led into an organized body. But my obfer-
vation on frogs, toads, and newts, are dia-
metrically repugnant to this imaginary theory.
They prove, that the fetus exifts in the fe-
male long before impregnation (xvin, xix»

XXX. LIV, LV, LVI, LVII. LXXII. XCl)„

Nov/ this is probably the cafe in other ani-
mals. My experiments, indeed, were all
made upon animals of cold blood j and this
circumftance may afford room to doubt> whe-
ther the conclufion is to be extended to thofe
of warm temperature. But all fufpicion muft
be removed, now the fame obfervations have
been made upon this clafs. I allude to this
luminous difcovery of Haller, who has fhewn,
that in birds the young exifts in the female

{a) Dpufcoli di iifica animale e vegetabile. Modena 1773c

before

tJiSSERTATIONI. Ill

before fecundation; but as this difcovery is
very generally known, it will be unneceffary
to relate it here. As then we have, both in
the clafs of cold and that of hot animals, in-
ftances of the pre-exiftence of the fetus, I
can fee no reafon, why we fliould not apply
the obfervation to the reft. We have at leaft,
till the contrary fliall be proved, good grounds
for believino; that this is the cafe.

cix. But thefe obfervations lead to other
confequences. I have remarked, that thofe
who admit the pre-exiftence of the fetus, are
divided into two parties, of which one be-
lieves, that they lie in the female, the other
in the male (cviii). According to the latter,
the fetufes are the worms that float in the ie-
men, and pafs, during coition, from the
male into the female. But the falfity of this
opinion is now obvious. In paragraph viir.
I obferved, that after the oviform corpufcles,
or the mature fetufes of the green aquatic
frogy have defcended into the uterus, the
ovaria contain others of a fmaller fize, which
ferve the year following to continue the fpe-
cies. The like remark was made (lxvi
and Lxxxv), concerning the fetid terreftrial
toad and w^ater-newt. I may now add, that
I have difcovered the fame thing in the other
amphibious animak mentioned m this work;

fo

112 DISSERTATION I.

£o that we may fafely lay, that the little fe-
tufes are to be found in the ovaria, at leaft a
year before thefe animals feek each other for
the purpofe of generation : they do not, there-
fore, pafs from the male to the female during
the a<ft of fecundation.

Here it is proper to anfwer a queftion that
may be a{ked. It appears from the obferva-
tions of naturalifts, that thefe feveral fpecies
of amphibious animals begin to propagate
the fecond year. And it is probable, that
they continue to do this as long as they live;
that is to fay, for a confiderable feries of
years; we have at leaft Roefel's authority for
believing that frogs live ten years or lon-
ger [a) 'y and itfeems likely, that toads come
near them in this refped:. Let it then be
fuppofed that they propagate for nine years.
The females will exclude nine fucceiTions of
fetufes. If v^e examine the females during
the firfl: year of their growth, we fhall not
find any fetufes in the ovaria. We are not
able to diftinguiili any before the fecond year,
when two fets appear, viz. the mature ones,

(a) If any conclufion may be deduced from the curious ac-
count of a toad in the Appendix to the Britifh Zoology, the
term here affigned is too (hort. The individual there defcribed
is faid, if I remember right, to have lived at leaft thirty-fix
years. T.

thofe

DISSERTATION I.' II3

thofe which are to be brought forth that year,
and the immature ones, which will be pro-
duced the fucceeding year. That year the
third fucceffion of fetufes becomes vifible,
and the fourth year the fourth fucceffion;
and in this manner one fucceffion only every
year. Now it may be alked, whether thefe
orders of fetufes, which fucceffively appear in
the ovaria, pre-exifted in them without being
viiible; fo that they are only evolved, and
rendered confpicuous by time, or rather w^he-
ther they are formed in fucceffion, a new
order being annually generated.

I fhould reply without hefitation, that as
it is by no means proved, notwithftanding
the eitorts of the modern favourers of Epi-
genefis, that any fuch formation of organic
bodies takes place, either in the animal or ve-
getable kingdom, and as all Nature abounds
with fuch evolutions, according to the ac-
counts of the moft judicious philofophers of
this age, it is natural to fuppofe, that thefe or-
ders of fetufes, which annually make their ap-
pearance in the ovaria, are not fucceffively
generated, but co-exifted with the female,
and are only unfolded, and rendered vifible in
progrefs of time, by the fupplies of nutri-
tive liquor that come from the female. This
co-exiftence of fucceffive orders of fetufes.

Vol, II. I which

Ii4 DISSERTATION !•

which become vifible in the ovaria, is ana-
logous to that which takes place in the hmbs.
Tadpoles have at firft no legs. Thefe parts
appear only when they are about to affume
the lineaments which characterize the fpecies.
ShaU we therefore conclude, that they do
not exift at firft, but are generated when the
t^adpoles approach their metamorphofis ? Is it
not infinitely more philoiophical to fuppofe,
that the limbs co-exift with the tadpoles,
and are invifible, only becaufe they are too
finall to ftrike the fenfes ? And if it is reafon-
able, to adopt this opinion concerning the
limbs, fliall we not alfo admit it with refpedl
to the fetufes of thefe animals ?

ex. XII. If I paffed over in filence the
fingular, and I think, new opinion of Mr.
Gautier, concerning the generation of frogs,
I fliould deviate from the fincerity which
every philofopher ought to pradtife. In a
publication entituled, Qbfervatims fur V hi/^
torie 7iatiirelley fur la phyfique, &c. after
fpeaking of fome fmall worms, which he
found in a yeficle in the cavity of the abdo-
men of the male, he adds, that they are the
real efficient caufe of generation. I muft
quote his own expreilions: La grenouille
male montee & fortement attachee fur la fe-
melle attend les inftans que les oeufs s'ecou-

lent

DISSERTATION I. II5

lent de la femelle: il jette alors fes embrions
tels que je les ai apperfus, ils s'attachent aux
oeufs, & s'en nourriffent pendant quelques
jours, jufqu'a ce qu' ils foient en etat de fe
nourrir d'alimens plus grofliers. Ces em-
brions confervent la meme figure qu'ils
avoient dans la veficule du pere, pendant Tef-
pace d' environ un mois, temps au quel ils
quittent cettent figure, comme font les vers
a foye dans le cocon. Ils developpent leurs
pattes pofterieurs qu'ils ecartent enfin : ce font
ees pattes qui unies dans rembryon, for-
ment la queue du tetard embryon de la gre-
nouille.

As the book was publlfhed in 1752, 1 have
had fufficient time to examine the difcovery.
My firft ftep w^s to feek for the bladder con-
taining the worms in -fie abdomen of the
male. It was eafily found, being no other
than the urinary bladder, as may indeed be
colledled from the defcription of the author 1
in this I moreover found the worms; they
are about th© thicknefs of a thready of a yel-
lowiih white colour, v/ithout rings, a line
and a half in length; they are.almoft perpe-
tually in motion, and have one extremity at-
tached to the infide of the bladder. So far I
agree with Mr. Gautier; but I cannot,, with
him, confider the worms as the fetufes of the

I z frog^

tl6 DISSERTATION I.

frog, for the following reafons, which I
think decifive. They are like wife to be found
in the bladder of the female, whereas they
ought to exift only in the male, if they
were what the French naturalift fuppofes
them to be. Secondly, I have opened an im-
menfe number of frogs during the time of
copulation, but have by no means found thefe
worms in all of them. Thirdly, They never
exceed twenty in number, whereas the ' fe-
tufes, from my obfervations and thofe of
Swammerdam, appear to amount to about a
thoufand in every female. Fourthly, After
fecundation the male ought not to contain
any, but I have found that the number is not
lefTened. Fifthly, As thefe worms adhere
to the fuppofed eggs, and feed upon them
for feveral days, I muft have alfo ken them,
efpeciaily as they are vifible to the naked eye.
I can, hov/ev^, truly alTert, that notwith-
ftanding ail my attention in examining the
eggs, both externally and internally, I never
could perceive any veftige of them. I /hall
deduce a fixth argument from the artificial
fecundation fpoken of in the next differta-
tion ; which confifts in touching the fetufes
extradled from the females with the femen of
the male, though that fluid fometimes ap-
peared defdtute of living inhabitants, even

when

DISSERTATION I. II7

when examined by the microfcope. Thefe
reafons obhge me to reje(5l the pretended dif-
covery of Mr. Gautier. I will not pronounjce
it to be a mere fiction: I will rather fuppofe,
that fome fallacious appearance has mifled
him, in confequence o![^ his inexperience in
obferving frogs, and his ignorance concern-
ing their internal firafture, though that is
exceedingly obvious. That this is the cafe
every naturalift will perceive, from the paf-
fage in which Mr. Gautier affirms, that the
hind legs of the tadpole, by their union, form
the tail of this animal.

Baia che avanza in ver quante novelle
Quante mai diiTer favole o carote
Stando a;l foco a filar k Vecciikrelit?.

Thofe who fliall have the curio (ity to read
Ills book, will learn, that the female frog -
has no uterus, that the tongue is fixed to the
anterior margin of the palate, that the kid-
neys of the frogs are alfo the tefticles, &c.
It is not, therefore, matter of furprize, that
Roefel fhould treat him with ridicule, and
conclude, non folum itaque afferere audeo pa-
rum in anatomia Ranarum profeciffe Gautie-
rium, fed addere etiam non ambigo, ipfas
ranas eundem vix liabere cognitas. And
as the Parifian naturalift, in the relation of
his difcoyery, modeftly obferves, that if Py-

I 3 thagora^

il8 p I S S E R T A T t 0 N I."

tha^oras had made one ..qual to his, he
would have facrificed another hecatomb to
the Gods. The German obferver retorts;
Ego vero credidcrim, fi fieri poffet ut Gau-
tierius Pythagoras quae invenerit, enarraret,
hiinc ipfi non filentium biennii vel quin-
quennii, quod difcipulis fuis imponere folebat:^
fe4 perpetuuai elTe injunfturum.

CHAP.

©JCSSERTATION I. II9

CHAP. VIL

EXAMINATION OF SOME RECENT OBJEC-
TIONS MADE AGAINST THE SYSTEM OF
THE PRE-EXISTENCE OF TliE GERM IN
THE FEMALE,

CXII, T^R- Pirri, a celebrated phyilcian
^^^^ and philofopher at Rome^ is the
author of thefe objections. To a fenfible
work on the theory of putrefadtion, wherein
he declares in favour of the Count de Buffon's
fyftem of generation, he has prefixed Ibme
refled:ions concerning the reproduffion of
iOrganic bodies, in which he attempts to over-
turn the principal arguments of thofe who
adopt the hypothefis of pre-exiftence of
germs. In the firft place he quotes and at-
tacks two difcoveries, one made by Haller on
the chicken (cviii), the other by me on
frogs, and mentioned in my Profpeflius. Let
us bellow a little attention on both, and begin
with that which belongs to me. *' The
learned Abbe Spallanzani, a name now fo
dear to his country, fays he p. 7, has related
another fact not lefs intereiling than thofe

1 4 already

I20 DISSERTATION I,

already mentioned, nor in appearance lefs fa--
vourable to the dodrrine of Palingenefis, or
the pre-exiftence of germs in the eggs of the
female, and by which the importance of the
fundion of the male is very much leffened.
He watched the inftant when the eggs are
extracfted and fecundated by the male. Du-
ring this operation he killed the female, and
by the aid of the microfcope, that inftrument
which has fo often impofed both on our fenfes
and underftanding, he found, that both the
impregnated and unimpregnated eggs, which
lay in the uterus, contained a tadpole bent in
fuch a manner, that the tail w^as contiguous
to the head. The young animal was diftin-
guifhed by its black colour. In the impreg-
nated eggs it was alive and in motion, but in
the others it lay in a profound lethargy/^ It
v/as proper to tranfcribe the exprefiions of Dr.
Pirri, as they by no means agree with my re^
lation of the difcovery in the Profpedius*
The reader mull; allow me to quote my own.
words. After remarking, that the impreg-
nated and unimpregnated eggs of the frog are
perfedlly alike, and that the latter are not
produdive, I add, p- 51? *' but this is far
from being the cafe with the former. They
lofe their round fhape, and elongate without
fenfibly increafing in bulk, though they af^

ter wards

DISSERTATION I. 121

terwards manifeftly grow larger. The furface
of the whitifh hemifphere turns darker, and
upon the black hemifphere appears a longi-
tudinal furrow, terminated by two procefTes,
which become gradually longer, and take the
direcftion of the long diameter of the egg.
The furrow and proceffes grow, and in time
nearly burft out from the lide of the egg,
which yet retains the fhape of an oblong glo-
bule, with a prominence on one fide. Mean-
while the whitifli hemifphere dilates, and the
black one is inpurvated, w^hile the promi-
nence increafes in length, and it now appears,
though this is ftill m^ore diftindlly feen af-
terwards, to be the tail of the tadpole : the
curvature on the black hemifphere is dif-
covered to be the back, and the dilatation on
the oppofite fide the belly. The other ex-
tremity now takes on the figure of the head^
in the anterior part the vefl:ige of the eyes,
which are yet clofed, becomes confpicuous :
the two proceffes, by whicji the animal ad-
heres to bodies, however fmooth, come in
fight, as well as the rudiment of the aperture
of the mouth; and laflily the gills, through
which the blood may be fccn to circulate.

The animal does not yet £hew any figns of
life or motion, when it is pricked with a
needle, or ^fuddenly expofed to the rays of

the

122 DISSERTATION I.

the fun, even when collected into a focus,
though it is afterwards fenfible of thefe im-
preflions

Such are the phjenomcna which gradually
appear in fecundated eggs, whence it is evi-
dent, that thefe bodies are not, as it has been
generally fuppofed, eggs, but the tadpoles
themfelves concentrated and folded up.

It is therefore clearly proved, that the tad-
poles exiil before fecundation 3 but this in-
terefting truth may be more fully fhewed
thus : the fecundated eggs differ not m any
refpedl from thofe which have not been fe-
cundated, but the former are the tadpoles
concentrated and folded up, the latter mpft
therefore be the fame 3 wherefore the fetufes
of frogs exift before fecundation, and to be
evolved, want only the fecundating fluid of
thetnale/'

Upon comparing this paffage with the
quotation of Dr. Pirri, it is eafy to perceive,
that at the time of writing, he had not the
Profpeclus before him. Firft he advances
what is not true, when he afferts, that I made
ufe of the 'microfcope, ** that injirument
'which has fo often deluded both our Je?ifes and
underfianding\' except in the paffage where I
lay, that I examined the iniide of the egg
with the microfcope, I never fpeak of it,

having

DISSERTATION I. 123

haying had indeed no occafion to make ufe of
it; for the eggs are fo large, as to be capable
of being examined fufficiently by the naked
.eye. If even I had been obliged to have re-
courfe to this inftrument, I hope I fhould not
have incurred the danger which the learned
phyfician mentions. The microfcope has,
indeed, fometimes been the fource of error,
either when it was ill conftrudled, or in the
hands pf unexperienced perfons. But it has,
neverthelefs, when thcfe inconveniencies have
not been prefent, enriched, and every day
enriches natural hiftory with the moft im-
portant ducoveries. Whoever, indeed, ihall
que (lion this, will rifque the imputation of
being fuppofed deficient in common fenfe.

Secondly Dr. Pirri fays, that I found both
the impregnated and unimpregnated eggs to
contain tadpoles. Thefe words fuggeft an
idea very different from that which I have
expreifed. I do not fay, that I have found
the tadpole to exifl: as v/ell in the latter as the
former egg, but that both are nothing but
tadpoles. The expreffion of Dr. Pirri fup-
pofes the exiilenc€ of eggs, whereas mine en-
tirely excludes them.

Thirdly, The tadpole was, according to
the objeftor, fo bent, that its tail was con-
tiguous'

124 p I S S JE R T A T I O N I.

tiguous to the head, and it was diftinguifli-
able by its dark colour.

In my Profpedtus I do not fay that the co-
lour is entirely black, but that one hemfphere
of the tadpole, while it retains its round fhape
is black, and the other of a dirty white.
With refped; to the pofition of the tail, the
author is far lefs accurate ; for I never dreamed
of aiTerting, that the tail k bent towards the
head, but that it appears like a prominence
or appendicula, and increafes in length as the
ta.dpole grows. This is confined to the im-»
pregnated tadpoles; for the others have no
tail, though Dr. Pirri would make the rea-r
der believe, that I attribute this part alfo to
them.

Fourthly, I found this difference, ihat in
the impregnated eggs the tadpole was alive
and in motion, whereas in the others, it was
moticnlefs, and in a profound lethargy.

I fliall finifli thefe ftricStures upon the ex-
trad: VN^ith obferving, that I never mentioned
any profound lethargy in unimpregnated tad-
poles ; and fo far was I from feeing any mo-
tion in the others at firft, that I exprefsly
mention the contrary. Let the reader again
perufe the quotation from my Prpfpe<ftus,
and he will find that thefe ftriilures are

juA.

cxii. I

DISSERTATION J. 125

CXI I. I fhall now examine the objedions
of Dr. Pirri. They may be reduced to tv/o,
of which the following is the firfl:. My dif-
covery of the pre-exiftence of the tadpole,
refts upon an obfervation in which I fully
confided, as it has the authority of Swammer-
dam ; from whom we learn, that in frogs fe-
cundation does not take place in the uterus,
but without the body, fmce the eggs are
touched with the femen of the male, after
^heyare difcharged. The Roman naturalift,
relying upon the remarks of Roefel, fuggefts
various doubts with refpedl to this obferva-
tion, '* How, fays he, can we be certain
that the eggs of frogs are impregnated after
they are laid, when Roefel himfelf confeiGTes
the uncertainty of this, having feen an in^
ilantaneous contadt, which may afford room
for fuppoling, that the femen was thrown
into the uterus? (p. 15.)"

When I compofed my Profpedlus, I was
not unacquainted with the doubts of Roefel,
but I was aware, that they did not deilroy
the validity of the contrary obfervation, fmce
that is pofitive. Roefel himfelf was feniible
of this, and he does not, therefore, in fpeak-
ing of this momentaneous conjundiion, quef-
tion the fad: related by Swammerdam, a cir-
cumftance w^hich Dr. Pirri ought to have

known.

126 DiSSERtATibN f.

known. But farther, he does not only no^
queftion what Swammerdam tells, but
ftrongly confirms his obfervation in another
paffage of his work, where he fpeaks of the
generation of the green frogs. He fays ex-
prefly, that the male bedews the eggs with
his femen, after they have been difcharged
by the female. *^ Simulac autem femella
ova fua per anum emittit, mafculus eadem
fuo confpergit femine; id quod ipfe domi
me^ non folum vidi, fed iteratis etiam vici-
bus fieri non fine admiratione obfervavi (^)i
And to render this external fecundation fcill
more evident, he reprefents the male mounted
upon the female in their natural colours, the
eggs as they are difcharged, and the feminal
fluid bedewing them. Fig. 2. PL 13. It
might have been expected from the inge-
nuoufnefs of my opponent, that he fliould
not have fupprefifed this important obferva-
tion, or rather that he iliould have fpared his
objections. If he entertained any doubts
concerning the mode of generation in thefe
animals, I hope they will be difpelled by the
four firfi: chapters of this difl"ertation.

cxiii. In the fecond objeffion, I am ae-
cufed of a paralogifm in the relation of this
difcovery. In fpeaking of the pre-exiftenee

{a) Hift. Rar^r, p. 56,

of

1>ISSERTATI0N I. tl"]

of the tadpole, by the word tadpole I mean
the embryo of the frog, or the frog in a very
fmall Itate, difguifed under the appearance of
the tadpole. This offends Dr. Pirri, who
confiders the frog and tadpole as two diilincl
animals. He concludes, that '^ tomakeufe
of this fa(5l: as an unanfwerable argument
again ft the fyftem of Epigenefis, is a fallacy
th'-ii has eicaped the penetration of the Abbe
Si-'allanzani. It coniifts in confounding^ the
appearance of the tadpole with that v/hich
belongs to the frog; and falfely fuppoiing,
that the tadpole and frog are one and the
fame animal."

I was indeed appreheniive, on account of
my confined talents, that my book on animal
reprodudtions would contain miftakes, 'but
not that to w^hich my learned adverfary ob-
jedls. My confidence was grounded upon
Swammerdam, Vallifneri, R.oefel, and many
other excellent writers, who all agree in con-
fidering the tadpole and frog as the fame ani-
mah We know that many infeds pafs
through the three different ftates of worm,
nymph, and winged animal: and thofe who
are at all acquainted with natural hiftory
know, that thefe different ftates do not con-
ftitute three diftindl animals, but that the
fam.e animal aflumes thefe various appear-
ances;

128 riSSERTATiOrJ tl

ances ; fo that the infed: equipped with wings,
exifted under the membranes of the worm
and nymph, from which, when it is freed ,(
it iffues forth in a ftate of complete evolu-
tion. Swammerdam obferves, that what the
nymph is to the winged infedl, the tadpole is
to the frogi For he found the frog in mi-
niature under the difguife of the tadpole, and
the winged infed: under the cover of the
nymph. Both continue in this ftate only
till they are arrived at a proper period or fl^a'te
of maturity, when they throw off their old
habiliments, and affume their proper form^
From thefe obfervations I had reafon to con-
clude, that the tadpole and frog are identical ;
and this might have fufficed as a reply to the
objedlions of Dr. Pirri: my fuppoiition was
moreover founded on certain obfervations*
his was gratuitous. My efteem, however,
for this phyiician, who is advantageoufly
knovv^n by feveral other publications, and my
deiire to afcertain a fad: of fo great im-^
portance, induced me to undertake a more
particular and exad enquiry into the identity
of the tadpole and frog than that of Swam-
merdanj. To prove this completely, it is
neceffary to fhew, that the internal ftrudure
and organization of the parts of the tadpole
continues the fame in the frog. If we find

in

DISSERTATION I. 1 29

in each the fame fyften^ of arteries, veins,
nerves, and mufcles, if the heart, Hver,
lungs, and other vifcera be unaltered, if there
be no difference in the organs of fenfe and
the difpofition of the bones, there can re-
main no doubt concerning the identity of the
animals.

cxiv. Soon after Dr. Pirri's book came
to my hands, in the fpring of 1777, a feafon
very convenient for the purpofe, i began this
enquiry upon the green aquatic frog, of v/hich
I treat in the firft chapter. To be as brief
as poilible, I will only mention the bare re-
fult, beginning as foon as the internal ftruc-
ture of the tadpole can be examined, and end-
ing at the time when it takes on the appear-
ance of the frog. On the twenty-fixth day
the inteftines are diftinguifhable, though the
integuments of the abdomen, rolled up in a
fpiral, and in the region of the thorax ^ the
pulfation of the heart is perceptible. Upon
opening thefe cavities, v/e find the mefentery
refembling in thinnefs and tendernefs a fpi-
der's v^eb; along it wind fmall red ftreaks,
which, when viev/ed with the microfcope,
appear to be arteries and veins. The kid-^
neys, lungs, and liver are then very con-
fpicuousj to the laft vifcus is appended the
gall-bladder^ full of a tranfparent liquor

Vol. II. K with-

I^O 1>ISSERTATI0N 1,

without any bitternefs. The heart is conical,
and confifls of an auricle and ventricle; a
little nearer the head lies the bulb of the
aorta, which is divided into two branches
that are implanted in the mufcles of the
breaft. The defcending aorta is alfo vifible,
and the vena cava, together with the begin-
ning of their ramifications. The dorfal and
lumbar vertebras, as well as the cranium,
have nothing of the eonliftence of bdne, and
the brain is gelatinous, as are alfo the nerves ;
thofe arifing from dorfal vertebras are very
diiLinguifhable. The noftrils are open, and
the iris is of a golden yellow colour. If we
taice the eye out of the orbit and open it, we
fliall find the aqueous and vitreous humours,
and the chryflalline dens, which has fome
confidence and is verytranfparent* The gills,
which in more advanced tadpoles, appear on
the outfide of the body, are as yet lying un-
der the integuments of the thorax.

On the thirty- fill til day the vifcera are the
fame, but larger and more firm. The liquor
of the gall-bladder is ftill tranfparent, but
by this time fomewhat bitter. The arteries
and veins are of a deeper red, and by confe-
■quence ciore confpicuous. The cranium and
vertebrae begin to turn cartilaginous, and the

brain.

DISSERTATION I, I^I

brain, fpinal marrow, and nerves are not fo
gelatinous »

On the forty- lixth day, theie feveral parts
are further unfolded and firmer. The bile is
bitterer, and the rudiments of the hind leo:s
begin to appear. Somewhat too of the fore
legs may be difcerned, but they are as yet
buried under the integuments of the thorax.

The fore legs do not appear till fifteen or
twenty days afterwards \ for the time varies
in tadpoles that are brought forth at once.
In other refped:s the fl:rud;ure continues the
fame.

Nor does it eiTentially vary during the fub-
fequent days, when the legs being unfolded,
■and the tail growing Ihorter, and being at
length obliterated, the tadpole puts on the
form of the frog.

This happens about the eightieth day,
when the old integuments come away. And
now the animal becomes a true froe, differ-
ing from the adult only in fize. It does not,
however, differ from the tadpole, but has
the fame organs and vifcera, the fame fyftem
of arteries and veins and nerves, the fam.e
conformation of bones, with numberlefs
other parts which I fhall not defcribe, lefl
the reader fhould find me tedious. Thefe
new obfervations confirm the identity be-

K 2 tweea

132 DISSERTATION I*

tween the tadpole and frog ; they demon-
ftrate that Dr. Pirri, in combating this fup-
pofition, has contended againft truth. If
any remaining afFediion for this harmlefs mif-'
take fliould fuggeft to him, that the gills
and tail of the tadpole are not to be found in
the frog, and that the frog has four legs,
while the tadpole has at firft none, let him
-recoiled, that the chicken, at its iirft ap-
pearance within the egg, has the fhape of a
worm with a large head and long tail; that
the heart has afterwards the form of a half
rine ; that incubation continues fome time be-
fore the legs and wings fhoot, and that it lofes
the uitibilical cord when it breaks the egg {a).
And yet^ notwithftanding all thefe appear-
ances of metamiorphofis, no one, I believe,
has ever imagined the pullet in the egg, and
the cock to be different animals. And fo
much concerning Dr. Pirri's objeiflions to
w^hat I have advanced.

cxv. Let us proceed to that which he
has brought againft the difcovery of Haller.
Defirous of knowing the fentiments of this
<:^reat phyfiologift, between whom and my-
felf there had fubfifted a friendihip of long
continuance, I fent him Dr. Pirri's book,
but it came to his hands at a time when he

{a) Haller. Form, du Poulet.

was

DISSERTATiON I. I33.

was oppreffed with thofe maladies which
were foon to deflroy him. Inftead, there-
fore, of writing his fentiments at length, he
rephed in thefe laconic terms, Berne Nov. 5,
1777, '' Je V0U3 abandonfie ce M, Pirri; il
eft en bonnes mains, vous fcaurez aflez de-
fendre la bonne caufe de la Nature. II eft
toujours temeraire d'attaquer des experiences
par des raifonnemens." Thus he impoied
upon me the tafk of anfwering Dr. Pirri^,
and I would certainly have undertaken it, if
upon more maturely weighing the obiedlion^
and comparing it with Haller's difcovery, I
had not perceived, that I might fafely defer
it at leaft, if not entirely decline it, without
offending the objector himfeif. I v%^ould,
therefore, beg the ingenious naturaliil: to
read the relation of the difcovery oyer again
with greater attention; for from his extrad:
and T^p^Jy he appears to have overlooked
more than one elTential circumftance. This
will becomxe evident, if we compare the ex^
preffiqiis of the original with thofe of the
extra(fl.

'' The yoU; pf the egg, concludes Haller^
from his obfervations on the chicken, is a
continuation of the inteftines of the chicken ;
the internal coat of the yolk is continued with
the internal coat of the fmall inteftines and of

K3 tM

134 DISSERTATION I.

the ftoniach, and pharynx, and with the Ikin
and cuticle. The external coat is the exter-.
nal coat of the inteiline; it is continued with
the mefentery and peritonaeum. The cover
which enclofes the yolk, towards the end of
incubation, is the {kin itfelf of the fetus."
Me then reafons thus, " if the yolk is con-,
tinued with the fkin and inteftines of the fetus,
it muft have co-exifted with the fetus, and is
really a part of it. But the yolk exifted in
the female, independently of any commerce
with the male; therefore the fetus itfelf alfo
pre-exifted."

The fame great writer expreffes himfelf
v/ith ilill greater precifion in his phyfiology.
B. xxix. Seel: 2. Denique directa demon-
ftratio adeft, qua ofl:endes, certe in avibus,
pullum in matre fuiffe. Pulli enim intefti-r
num continuatur cum vitelli involucro &
adeo inteftini interior membrana cum epider-
mide anim.alis, exterior cum cute 3 denique
cum involucro vitelli eadein eft.

Dr. Pirri ufes the following terms, *' Hal-
ler having fhewn that the membrane of the
yolk, which pre-exifts in the impregnated
egg, is transformed by incubation into the
fmall inteftines of the chicken, concludes
that the chicken pre-exifts in the unimpreg-
nated eggs,"

Let

DISSERTATION I. 1^^;

Let the Roman phyfician determine con-
cerning the fideUty of his ov/n copy. To
this he adds another faft taken aifo from Hal-
ler, and endeavours to confute him. But
the author did not confider the latter as of
equal weight with the former, which, there-
fore, ought to have been faithfully quoted.

I am aware, that thefe ll:rid;ures cannot be
pleafing to Dr. Pirri, more efpecially thofc
which Ihew his inaccuracy in relating the
difcoveries of others. I would, therefore,
willingly have omitted -them, as well on ac-
count of the real efteem I entertain for his
merit, as fome degree of friendfhip I have
contracted with him fmce the publication of
his book; in confequence of which, I have
been ftudioufly mild in my expreilions, and
have oppofed things and not words to him.
But, when I w?.s treating this fubiecl, to
omit them entirely was impoiTible. I will
moreover obferve, that I do not confider thefe
inaccuracies as intentional, but as proceed-'
ing from want of refledion, or rather of lei-
fure; for he confefles, that he com.pofed his
confiderations on the reprodufbion of organized
bodies in a few days, I cannot, therefore,
but urge him afreili to examine thefe two
fads, which prove, that the fetus belongs
entirely to the female, at greater leifure, and

K4 . with

c

t^S DISSERTATIOIT 1."

with deeper attention ; I wifh that to thefe he
would add the further proofs I have adduced
in ihis and the following difTertation. That
he may be a good judge of thefe facts, lie^
mull moreover allow me to fay, that he
ought to be in poflefiion of the difficult art
of making obfervations and experiments with
fliiil. He may then repeat thofe w^hich I
have made, and will be enabled to give his
opitiion concerning them with greater free-
dom and fafety.

cxvi. The author likewife difapproves of
Mr. Bonnet's do(flrine concerning the invo-
lution of germs, though he does not diredlly
attack it, but declares that he does not fub-*
fcribe to it^ at which I do not wonder, be-
caufe the opinion of every one is free, and
Dr. Pirri manifefts too great a partiality for
the Eoigenefis of the illuftrious Buffon. I
was, however, not a little furprized, when I
came to read in page 32, a paffage of the Ge-
nevefe philofopher^ whence it v/ould appear,
that he is himfelf an oppofer of the fyftem of
Involution. My furprize was increafed, when
I learned that the evolution of bodies is, by
the confeffion of Mr. Bonnet himfelf, de-
duced from equivocal fads, and from pre-
mifes that by no means lead diredly to any
fuch cpnclulipn. I was iniligated, by thq

defire

DISSERTATION I. 1 37

defire of knowing how iny illuftrious friend
would reconcile thefe contradidions, to write
tp him at Geneya, making him at the fame
time acquainted with Dr. Pirn's fentiments
concerning my difcovery, and the organic
molecules of Buffon. I aid not long wait for
an anfwer^ which, as the author defired me to
publifliit, I ihall tranfcribe ia this place.

Genthod near Geneva.

Nov. 29, 17
^* cxvii. I was not acquainted with Dr.
Pirri's book. The fhort account you give
Hie of it furprizes me exceedingly. Is it
potlible that the eighteenth century could
have produced a writer capable of aiferting,
that the tadpole and frog are two eflentially
different animals ? Can this writer ever have
read Swammerdam ? x\nd yet how can he
treat of frogs without reading, or at leaft
occafionally confulting him ? Was not your
illuftrious countryman Vallifneri, whom he
muft doubtlefs have iccn, fufficient to fhew
him the falfehood of his opinion ? To me,
this ftrange aflertion of Dr. Pirri appears al-
together incom.prehenfible. It is probable,
that fome fecret intereft has led him into this

miftake.

I3S DISSERTATION I.

miftake. An opinion fo fmgular, does not
deferve to be very anxioufly confuted. Every
naturalift will excufe you from taking much,
pains for that purpofe.

*' You inform me that Dr. Pirri declares,
that my reflediions on organized bodies have
not perfuaded him of the pre-exiftence of
germs. 1 am not furprized that a naturalift,
who believes the tadpole and frog to be two
diftiad; animals, fhould not be fatisfied with
my proofs, I fhould be much aftoniihed if
he were.

Your partizan of Epigenefis will furprize
thofe who have not fufficiently reflected on
the influence of opinion. He owns on the
one hand that you have fully proved the orga-
nic molecules of BuiFon to be true animal-
cules, yet on the other he maintains that fuch
molecules exift, though they are inviiible. If
they are not perceptible^ how does he know
that they exift ; you tell me that he deduces
this conclufion from confequences. I ought
to be made acquainted with thefe confe-
quences if I am to judge of their force. But
the reafoning of this author does not incline
me to think favourably of his ikill in logic,

A miftake in reafoning may indeed eafily be
forgiven, but v/ant of accuracy and fidelity in
quoting authors, is not fo readily to be ex-

cufed.

DISSERTATION !• 1 39

cufed. He attacks the involution of bodies,
by mutilating a palTage of my Corps orgariifes-,
he m.ight doubt of his caufe from this alone,
if he could form a proper judgment of his
own condudt. I well know the argum^ents,
fays he, ufually adduced in proof of the pof-
fible tenuity of matter ; nor am I unacquainted
with the geometrical demonftration of its in-
linite divifibility. But I alfo know that thefe
are mere illuiions, to lurprizc the imagina-
tion, and cloud the reafon, as Mr. Bonnet has
ingeneuouily confeffed. Art. cxxvii. of his
Corps organijh^ where he thus expreffes him-
felf concerning involution. '^ The infinite
divifibility of matter by which involution, or
the hypothefis, which fuppofes one germ to
be contained within another is fupported, is
a mathematical truth and phyfical falfehood.
Every body is necefl^afily finite ; all its parts
are of neceflity fixed and determined." —
Who would not conclude from this extract,
that I was combating the doctrine of involu-
tion ? Yet this is the very pafiTage in which I
endeavour to prove its pofiibility.

Dr. Pirri, in order to perfuade his readers
that I concur with him in opinion, dexte-
roufly feparates four lines from the paragraph,
fiapprefiTes all the refi:, and then praifes my
ingenuoufnefs : I am forry I cannot return

the

140 DISSERTATION I,

tlie compliment, but the truth is, that he
makes me aflert jufl the contrary of what I
was endeavouring to prove : My words are,
" the hypothelis of involution is npt without
probability, but it is not necellary to fuppofe
an endlefs involution, which would be an ab-
furditys the infinite divifibility of matter,
which might furniih ground for maintain-
ing fuch an opinion, is a mathematical truth,
and a phyfical falfehoodj every body is ne-
ceffarily finite, all its parts are fixed and de-
termined." I then proceed thus, *^ we are
utterly ignorant of the fartheft divifion of
which matter is capable; and' this ought to
prevent us from confidering the involution of
germs as impoflible. We need only open our
eyes and look round us, in order to learn that
matter has been prodigiouily divided. The
fcale of corporeal beings is the fcale of this
divifion. How many times is a mucor con-
tained in the cedar, the mite in the elephant,
the aquatic flea in the whale, a grain of fand
in the terraqueous globe, and a globule of
licrht in the fun? An ounce of gold can be
drawn by human art into a v/ire, eighty or
one hundred leagues in length. The micro-
fcope iliews us animals, of which feveral thou-
fands do not equal the fmalleft grain of dufi:.
An hundred fuch obfervations might be men-
tioned.

DISSERTATION U I4I

tinned, and fliall we, without hcfitation, pro-
nounce the theory of invokition to be ablurd ?

In the cccxLiid paragraph 1 treat pro-
feffedly on involution, and tranfcribe a long
paljkge from Bourguet, in order to deftroy
the force of thofe calculations by which the
celebrated Hartfoeker affedled to overwhelm
the imagination. How then could Dr. Pirri
fail to perceive, that fo palpable a deviation
from good faith would difcredit his book ?

I am yet more aflonifhed at another palTage,
in which this author has the aiTurance to af-
fert, that ^' according to Mr. Bonnet's own
confeffion, the involution of bodies is a fyftem
founded on equivocal fadls, and on obferva-
tions that do not directly lead to any fuch con-
elufion." An aflertion fo pointed, and at the
fame time fo falfe, can impofe on thofe only
who have never read me ; for who among my
readers does not know that I have ever re-
garded the evolution of organized bodies, as
eftabliHied upon the mofl unequivocal facts,
and the mofl conclufive obfervations ? All my
works are full of the dodrine of the evolu-
tion of organized bodies ; no author has faid
more concerning it, or endeavoured to con-
firm it by ftronger proofs. It feems morally
impofiible, that Dr. Pirri could have con-
tinued in his miflake a fihgle moment in a

matter

142 DISSERTATION I.

matter fo evident; and therefore fiace he puts
into my mouth a propofition, which he
knows to be repugnant to my way of think-
ing on this fubjed:, I may fafely conclude,
that his book was not di(ftated by the pure
and difpaffionate love of truth. But I have
beftowed too much attention on an author fo
fegardlefs of public efteem, as toexpofe him-
felf voluntarily to the heavy charges of fup-
preffion and bad faith. I think you fhouTd
but juft mention his work, for if you confute
him at length, you will confer upon him a
degree of celebrity, to which he is by no
means in titled.''

End of Dissertation I.

A DIS-

A

DISSERTATION

CONCERN,ING THE

ARTIFICIAL FECUNDATION OF
CERTAIN ANIMALS.

CHAP. I.

ARTIFICIAL FECUNDATION OF THE TER-
RESTRIAL TOAD W,ITH RED EYES AND
DORSAL TUBERCLES.

CXVIII. "pHE firft attempt to efFed; ar-
^ tificial fecundation was made
by my immortal countryman, Malpighii
having taken the eggs out of the ovaria of the
moth produced from the filk-worm, he
moillened them vvith the feminal liquor of the
male. The event did not indeed correfpond
to the wiflies of the curious naturalift, for the
eggs proved barren. The learned Bibiena,
formerly profeffor at Bologila, was in Hke
manner difappointed when he repeated and
varied the experiments of his illuftrious fel-
low-citizen [a). Such a projed:, however,
'tiiough it fail in moths, does not feem un-

(a) ■ AOl. Acad. Bon. T. 5 . Part I.

likely

144 DISSERTATION II.

likely to fucceed in thofe animals in which
fecundation takes place without the body of
the female, as in frogs and toads. Hence
my celebrated friend Mr. Bonnet, ever fmce
I communicated to him in 1767, my difcovery
of the pre-exiftence of the germ in the frogs,
has been conflantly urging me to attempt the
artificial fecundation of this animal. And as
I conceived that if this experiment fhould
fucceed, it would throw new light upon the
natural hiftory of animals, and more efpecially
upon generation, I refolved to undertake it.
When I pub]i(hed my Profpedus in 1768, I
gave an intimation of my defign. Other oc-
cupations, however, prevented me from car-
rying it into execution till the fpring of 1777,
and the prefent year (1780) in the courfe of
which I enjoyed more leifure. The animals
mentioned in the five firft chapters of the pre-
ceding differ tation, were the fubjedls of my
experiments.

cxix. I began with the terreftrial toad with
red eyes and dorfal tubercles, v/hich begins
earlieft in the fpririg to propagate its fpecies.
I have already obferved, that the female, with
the male on her back, difcharges flowly at the
anus tv/o fhining vifcid cords, full of black
globules. Thefe globules are minute tad-
poles, which the male fecundates at the time

of

DISSERTATION 31. 145

of expuliion, by befprinkling them with fe-
men (xLv, xlix, l, li, lvii). As there-
fore the tadpoles are at this period beft dif-
pofed for fecundation, I tried to effedl it in
the following manner. Juft before parturi-
tion, of which I was apprized by the excef-
five fwelling of the belly, I parted the male
from the female, and fet the latter byherfelf,
in a veiTel full of water. In a few hours the
two cords began to appear; as foon as about
the length of a foot was excluded, I cut them
off, and left one in the veffel, while I took
out the other, in order to wet it with femen,
which I procured from the male that had been
juft feparated from the female. It is eafy for
any one who has the flighteft fkill in compa-
rative anatomy, to find the feminal veficles.
In this animal, they lie below the tefticles,
and cover part of the kidneys. At the time
of coupling, they are always full. I laid
open the veficles, and receiving the Kquor
which had the tranfparency of water, into a
watch-glafs, I fpread it on the piece of cord
with a pencil; but the quantity was only fuf-
ficient to go over two-thirds; after the ope-
ration, I placed this piece in a vefTel of the
fame water as that in which the unimpreg-
nated portion lay. This experiment was
made on the i6th of March; as the weather
Vol. IL L was

1^6 DISSERTATION IJ.

was rather cold, and confequently unfavour-
able to the evolution of the tadpoles, I was
forced to wait the* longer in fufpenfe for the
cvqpA, about which 1 was not a little anxious.
I examined the cords v/ith the clofeft atten-
tion feveral times a day, without perceiving
the fmalleft difference for the iirll: five days.
In both the mucus was equally enlarged, as
well as the tadpoles : and they retained their
globular ihape. It was not till the fixth day
that I began to conceive hopes, that the ap-
plication of the feminal liquor had not been
ineiFedual. Many of the tadpoles compre-
hended in the two-thirds of the cord, over
which the pencil had paiTed, began to affume
an elongated figure, while the others prefer-
ved their round form, as did alfo thofe of the
piece of cord left in the other vefiel. The
feventh day was ftill more favourable to my
hopes ; for together with a manifeft elonga-
tion, an increafe in bulk became vifible ; thefe
appearances grew more evident every day, in-
fomuch that there no longer remained any
doubt of a confiderable evolution of the tad-
poles. On the eleventh day, I perceived
them movinp- withLn the amnion, and on the

o

thirteenth they quitted the membranes, and
fwam about the v/ater. On the other hand,
the unim,pregnated tadpoles b^gan to corrupt,
. and

DISSERTATION II. I47

and in time they were quite decompofed, and
turned putrid. When I had thus called into
life a number of animals, by imitating the
means employed by nature, the reader will
conceive the fatisfadtion I received from the
iuccefs of an experiment fo precarious and un-
certain. He will eafily imagine, that I was
not difpofed to ftop at my firlt difcovery, but
that I determined to repeat and vary m.y trials,
in order to deduce fuch confequences as mi^-ht
illuilrate the fubjed:.

cxx. All the tadpoles in the portion of
^cord that Vv^as wetted with femen, w^ere not
evolved. They were in all a hundred and
feventy-fix, of ^vhich fixty- three fpoiled.
This probably arofe from, their not having
been touched by the fecundating fluid. I
now determined to repeat the experiment
upon another piece of cord, wdiich a female
juft feparated from^ the male, w^as about to
difcharge. As this piece was only five inches
long, I could bathe it completely with the
feed of two males. I may here remark, that
if we wifh to find the veficles full, Vv'e muft
open them at the time of copulation . The lar-
geft quantity of feminal liquor afforded by a
iingle male, is generally two grains, though it
fometlmes amounts to almoU three. When
the males are no't mounted upon the females,

L 2 there

148 DISSERTATION II.

there is either no fluid at all in thefe refer-
voirs, or only a very inconfiderable quantity:
they are indeed fo much fhrunk, that there
is fome difficulty in finding them. But to
return to myfubjedj I found that a greater
quantity of femen caufed more tadpoles to be
evolved. The feafon being now a little fur-
ther advanced than at the time of my firft ex-
periment (cxviii), the tadpoles began on the
fifth day to take on an elongated fhape, on the
tenth they ihewed manifeft tokens of anima-
tion, and on the eleventh were fwimming about
the water. They were in all an hundred and fe-
ven, out of which number eight only failed;
whether it was becaufe they had not been im-
pregnated, or more probably becaufe they were
vitiated. In the natural procefs, among a great
number of tadpoles, a few always fpoil.

cxxi. In thefe two fuccefsful experiments
(cxix, cxx), the cords had been difcharged
by the female into water. Natural fecunda:-
tion always takes place in this element. But
I had learned from obfervation, that it fuc-
ceeds juft as well when the animals are re-
moved to a dry place. It was thus, that I
v/as fortunate enough to difcover the natural
mode of impregnation (xlvii, xlviii, xlix).
I therefore fuppofed, that artificial fecunda-
tion would fucceed in the fame circumftances ;

a long

BISSERTATION II. I49

a long portion of cord difcharged in a dry vef-
fel was moiflened with feminal fluid, and then
put into water, along with another piece
brought forth by the fame female, but not
impregnated. In twelve days the tadpoles of
the latter were half putrid, while thofe of the
former were evolved, and fwimming about
the water. While employed about thefe ex-
periments, I was careful to obferve whether
artificial fecundation is flower in its eifecfts
than natural. Having two toads coupled, I
waited till the female had difcharged part of
the cords, and the male had befprinkled it
with femen, I then removed the male, and
cutting off the cords, clofe to the anus, left
them in the water. As foon as the female
l;ad difcharged another portion of cord,
(which happened in a quarter of an hour) I
cut it off, and impregnated it with the femen
remaining in the veficles of the male^ and
this piece was put into the fame yeffel with
th^t which had been naturally fecundated,
that it rnight be feen which would foonefl;
produce pomplete tadpoles. But evolution
and animation kept an equal pace in both, an
obfervation w^hich I afterwards faw confii|:ipLe4
both with refpecfl to toads and frogs.

cxxii. My attempts to produce fecun-^
^a,tion by artificial means, have hitherto been

L 3 made^

1 50 DISSERTATION" IT.

made, only when the tadpoles had arrived at
the place deftined by nature for impregnation
and evolution. But fuppofe it v/as attempted
within, the body. We know that they are
at jfirft lodged in the ovaria, then pafs along
the oviducfls, and at laft get into the uterus.
Will artificial fecundation fucceed alike in
thefe three receptacles ? Thefe refledtions fti-
mulated my curiofity, and I believe I have
now data fufEcient for the folution of the
problem. I began with the uterus. This or-
gan is divided by a mem^branous partition into
two cells, v/bich arc quite filled with tadpoles,
as foon as they have pa fled through the ovi-
ducts. They are inclofed in the glutinous
cords, which are very much entangled; it is
not, however, difficult to draw them entire-
out of the uterus with a forceps, if they are
managed gently. I opened the abdomen of
feveral coupled females when the cords began
to be excluded, for at this time the uterus is
ahvays full, and difentangling part of the
mafs which lies in this vifcus, I bathed it
with feed, and fet it in a veflel of water. The,
reft of the cords was put at the fame time into
another veiTel of water ; but not one tadpole
contained on the latter portion was evolved,
whereas all tliofe which had been impregnated
became complete tadpoles. It is therefore

to

DISSERTATION 11. Ifl

to be inferred that thefe germs, by the time
tliey get into the uterus, are arrived at fuch
a ftate of maturity, as renders them capable
of being fecundated.

While I was engaged in thefe experiments,
I was eye-witnefs of an accident that deferves
to be mentioned. Having often obferved the
feminal liquor of the toad, I found it very full
of fpermatic worms, which, like thofe of the
frog, have an oblong Ihape, and writhe their
body as they move. Upon two occjifions I
have been greatly furprized at finding this fluid
totally dellitute of fuch inhabitants. I was
induced to try, v/hether it is alfo deftitute of
fecundating virtue, but I found that it was
juft as eftedtual in this refpeft, as that which
iBoft abounds with thefe diminutive animals.

cxxiii. I next proceeded to try whether I
could impregnate thofe germs, which in
couoled females are often to be found in the
ovidudls. I fucceeded upon many of the
larp-eft, thofe which lie neareft the uterus, but
thofe which- were fituated in the narrow part,
in the vicinity of the heart, v/here the other
extremity of the oviducts is placed, all baf-
fled my attempts. Thefe different refults may
perhaps be thus explained. The gluten iii
which the tadpoles are imbedded, and Vv^hich
fprnas the two long cords, is produced as the

L 4 germs

152 r> S I S E R T A T I O N IT."

germs pafs through the oviduds, for they
are totally deilitut6 of it before they enter
into thefe canals. Thofe tadpoles therefore
v/hich have paiTed along the greater part of
the ovidu6ls, and of courfe are neareft to the
uterus, will be furrounded by moft gluten.
This fubflance has been appointed by nature
for the firft nourifliment of the fetufes. If
therefore they happen to be provided with a
fufficient fupply, as thofe are which lie near-r
eft to the uterus, the afperfion of feed will
not be ineffedual ; but the contrary will hap-
pen with refped; to thofe which have little
or no gluten; for fhould they be animated by
the ad of fecundation^ they will foon perifli
from want of nourifliment. The neceffity of
gluten during the firft period of evolution, is
evident from another experiment, in which the
tadpoles having been entirely ftripped of it,
v/ere wetted v^ith femen, but they came to no-
thing ^ nay, very few of thofe were evolved
from which part only was taken. Upon open-
ing one day a female during copulation, I
found the tadpoles in the abdomen, inftead of
the uterus and oviduds. Their colour was
black, as it is when they are arrived at a ftate
of maturity, but they were without gluten,
having never entered the oviduds. Thefe
fetufes, after beins: moiftened with ferninal

licjuor

DISSERTATION II.' 15^

liquor were not evolved, as the reader will
naturally fuppofe.

cxxiv. For the fame reafon thofe takeix
from the ovarium would not grow. This
vifcus is divided into two large lobes, each of
which confifts of fmaller lobes. All are full
of Httle tadpoles, till the feafon of amours ar-
rives, when they feparate from their ftalks, in
order to go whither nature has deftined them.
1 befprinkled many of thofe tadpoles with
feed when they were about to quit the ova-
rium, hut in vain. This experiment fug-
gefted a curious idea. I had found that the
abdomen of female toads, and this is alio
true of frogs, may be opened, not only with-
out immediately deftroying them, but fre-
quently without preventing them from bring-
ing forth their young, which alfo are after-
wards evolved, either inconfequence of natu-
ral or artificial fecundation. It is only ne-
ceffary, that the female thus maltreated fhould
be kept in the dry; otherwife the water will
enter in at the wound, and occafion death be-
fore parturition takes place. Now what will
happen, thought I, if the abdomen of a fe-
male Ihould be opened, and the feminal fluid
be fpread upon the ovarium ? May it be ex-
pected that the tadpoles, after quitting this
vifcus, paffing through the oviducfts and ute-
rus^

154 DISSERTATION 11.

rus^ and being diicharged at the anus, will

grow? Thougk I had little exj3ed:ation from
the experiment, I was determined to per-
form it. Having with this view perforated
the abdomen of two females, I threvv^ a drop
of feed upon each ovarium from a fy ringe in-
troduced through the w^ound. I m^oreover
ni.ade a perforation in the m^embrane that in-
veils the ovarium, and injed:ed another drop
of feed, which muft have come into immer-
diate contact with the tadpoles. One of the
toads died five hours after the operation with
the tadpoles in the ovarium, but the other
difcharged part of them at the anus imbedded
in gluten, as if llie had been in a flate of the
moil perfect health. I kept them very care-
fully in water, but not one came to perfec-
tion ; whence I was obliged to infer, that the
gluten is fo indifpenfibly neceiTary for the
nutrition of thefedelicate beings, that ihould
it not be prefent at the tinic of afperfion with
feed, they will periih, even though it ihould
be, aftenvards fapplied..

cxxv; Having eftabliihed upon a number
of deciiive trials^ the pofEhility of artificial
fecundation with femen (cxix, cxx, cxxi,
cxxii, cxxiii), I thought of trying whe-
ther the expreiled juice of the tefticles would
anfwer the fame end, I fuppoied this not

iinlikely.

DISSERTATION II.

00

unlikely, the tefticles being the organs in
which the feed is formed, or rather perfec-
ted and rendered fit for fecundation; but on
account of their fmall fize in this animal, 1
could not hope to obtain it pure : and my
only refource was therefore to fqueeze out the
juice, and ufe this for my experiments. The
tefticles in the prefent fpecies of toad are fi-
tuatedatthe upper part of the kidneys; they,
have a yellowiih colour and an oval flaape,
but are a little gibbous on one fide, like thofe
of the cock. At the feafon of generation
they contain a brown, denfe, and fomewhat
vifcid liquor. Having collected a little of this
liquor in a watch-glafs, I moiftened with it
»about an hundred tadpoles, part taken out of
the uterus, and part difcharged by the female,
after the male had been removed. I fucceeded
perfedlly; the tadpoles grev/, and I frequently
repeated the experiment with equal fuccefs.
Upon m.aking a comparifon between the ef-
ficacy of the feed, and the juice of the tefticles,
I found that both fluids produce their efiecls
in the fame time ; but the latter did not caufe
the evolution of fo o-reat a numiber as the for-
mer, thous;h I did not then know whether this
arofe from its inferior ad:ivitv, or ratiier from
its denfity, a quality that prevents its diffuiion
over an equal extent of furface.

cxxvr.

1^6 DISSERTATION IT.

cxxvi. In May 1780, while I was com-
poiing the prefent chapter, the fiihermen
brought me a fpecies of toad, concerning the
generation of which I have faid nothing in
the preceding differtation, for I was totally
unacquainted with it 3 I fliall here give a ihort
defcription of it, as it relates to the prefent
fubject. This fpecies is fmaller than the fe-
tid terreflrial toad, but is of the fame colour,
if we except the belly, which is of a brighter
white.. But the diverfity of manners and or-
ganization fhews, that the two fpecies are to-
tally different. The fkin upon the back of the
fetid toad is rough like fliagreen, the body is
rather long, and the animal, like frogs, moves
by taking long leaps. The other has a fmooth
ikin, a thick fliort body, and jumps a very
little way. The male of the former fpecies
utters a found refembling a m^n's whiftle.
The croaking of the latter is very low and in-
diftind, a clear proof that the organs of the
voice are very differently conilruded, The
ftrufture of the parts of generation alfp dif-
fers ; the female of the fetid toad brings forth
two cords, but that of the other only one;
the former derives its name from its bad
fmell, but the odour of the latter is at moft
not more oifenfive than that of garlic. The
male of the fetid toad throws his arms round

the

DISSERTATION II. I57

the thorax of the female, but that of the new
fpecies clafps the abdomen. Hence it is ap-
parent, that this toad ought not to be con-
founded cither with that with which I have
been contrafting it, nor with the Bufo ignem
of Roefel, in which the lower part of the body
is ornamented with flame - coloured foots
(ccccLxiv); for in the fpecies in queilion,.
not a veftige of fuch fpots is to be perceived-

The iirfl that fell into my hands was coup-
led, and the female was difcharging her cords.
I had here an opportunity of admiring the cu-
rious fpedtacle defcribed by Dem.ours (cii).
When they were placed upon my hand, they
feemed at firft a little timid, but foon after-
wards the female continued her difcharge,
though I did not obferve that the male ufed
his hind legs to extradl the cord. I faw, how-
ever, what he did not obferve, I mean, that
the male fprinkled the tadpoles from time ts^
time with femen emitted from the anus,
which in this fpecies is terminated by a point,
I watched this phenomenon for about thir-
teen minutes, and then refolved to open both
the male and female, for the lake of the fol-
lowing experiments. Having extra dted the
remainder of the cord, which meafured about
a yard and a half, I divided it into four por-
tions; One was.Jeft untouched, the io^Qoni,

was

155 DISSERtAtlON li.

was molftened with the feed remaining in the
veiicles of the malej the third with juice ex-
prelled from the tefticles ; and the laft with
two drops of the feed with which the male
was impregnating the cord as it was excluded,
which I had intercepted in a watch-glafs.
Thefe four pieces were fet in feparate vefTels
of water, and in a fifth was placed that piece
of cord which had been already fecundated.
The refult was what I imagined it would be,
from former obfervations. Except the un-
touched piece of cord, all the reft were ani-
mated v/ith a number of tadpoles ; whence
we may draw two inferences, firft, that in- this
frefh fpecies fecundation is alfo external ; and
fecondly, that it may be eiFed:ed by art,
either by means of the feminal fluid, or the
juice of the tefticles. Four other couples
, were afterwards brought to me, two of which
ferved to confirm the foregoing obfervations,
and the two others for experiments, which I
fhall relate in another place.

cxxvii. lihall fixniih the prefent chapter,
with a fhort digreilion concerning the mode
of propagation in this new fpecies. The
cord, both in the ovidudls and uterus, is full
of black globules, v/hich whether examined
internally or externally, exhibit characters
perfectly refembling thofe of the tadpoles of

other

DISSERTATION II. I59

Other fpecies, when they He in the ovidudls
or uterus. If the impregnated globules be
compared v/ith the unimpregnated, they will
likewife be found to bear an exa6l refemblance
both internal and external. But in time the
latter become white, the furface grows wrink-
led, and chopped in various places ^ the wa-
ter diilblves them, and they at laft fall to
pieces, and are quite decompofed. The ap-
pearance of the fecundated globules change^
alfo in about a day, but in a manner totally
different- Upon the furface may be perceived
tv/o furrows, which meet to form an angle „
Above the angle a prominent filament is feen,
and at the fame time the globule increafes in
bulk and length, w^hile the end grows finer.
During the following hours, the furrows be-
come deeper, the filament projecfts further,
and the point growls longer; on each fide of
the furrows arif^ two fmall tumours, v/hich
before were not vifible. In about a day longer,
the myftery concealed under thefe parts,
which are gradually unfolded, is laid open.
We find that the two furrows are the m^arks
of the mouth, that the prominent filament is
the fpine, that the pointed end is the tail, and
the two tumours the gills. All thefe parts
become more diftindi:, when the young ani-
mals begin to move about tlie water. It ap-
pears

l60 l>lSSEfttAtiON St.

pears therefore, from thefe obfervations, that
the fame law which prefides over the birth
and evolution of the fpecies mentioned in the
preceding dilTertation, extends likewife to
this, that the fetus belongs to the female, and
that the afperfion of the feed of the male is a
condition necefTary to the animation and evo-
lution of the fetus.

CHAP.

D I

9SERTATI0N IK l6l

CHAP. II.

ARTIFICIAL FECUNDATION OF THE WA-
TER-NEWT, AND THE FETII^ TERRES-
TRIAL TOAD.

CXXVIIL A S the fecundation of the wa-
"^ ter-newt does not take place
without the body (clxxx, clxxxi, clxxxiv),
as in frogs and toads, I could not try to im-
pregnate the fetufes, after they have been dif-
charged by the female, but was obliged to
feek fome other means of accom^plilhing my
intention. The female nevv^t has no uterus;
hence the fetufes, after quitting the ovarium,
pafs along the oviducts into the re(fLum, and
are difcharged at the vent. The feed of the
male infinuates itfelf into this aperture, and
fecundates the fetufes that lie nearefl to it.
I have moreover ihewn in the eighty-fourth
paragraph, that the more remote fetufes, thofe
which are fituated higher in the oviduds, are
not then impregnated; and that before this
can happen to them, they muft come down
lower, and take the place of thofe which have
been impregnated and difcharged. Thofe
Vol. IL M there-

t6z dissertation rr,

therefore which occupy the ovidufts, appeared
to be the proper fubjedls of my e:xperiments ;;
but my attempts to fecundate them did not
fucceed. I proceeded in this manner; having,
laid open the oviducts of a female, and the
vafa ieferentia of a male^, I took out the feedy
which in whitenefs refembles milk, and moi-
ftened the fetufes lying high in the duds ; I
then put them in water without delay. Like
tjiofe which are brought forth naturally, they
jTunk to the bottom,, where they were held by
the tenacious gluten tliat invefts them, but not
one grew. The gluten gradually quitted
them, they burft, and were diflolved. I
ihall not relate the many frequent repetitions^
and variations of this experiment, how I al-
tered the dofe of feed,, fometimes letting fall a
few drops upon the fetufes, fometimes bath-
ing them fparingly,. and at others immerfing
them in it, and as it were faturating them^
but ftilltono purpofe. Their fituation in the
oviducts made me apprehend,, that they pe-
riflied for want of a fufficient quantity of
gluten, as is the cafe with tadpoles taken out
of the upper part of the ovidud: (cxxiii),
and at the fa:me time fearing on the other
band, left, if I took them from a lower fitua-
tion, they ihould be impregnated by the male*
I bad recourfe to an expedient which I thought
- . . - would

DISSERTATION II. 1 63

would determine whether my apprehenfions
were jull. I was then (it was in April) in
polTeffion of feven female falamanders, which
I had kept all the winter in water^, apart from
any males ; notwithflanding this, they were
beginning to difcharge their fetufes. I
thought, therefore, of trying to fecundate
thefe fetufes, being certain that on the one
hand thev were inverted with a fufficicnt
quantity of gluten, and that on the other
they had not been impregnated. I have be-
fore remarked, that the males during the fea-
fon of their amours, will emit their feed, if
the belly be gently preffed, as alfo the fe-
males their young (lxxx, lxxxiv). By this
eafy method, 1 got thefe femiale newts to
bring forth their young, and as they came
away, took care to mioiften them with feed.
But notwithftanding this expedient, I never
faw one of them grow, though I carefully
kept them in water,

cxxix. Mortified at fo many difappoint-
ments, I was about to relinquiili the attempt,
under a perfualion that artificial fecundation
w^ould not fucceed on newts, w'hen a doubt
fuggefted itfelf, whether I had not negledted
a precaution eflential to the fuccefs of thefe
experiments. In another place I have re-
marked, that the male fecundates the female,

M 2 not

164 DlSSERTATlOi<r It,

not by injecting his feed immediately into ber^
but by throwing it into the water, whence h
paiies into the vent of the female, and im-
pregnates all the fetufes that lie near the
redium (lxxx, lxxxi)- It is therefore evi-
dent that the feed, when it produces its effect,
is not pure, but diluted in water. Hence I
was led to fufpedl that pure feed, which I had
iifed in my experiments^ was not fit for fe-
cundation, (perhaps on account of its too
great denfity) but that it mtiil be diluted in
water: I tried this method, and obtained re-
fults very different from thofe which have been
jufl related. By gentle preffure upon the bel-
lies of the fcYcn females (cxxviii) that had
htcn kept by themfelves^ I procured the dif-
charge of twenty-feven fetufes. I bathed
them all with water in which a fmall por-
tion of £ccd had been diifufed. Seventeen
periilied, the remaining ten did well, and
during their evolution prefented the appear-
ances that are confequent upon natural fecun-
dation (lxxxvii, lxxxviii, lxxxix). By
imitatine Nature therefore in this circum-
ftance, I fucceeded in fecundating this am-
phibious animal by art, as well on the pre-
fent as on other occalions; I loft indeed many
fetufes, but this could not furprize me, fincc

many

DISSERTATION II. 165

many perilTi alio after the natural impregna-
tion (lxxxix).

The juice expreiied out of the teflicles di-
luted in water, anfwers the purpofe of fecun-
dation, though in this cafe too, about one-
third only of the fetufes is evolved. This
failure, induced me to defiil from the profecu-
tion of my experiments on this animal for
the present. The fetid terreftrial toad next
.engaged my attention, and indeed iuUy an-
'fwered my expectation.

cxxx. W:e have feen, that in the terref-
trial toad with red eyes and dorfal tubercles,
artificial fecundation fucceeds not only on the
tadpoles that have been difcharged, but alfo
in thofe which lie in the uterus, and at the
inferior extremity pf the oyiduds. V/e have
moreover ktn, that it may be elFeded either
by the feed, or the juice of the tefticles. I
can aiTure the reader^ that the refult of thefe
jexperiments repeated on the fetid toad, was
iexadtly the fame.

But the great quantity of |:his fpecies with
which the fifhermen fupplied me^ the abun-
dance of tadpoles contained in the uterus, and
the facility with which they may be fecun-
dated, led me to attempt fomething befide.s
the bare confirmation of my preceding ob-
lejyations. The difcovery of the mpans of

M 3 calling

1 66 DISSERTATION H,

calling forth thefe animals into exiftence,
without the co-operation of the male, was
an experiment pregnant with many others,
which I was the more tempted to undertake,
fmce the harveft had not yet been touched by
the fickle of philofophy.

One of my principal views was, to afcer-
tain what would be the confequence of trying
to force Nature out of her ordinary path, ei-
ther by adulterating the feed, and the juice
o£ the tefticles, or by attempting to produce
changes in the tadpoles. Such an invefliga-
tion promifed to afford much inHrndiion.

In the preceding experiments, I had ufed
the feedj, and the juice of the tefticles, imme-
diately after it ¥/as taken from the male. The
animal was fixed on his back, by means of
nails driven through his hands and feet ; af-
ter opening the abdomen, I fought for the
fem.inal veficles, which, when the inteftines
are removed, appear behind the bladder, un-
der the iliape of two tumours 3 if the blad-
der be evacuated, a better view of the velicles
is obtained, at the fame time the tefticles
com.e into fight; in this fpecies, they are of
a livid brown colour, and lie upon the kid-
neys. After having made this difpofition, I
took, as my deiign led me, either the feed, or
the juice of the tefticles^ and bathed the tad-
poles.

DISSERTATION II. 167

poles, I now thought of trying thefe fluids
fome time after the death of the animal. In
another publication I have obferved, that
frogs, toads, and other animals very tenacious
of life, m.ay be inflantaneoufly killed by iniinu-
ating a iharp inftrument between two of the
cervical vertehrie, and deftroying a little of
the fpinal marrow. They fall inftantly into
convullions, and ceafe to live; an event that
does not follow either decapitation, or any
other treatment. Three hours after I had
killed a fetid toad in this manner, I opened
the abdomen, and fearched for the feminal
veficles, which were a little coUapfed, not
now containing fo much feed as when the
animal is alive and coupled. With this feed
I bathed fome tadpoles taken out of the
uterus, whence all that were ufed in the ex--
periments related in this chapter were taken.
The event fliewed, that the feed had not fuf-
fered by a continuance of three hours in the
dead body. The fame obfervation is applica-
ble to another toad which had been killed five
hours and a half; the feed indeed being in
very fmall quantity, could not be fpread over
many tadpoles. In the courfeof {even hours
after death, the veficles were fo much flirivel-
}ed, that I could fcarce get a droD of feed^
which however retained its efficacy.

M 4 cxxxi.

i6S

DISSERTATION II.

cxxxi. Two immediate confequences may
be deduced from thefe experiments ; it ap-
pears in the firft place, that after death the
quantity of feed in the feminal veiicks gra-
dually diminifhes till it quite difappears, agree-
ably to the laws of the animal oecpnomy ; and
in the fecond, that this fluid, notwithflanding
its wafte, Icfes nothing of its virtue, at leaft
in feyen hours. But does it retain its prolific
power any longer after the ceffation of life ?
iV5 dead toads would not, for the reafon al-
ready alligiied, enable me to folve this pro-
blem, there remained no other expedient than
to take the feed out of the veficles, and keep
it in a phial or tube. Having procured all
that thefe toads would furnilh, I put it in a
little glafs tube, and ufed it at different times.
Six hours did not impair its efficacy, but after
the feventh hour it feemed to be weaker, for
only two- thirds of the tadpoles touched wdth
it came to perfection. The eighth hour pro-
duced worfe effects, and the ninth proved fo
hurtful, that out of fixty-five tadpoles, not
one was evolved. The reader is not, how-
ever, to fuppofe, that thi3 is always the exad:
meafure of the time in which the feed be-
comes effete. By many experiments I have
been taught, that this depends on the tempe-
rature of the atmofphere. In hot weather,

feed

DISSERTATION II.

66

feed taken out of its natural receptacles, be-
comes infix hours and a half unfit for fecun-
dation. But in a cold feafon, it retained
fomewhat of its virtue eleven hours and up-
wards. The frequent alternations of heat
and cold during laft May, (1780) afforded me
many opportunities of obferving thefe diffe-
rent phenomena. Finding that cold favours
the retention of the fecundating virtue, I
thought of carrying the experiment further,
by placing fome feed in an ice-houfe. It
nov^ retained its efficacy twenty-five hours.
When I reflect upon the nature of this liquor,
it does not feem difficult to account for the
eifeft of heat and cold. The feminal fluid,
like other animal fubftances, is fubje^l to pu-
trefaction; now putrefadtion is promoted by
heat, and retarded by cold. In my fecond
Ejfay concernhig the natural Hijlory of Anhnah
and Vegetables^ I have fpoken at large on the
tendency of extravafated feed to become pu-
trid, whence it lofes the fpermatic worms,
its natural inhabitants, and acquires others
of a very different kind, refembling the ani-
malcules of infufions. The feed of toads runs
fooner or later into the putrefactive fermen-
tation, and on this account probably becomes
effete, fooner when the atmofphere is warm,
than when it is cold.

I have

170 DISSERTATION U.

I have laid before, that in hot weather the
feed in fix hours and a half is rendered unfit
for its natural ufe. I found that in this cafe,
the thermometer ftands iSf- [a) deg. above
the freezing point. This fuggefted to me
the idea of trying what would happen to this
fluid, if it fhould be kept for a iliort time in a
higher temperature. From feveral trials it ap-
peared, that the heat of 30 (^), and even 32
{b) deg, was not prejudicial, when the feed
is fiibjecfted to it for two minutes only; but
at the 35th {b) deg. it was quite fpoiled.

cxxxii. But it is time to turn the reader's
attention to the experiments on the juice of
the teflicles, the fecond head of the firft en-
quiry propofed in the cxxxth paragraph ; as
. before, I left the tefticles in the dead animal ;
bat the event was very different. In the ve-
iicles the quantity of feed was io much dimi-.
nilbed, that in feven hours there fcarce re-
mained enough for one experiment. The
tefticles on the other hand of the fame indi-
vidual preferved their juice fufficiently, and it
was fit for fecundation. But that v/hich was
exprelTed from the tefticles of another male
left dead for a day, was in fufficient quantityi

{a) About 73 or 74 of Far. tliermometer. {b) ■^o;:;zggj,
;2 — 104, 35i::iio|, nearly of the fame fcale,

but

DISSERTATION II. I7I

but altogether effete. In the profecutlon of
this enquiry, I found, that the continuance
of the efficacy of this juice is connefted with
the temperature of the atmofphere, or, tofpeak
more properly, with the time in which it be-
gan to grov/ putrid, as happens with refped;
to feed alfo (cxxxi). Hence in warm wea-
ther, the tefticles afford nothing fit for im-
pregnation after nine or ten hours have elap-
fed; whereas v/hen kept in an ice-houfe,
theirjuiceis efficacious after thirty-four hours.
It appears, however, from a comparifon of
this with the preceding paragraph, that in the
fame temperature this juice retains its virtue
longer. Does this arife from its not becom-
ing putrid fo foon, at leafl when it remains
in the teflicles ? I incline to this opinion,
though I have not made any dircvfl experi-
ments with this view. •

cxxxiii. The teflicles of the toad are fo
fmall, that when expofed to the air, they be-
come fhrivelled and dry, fooner than they
putrify. In the mean time they do not lofe
their virtue, but the juice, as long as they
^retain any, is fit for fecundation.

As they dry, they grow hard, and afTume
the appearance of thin leather; when put
into water, they refume their former plump-
jicfs. When prefTed, they appear to be full

of

iy% DISSERTATION II.'

of juice, but it will not caufe the evolution of
germs. . And this is by no means matter of
furprize, lince the better and more adtive part
of it, muft evaporate during deficcation.

The fame effed: is produced by exceffive
heat, as when the tefticles are kept a few
minutes in air or water warmed, to about the
thirty-fifth degree. ,

If we combine the fads related in this an4
the foregoing paragraph, with thofe of the
cxxxth and cxxxift, it v/ill appear, that the
fan^e caufes are deftru6tive of the qualities of
the feed, and the juice of the tefticles. In-
deed it cannot be otherv/ife, fmce the latter
fluid confifts chiefly of the former; the fame
worms inhabit both. Hence it may be un-r
derftood how it came to pafs, that when I
bathed tadpoles with the juice taken from the
tefticles of toads long kept by themfelves, fe-
cundation did not take place ^ this was not
owing to a deficiency, but to the bad quality
of the juice. It was to no purpofe to try
the juice of the tefticles of young toads,
before they are proper for generation. The
failure arofe from the want of feminal fluid,
which, as is well known, is not produced
either in men or animals before a certain

age.

C XXX IV*

DISSERTATION II. 173

cxxxiv. In the artificial fecundation of
both thefe fpecies of toad, I had ufed feed or
juice of the tefticles not adultered with any
other fubftance. But having propofed in this
chapter to enquire into the confequences that
would follow the alteration of thefe liquors,
it became me after the trials already inflituted,
to mix various matters with them. The
flight difference between the feed and the
juice of the tefticles, rendered it probable, as
in fad; it happened, that their admixture
would not prevent fecundation. Water too,
though a fluid eflentially different, did not
feem likely to produce fuch an effecft, Cnce
the feed is emitted into water, and neceffa-
rily mixed with it ; and with refpect to the
newt, we have feen, that this is a requiiite
condition to impregnation (cxxix). In the
toad water heightened the prolific power of
the feed; but I content myfelf at prcfent with
giving a Ample intim.ation of this fad:, and
defer to the next chapter a particular account
of it, as well as of the important confequences
it affords. I here confine m^^felf to otiier li-
quors. In opening the fem.inal veficles, the
feed which when unmixed has the purity and
tranfparency of water, is always adulterated
with blood that iffues from the incifion made
in the abdomen : the mixture is then not un-
like

174 DISSERTATION lU '

like the wafliings of flefh; I have ufed it for
bathing a confiderable quantity of tadpoles^,
and have found it jufl as good as pure feed.
Further, blood, after being thus mixed, foon
coagulates, and if taken away, leaves the fe-
minal liquor as pure as ever. I have taken
up fome of the clots, and after rubbing the
tadpoles with it, have found that it animates
them, on account, no doubt, of the feed that
adheres to it. The fame remark may be ap-
plied to the other fluids of both male and fe-
male toads; the bile, the faliva,- the juices
expreifed from the liver, lungs and kidneys,
and in fhort the urine itfelf, do not prevent
the feed from producing its proper effed:, not-
withftanding the lail: is thought by many to
be poifonous, or at leaft corrofive and acri-
monious. Human urine is not prejudicial,
provided it is ufed in equal quantity. But
the number of tadpoles became lefs when the
portion of urine was increafed, infomuch
that when it was ufed in double quantity,
none were evolved. Vinegar agrees very
nearly with urine. Human faliva is innoxious
in v^hatever proportion it is employed. Here
I mav Doflibly be alked, whether a real in-
corporation of thefe feveral liquors with the
feed, took place : or rather, whether the feed
formed a feparate and diflindt body, as water

poured

DISSERTATION II. I75

poured into oil; in which cafe it would not
he furprizing, though fecundation fhould en-
fue ? I reply, with great confidence, that the
mixture took place in the firft of thefe ways,
and never in the fecond. When I dropped
thefe different liquors into the feed, 1 was
careful to ohfcrve what changes happened^
and that I might be better enabled to judge
I ufed the microfcope. The mixture feemed
always to be attended with a real incorpora-
tion of the two fluids. When water was
ufed, it appeared as limped and homogeneous
as if it had bee^u \vater alone* When the feed
v/as mixed wdth black vinegar, the mixture
had a blackilli colour, and w^hen with white
vinegar, it was fomewhat lefs opake. In
both cafes the acid loft fomewhat of its four-
nefs, a certain proof that the feminal fluids
which of itfelf is infipid, had been diffufed
through the whole of the vinegar. The fame
thing took place when urine was tried.

The juice of the tefticles aft^r being mixecJ
with the fame fluids, loft nothing of its ef-"
ficacy. And as it tinged thefc fluids with its
own colour, it was reafonable to infer that it
was incorporated w^ith th-^m as w^ell as- ths
feed. It appears therefore, that both thefe
prolific liquors preferve their qualities feme
time after the death of the animal, both when

pure.

lyS DISSERTATION II.

pure, and when by being mixed among other
matters they have fuftained a confiderable di-
vilion of their integrant parts. But I fhall
fpeak more particularly concerning fecunda-
tion after a great, nay, almofl infinite fepa-
ration of the particles.

cxxxv. I now come to defcribe the various
chano-es I have endeavoured to effect on tad-

o

poles before fecundation, which was the other
principal objedl of enquiry. Having killed
feveral females in the way defcribed in the
cxxxth paragraph, I left the tadpoles for
fome time in the uterus. I wifhed to know
how long after the death of the female, the
young are capable of being impregnated^
eight hours did not prove hurtful to them,
nor twelve ; but when bathed with feed, after
thirteen or fourteen hours had elapfed, the
diiFei-ence became evident, for out of about
tv/o h'^ndred, more than eighty perifhed.
To the tadpoles of three toads, fixteen hours
continuance in the uterus was fatal, but fe-
veral taken out of that of a fourth came to
perfedlion. This instance may ferve to con-
firm a maxim adopted by the moft able phi-
lofophers, according to whom a great mul-
tiplicity of trials is not merely expedient,
but neceffary, when we would eftabliih any
propofition. The induration of the tad-
poles

Dissertation ii, 177

J:>oles of the three firft toads, the thickening
of the mucus and its incipient putrefacflion,
were indications fufficient to make me ap-
prehenfive, left the application of feed fliould
not be attended with any effect. But I fup-
pofed, that in a lower degree of heat the tad-
poles might be kept longer, for thefe expe--
riments were made in June, when the ther-
mometer in the fhade flood at 20° — 22°'{a),
It readily occurred to me, that recourfe fhould
be had to an ice-houfe, in which I had before
kept the prolilic liquors good for a confider-
able time (cxxxi, cxxxii).

My fuppofition was confirmed by experi-
ments Tadpoles left in the uterus of two
females for forty-one hours in this degree of
cold, and afterwards moiftened with feed,
came mofl of them to perfection'. 1 cannot
inform the reader what ^&d: is produced by
immeriing tadpoles in various liquors, ^ not
having had time for making fuch experiments;
The only one which I could try was water ;
and I fhould not have imagined, that it would
be fo detrimental as it really proved to be,
confidering that the tadpoles are always depo-
fited and live in water. After tadpoles ex-
traveled from the uterus of a living toad, have

{a) 20=:;/, 22rz8i|.

Vol. IL • N been

I^S DISSERTATION II.'

been left four hours in water, the application
both of the feminal fluid and the juice of the
tefticles was quite ineffectual. They all turned
putrid in a few days. The fame event took
place on other occaiions, after the tadpoles
had lain for three, two, and even one hour
in water. This unexpedted phaenomenon
made me defirous of afcertaining the precife
time, during which tadpoles may be kept in
water without being rendered unfit for fecun-
dation. 1 found it to be exceedingly ihort,
about thirteen minutes ; many kept immerfed
longer, never came to perfedion, and after
a continuance of fifteen minutes not one v/as
evolved. This at leaft was what I obferved
concerning feveral hundreds.

But hovv^ does water fo foon damage, thefe
embryos ? It is quite contrary to what happens
when they are kept in the dry, whether they
are left in the uterus, or placed in a vciid ;
for it is certain, that a continuance of feveral
hours will not under this circumftance pre-
vent the effeds produced by fecundation.
The bed method of inveiligating the caufe
of the difference feemed to be, to obferve
carefully v/hat happens to the tadpoles, and
the mucus in which they are imbedded, while
they continue in water. It has been already
feveral times obferved, that the mucus and

tadpole s^

DISSERTATION 11. I79

tadpoles conftitiite two long cords, which
the female ilowly difcharges. The cords at
firft fall to the bottom, but if the weather
be warm they foon rife to the top, and con-
tinue to float. This afcenfion arifes from an
increafe of bulk, which renders the firings
fpecifically lighter than v/ater. The dilata-
tion is obvious to the fenfes, and if the dia-
meter be taken before they are put into water,
' apd after they have been immerfed fome time,
it will be found to be enlarged. This change
muft, I think, be imputed to water infmu-
atiag itfelf between the particles of the mu-
cus. And my opinion is confirmed by the
two foUow^ing reafons; the firings, when left
in the dry, do not increafe in bulk^ and if
thofe which have been immerfed be fqueezed,
v/ater will ooze out of them. FroiTi thefe ob-
fervations, I think we may account for the
hindrance water occafions to fecundation. It
is obvious, that the feed muil traverfe the
mucus, in order to reach and impregnate the
tadpoles. Now it muft either iniinuate it-
felf into the pores of that fubilance, or pafs
along certain dud:s provided on purpofe by
Nature, When thefe openings, of whatever
kind they may be, are free, as in the cafe when
the cords are kept in the dry, the paffage of
the feed through the m.ucus v/ill not be in-

N 2 terrupted^

l80 DISSERTATION IT,

terrupted; but fliould they be clofed, its in-
grefs will be prevented | this mud be the con-
fequence of immerfion in water, and thus we
come to underftand why in a few minutes
they are rendered incapable of being fecun-
dated.

cxxxvii. The infuperable obftacle arifing
from the inlinuation of water, has been
guarded againft by Nature, when fecundation
is left to the animals themfelves. The male
toad, as well as the male frog, ejedl their feed
upon the firings, when they have been only
a very fhort time in water. And I have
found, that the male always impregnates
thofe which have been juil: -brought forth,
and which confequently have been juft fub-
je6ted to the adlion of water. Thus as if
they could forefee that fecundation would not
take place after the tadpoles have lain fome
time in water, they never befprinkle fucli
with feed. I have put fomc females in water
by themfelves during the ad: of parturition,
and after about a yard has been excluded, have
admitted an equal number of males. The
males aflbmed their proper flation without
delay, and began to impregnate the tadpoles
lying clofe to the anus, without paying any
re;:pTd to the others. I faid above, as if they
could forejee ; for it is certain, that thefe ani-
mals

DISSERTATION II. l8l

mals have not fagacity to diflingulfli between
thofe that are fit, and thofe that are unfit for
impregnation. The mflin(fl allotted to them
by Nature, prompts them to mount upon the
female, and in this fituation to impregnate
the young. In fuch a pofture, they neither
do nor can impregnate any but thofe fituated
near the parts of generation ; and thus they
unwittingly fulfil the great purpofe of Na-
ture, the propagation of the fpecies. Hence
it is evident, that although fecundation is ex-
ternal both in toads and frogs, as it is com-
monly fuppofed to be in fiihes, it is not ef-
fected when the fetufes are feparated from the
female, and lie at the bottom of the water.
Of this truth, I have had the moft ample
proof in every fpecies of frog and toad men-
tioned in thefe two differtations 5 for when
many pieces of cord have been put in vefTels
of water containing males, of which the fe-
minal veficles were quite turgid, not one fe-
tus out of fo large a number ever came to per-
fecflion. We muft therefore conclude, that
not a drop of feed w^as ever caft upon them,
iince we have feen that a fmgle drop is fuf-*
ficient to impregnate great numbers.

N 3 CHAP.

1 82 DISSERTATION II.

CHAP. III.

ARTIFICIAL FECUNDATION OF THE TREE-
FROG, AND THE GREEN AQUATIC FROG.

CXXXVIII.I WAS obliged to confine my-
felf to a few experiments on
the tree-frog, as well as on the water-newt,
jiot on account of the difficulty of bringing
the fetufes to perfedlion, as v/as the cafe with
refpeift to that diminutive quadruped, but on
account of the few I poiTeffed when I was en-:
gaged in thefe experiments. All the infor-
mation therefore which I am able to give the
reader^ confifts in affuring him, that my at-
tempts to produce artificial fecundation were
fuccefsful with four couples of the tree-frog^^
both when the feed and the juice of the tef-
ticles was employed.

I fhall therefore proceed to the green aqua^
tic frog, a fpecies with v/hich its prodigious
abundance in the plains about Pavia has ena-
bled me to make as many trials as I could
wiih. But in the firft place, let me dwell a
fnoment upon the defcription of the parts of
generation belonging to the male^ thofe of

the

DISSERTATION II, 1 83

the female, have been already defcribed in the
firft chapter of the foregoing differtation.

After the abdomen has been opened, and
the inteilines removed, the bladder, the femi-
nal veficles, and the tefticles appear in fight.
The firft of thefe parts lies very near the
anus, and is apparently divided into tv^o lobes,
though it has in reality one cavity, for it may
be evacuated by opening either lobe. When
the bladder is full, it partly covers the femi-
nal veficles ; but v/hen the urine is evacuated,
they are ieen very diftindtly. They lie a little
higher than the bladder, and confift of a thin
membrane, through which the feed is feen;
it has the tranfparency of water. Each of the
veficles is provided towards the top with a long
appendix, v/hich is inferted in the epidydimis,
and may be called the vas deferens. Four
tefticles have been fometimes obferved in the
newt, an obfervation which I have had occa-
Con to verify. But frogs and toads are never
fo richly provided. In the prefent fpecies
there are two tefticles,, which have the colour
of the yolk of an egg, and are externally gra-
nulated like thofe of toads -, they are very full
of juice at the feafon of amours, as are alfo the
feminal veficles (cxx).

cxxxix. I ufed both the feed and the juice
of the tefticles for artificial fecundation. My

• N4 firil:

184 DISSERTATION II.

iirfi: trials confifted in impregnating tadpoles,
recently taken out of the uterus of living fe^
males, with the recent prolific fluids of the
male. I afterwards ufed thefe liquors, after
they had been kept and were approaching to-
wards putrefadion, upon tadpoles in like cir-r
cumftances. Laftly, I tried the effedts of
mixture with different fubflances. Thefe
heads comprehend the experiments related in
the foregoing chapters. The event was the
fame, with the exception of a few flight va-
riations. The prolific liquors of the green
aquatic frog preferved their qualities longer
than thofe of toads y but they do not fo well
refift the adion of fudden heat. The feed of
toads, expofed to the temperature denoted by
32° for a few minutes, did not lofe its virtue
(cxxxi), but that of this frog did in my ex-
periments. The prolific liquors of the frog
preferve their efficacy when mixed with more
human urine than thofe of the toad will bear.
The tadpoles of the frog fooner lofe the capa-
bility of being fecundated in the uterus of the
dead female than thofe of the toad. Such
are the principal differences.

cxL. I nov/ proceed to an account of fome
new experiments, which I hope will be ac-
ceptable to the reader. I had on all occa-
fipns either completely covered the mucus

which

DISSERTATION II. iS^'

Xvhich fiirrounds the fetufes with the prohfic
liquor, by means of a pencil, or immerfed
them in a quantity contained in a -watch-
glafs, fo that every part was moiftened. But
is it to be fuppofed that they muft be fo ex-
actly covered ? The queftion was of import-
ance, and experiment alone could decide it.
The mucus is not drawn out into long cords
as in toads (xlv, lxviii), but is moulded
into balls or globules, of which each con-
tains a tadpole. Thefe balls, when taken out
of the uterus, may be eaiily feparated. I
bathed fome ail round, others only over one
hemifphere, and others over one-third of
their furface; and immediately put them into
water. The animation of all thefe tadpoles
proved, that it is not neceffary to cover more
than a part of the m^ucous fpheres with feed.
The tadpoles of this fpecies are round; one
hemifphere is white, the other black (xiv).
Does bathing the mucus v/hich is oppofite to
the black or the white hemifphere produce fe-
cundation moft certainly ? Or is this an in-
different circumftance ? Experiment I'hewed,
that which ever part is moiftened with feed,
the tadpoles are evolved alike.

In my laft trials I had not bathed a fmaller
portion than one-third of the furface. But I
(lid not ftop here. I reduced the fpace more

and

l86 DISIERTATION

11^

and more, till there remained not above the
point of a pin, and even of a needle, which I
dipped into feed, and then brought once into
conta(fl: with a ball; and yet fecundation as
readily followed, as when the globules were
covered ajl over. I was next curious to know
whether a quantity of feed fo inconfiderable
v/ould fecundate the tadpoles lying conti-
guous to the fphere that I touched. I placed
twenty-four globules in twelve watch-glalfes
full of water j the two globules in each glafs
layclofe to one another, and the vifcidity of
the gluten kept them in this iituation. I
then touched, with the point of a needle
dipped in feed, one ball in each glafs. But
as twenty-two tadpoles came to perfedlion^
it appeared that every drop of feed had im-
pregnated tv/o. I repeated this curious ex-
periment with the fame. quantity of feed, and
alfo with a fmall addition. In the former
cafe the number of tadpoles that grew to per«
fedion was double of that of the balls that
were touched: in the latter it always was;,
nay, when two globules were brought inta
eontad: with that which was touched, the
tadpoles of both were very often evolved.
The feed therefore of the great aquatic frog
is fo powerful, that the fmalleft drop is fuf-
ficient to impregnate feveral tadpoles.

CXLU

DISSERTATION II. 187

c:^Li. Confidering that in this furprizing
lexperiment the fmall quantity of feed mufl
have paiTed through the mucus, before it
could fecundate the tadpoles, 1 thought it
worth while to try what would be the con-
fequence of doubling: the thicknefs of this
fubflance, and uiing the fame portion of feed.
Having put with this view fom.e iingle glo-
bules in watch-glaffes, I laid hold of the mu-
cus with a fmall pair of forceps, and ftretched
it about an inch. After fxxing it in this fi-
tuation, I touched the extremity once with
the point of a needle dipped in feed. The
tadpoles fometimes were fpoiled, but they,
not infrequently, came to perfe6liun, an evi-
dent proof that the drop of feed had traverfed
the whole thicknefs of the gluten, for as it
was extended in an horizontal direction, it
could not be fufpedled that it had run down
the outiide.

The next experiment bears a clofe relation
to this. About fifty globules were put into
a glafs-tube hermxCticaily fealed at the bot-
tom. The tube was placed in a vertical po-
ll tionj and a ftratum about an inch thick of
gluten was placed at the top , the gluten was
fo fixed, that it rofe towards the circumfe-
rence, and was deprefied in the center, and
thus it formed a kind of funnel* Upon this

1 88 DISSERTATION 11^

was dropped a little feed, and as foon as it
was loft (which foon happened), the gluten
was removed, and the tubes were placed in
water. When the quantity of feed was not
exceedingly fmall, almoft all the tadpoles
were animated, at other times feveral fpoiled.
I repeated the experiment, fubftituting the
* white of an egg in the place of the mucus.
But then not one tadpole was evolved. When
I put a little upon the globules, it grew pu-
trid and communicated the fame fermentation
both to gluten and tadpole.

The two firft experiments related in this
paragraph, fhew the wonderful efficacy of the
femmal liquor of the frog, though in fuch
fmall quantity in penetrating into the mucus,
and paiTmg through it without lofing its vir-
tue. This pha^nomenon muft be either ow-
ing to the pores of this fubftance, or to ca-
pillary tubes wrought by Nature, in order to
imbibe the feed and tranfmit it to the body
of the tadpole. The white of the egg being
defio-ned for the firft nourifliment of the
chicken, an animal widely different from the
tadoole, muft neceffarily be conftruded dif-
ferently from the mucus, which affords nou-
riihment to the tadpole. Hence it is eafy to
comprehend why the paffage of the prolific

liquor

DISSERTATION 11. 189

liquor through the white is impoffible, while
it is fo eafy through the gluten.

cxLii. But if we are flruck with furprlze
by the fmall dofe of feed which is capable
of etfedling impregnation, the following ex-
periments will very much increafe this emo-
tion. In the cxxxivth paragraph I inti-
mated that this fluid, when mixed with wa-
ter preferves its efiicacy, but I poftponed the
particular difcuffion of this matter: I fhall
now^ enter upon it. In my firft trial, equal
quantities of the feminal liquor and water
were ufed. Finding that this mixture was
fit for m.y purpofe, I doubled the proportion
of water. In every experim^ent I employed
what was afforded by the veficles of one
frog, which never exceeded three grains.
But the effedl was heightened very much by
this increafe of water, infomuch, that twice
the number of tadpoles was evolved : Not
that the water concurred in producing this
difference by any virtue of its own, but be-
caulc the feed was fo much attenuated^ that
it might be fpread over twice the number of
tadpoles. For the fame reafon, when the
water was in the proportion of four to one,
three hundred cam.e to perfedtion, whereas
when thefe fluids were in equal quantities,
not more than one hundred were evolved. ,

This

ig6 DSXSERTATioK ii»

This fortunate refult gave me courage to try
the mixture of a pound of water with three
grains of feed. And here my fuccefs was
greater than I could have conceived. To my
aftonifllment almoft all the tadpoles furniflied
by the uterus of two females, were brought
to life by being immerfed in this mixture.

Convinced that admh'ation fometimes takes
fuch ftrong hold of an objed; as to hinder
reafon from confidering it properly, I fought
to leifen it by a reflecfbion. When I put the
tadpoles into water, they funk^ as ufual to the
bottom, where they were held by the mucus ^
Now did it happen that the fperm, heavier
perhaps than water, fell to the bottom, ex-
affly upon the fpot on which the tadpoles lay f
If fo, fecundation v/as not produced by feed
diffufed through fo much water, but confined
to a much narrower compafs. By this fup-
poiition, fhould it prove true, the wonder
would be very much leflened^ The way I
took to determine this queftion was, to mix
the feed of another frog with a frefh pint of
water. Now fuppoiing the fpeeific gravity of
the former liquid to be greater, it would go
to the bottom in the fpace of an hour; At
the expiration of this time I fixed tadpoles at
various heights in the water. If we fuppofe
that the feed fell to the bottom, it is obvious

that

DISSERTATION II. 19I

that thofe only which lay there would be im-
pregnated. They were indeed impregnated,
but at the fame time all thofe which occu-
pied different ftations were like wife im.preg-
nlted, not excepting thofe which were at the
lurface. Nor could I perceive that the low-
eft had the advantage of being evolved in
greater proportion. The confequence is ob-
vious, the feed did not fall to the bottom,
but was diffufed equally through the mafs.
The firft furprize therefore returns. Three
grains of feed may be diluted in a pmt of wa-
ter, without lofmg their ftimulating power !

cxLiii. The reader wdll eafilyguefs, that
after having carried the experiment fo far, I
fhould ftill urge it onwards, and employ Quan-
tities of water fucceffively larger, till the fe-
cundating virtue ihould be diminiflied or de-
ftroyed, for it is natural to im.agine that this
muft happen at laft. I therefore next em-
ployed eighteen ounces inftead of twelve, and
the tadpoles placed at different heights did as
well, and were nearly as numerous as before.
But the produdi: w\as lefs in tvv^o pounds of
water, and about one-third lefs in three, four
pounds were ftill m.ore prejudicial. But not-
withftanding this diminution of effecl:, I could
not help wondering when I faw that even

upon

J92 DISSERTATION if.

Upon the addition of twenty-two pounds of
water, a few tadpoles came to life.

cxLiv. We have akeady feen how fmall
^ quantity of pure fperm fuiiices, a drop taken
up by the point of a needle! (cxl)* This
truth appears with ilronger evidence, when
three grains are diffufed in twelve, and in
eighteen ounces of water (cxlii, cxliii).
But the fads which I am now to adduce,
prove yet more forcibly than a quantity in-
finitely fmaller will produce the fame efFed:^
How diminutive mull: be the particles of feed
comprehended in a drop of water fcarce viii-
ble, and taken from a mafs of water of eighteen
ounces, in which three grains of the feminal
fluid have been diluted, the reader may ima-
gine. They are, notwithftanding, capable
of producing fecundation. 1 dipped the point
of a needle into this mixture, and touched
feveral globules with it. The diameter o(
the drop taken up was about one-fiftieth of a
line. To my great furprize the tadpoles fre-
quently grew to perfedion. And what added
ftrenp-th to this emotion was^ to find thatthofei
imbedded in globules touched at one point,
were. evolved jufl as w^ell, and as fpeedily^
as thofe of others immerfed in pure feed*

cxLv. Having feveral pounds of water,
containing each three grains of feed^ I was

unwil-f

DISSERTATION 11. 193

unwilling to lay them afide before I had made
fome further experiments. I firfl: tried, whe-
ther the w^ater is rendered fterile by the fe-
cundation of a number of tadpoles; As many
globules as a pound of water would contain
were immerfed in it; they amounted to feve-
ral thoufands. After they were taken out,
others were throw^n in; and thefe came to
life juft as well as the former; and fo did
others afterwards immerfed. I \vas w^eary of
repeating the experinient before the w^ater
loll its efficacy. I kept an account of the
tadpoles of fifty frogs, which were fuccef-
fively put into this water without impairing
its prolific power. -

I next tried, whether the fetufes of froo-s are
brought to life fooner by a long continuance
in the water* A pound was divided into
equal portions, and in one fome globules were
kept immerfed for a fecond, and then put into
pure water; at the fame time, other globules
were put into the other portion and left in it^
but there did not appear to be any difference
in the evolution of the tadpoles.

Lafily, I wifhed to know how long watef^

containing fo fmall a quantity of fperm, pre-

ferves its qualities. It preferves them longer

than pure feed- It would impregnate tadpoles

' thirty-five hours after the mixture, when the

Vol. II. O ther-

T94 DISSERTATION It,

thermometer flood between 17° and 19° {a)
in my apartment. In an ice-houfe, in which
the thermometer fiood (i^) 3°!- above the
freezing point. I have before obferved, that
putrefaction probably deftroys the proHfic
power of the feed (cxxxi). And iince it
does not fo foon run into this degree of fer-
mentation, when divided by a large quantity
of water^ we eafily underftand how it comes
to retain its virtue longer.

cxLvi. From the cxLth to the cxLvth
paragraph, I have related experiments, made
with th,e fperm of frogs, without mentioning
the juice of the tefticles* But it muft not be
fuppofed that I have negledled to make ufe of
it 5 the Angularity and beauty of the enquiry
in v/hich I was engaged, required that it
fliould not be overlooked* I employed this
juice in every trial mentioned in the prece-
ding paragraphs ; whenever I opened the fe-*
minal veficles of a frog, I at the fame time
took out its tefticles. I was thus eafily enabled
to remark the refults afforded by each of thefe
fluids, and if there w^as any rem^arkable dif-
ference, it could not fail to ftrike me; but
no fuch difference was ever perceptible. I

(«) I7==7c|, i9=::74|:ofF.

may

DISSERTATION II. I55

may here clear up a doubt fuggefted in the
cxxvth paragraph. I there obferved, that
the juice of the tellicles of the terreftrial toad
with red eyes and dorfal tubercfes^ impreg-
nated in Ukc circumftances a fmaller number
of tadpoles than the feed, I was fpeaking
of it when mixed with other fubftances ; and
I fubjoined, that it was not in my power to
determine, whether the defed: was to be
afcribed to inferiority of efficacy, or to its
thicknefs, a quality which prevents it from
being fpread over fo large a furface. The
addition of other fubftances, but efpecially of
waterj fliews, that the latter is the true caufe.
I have found on many trials^ that the juice of
the tefticles, as well of the frog as the toad,
imparts to water as great efficacy as an equal
quantity of the feed.

cxLvii, I muft not omit to mention ano-
ther circumftance of fome importance. The
great abundance of each fpecies of toad men-
tioned in the two preceding chapters^ w^hich
has fallen into my hands in the courfe of the
prefent year, has enabled me to make as many
experiments with them as with the green
aquatic frog ; and I have obferved no eiiential
difference in the refults. Frogs and toads
conftitute but one genus ; they copulate and
propagate the fpecies in the fame manner 5

O 2 the

19^ DISSERTATION lt»

the refemblance of the organs bf generation
in both fexes is veryclofe^ the fetufes are
impregnated in the fame way ; they are ahke
imbedded in mucus : fo many marks of affi-
nity eaiily enable us to comprehend, why ex-»
periments fo numerous and various afford
correfponding refults*

Before I conclude my account of thefe at-
tempts to effedt artificial fecundation, I muft
make two obfervations- Every experiment
is not crowned with fuccefs alike* Suppofe>
for inftance, five hundred tadpoles to be bathed
with the feed of a frog or toad, and other five
hundred with that of another* Let the
quantity of this fluid be the fame in both
cafes, and imagine the fetufes to be taken
out of the uterus. The efied: will certainly
follow; we may be fure that the tadpoles will
be evolved; but we cannot be equally fure
that the fame number, or nearly the fame
number, will be evolved; for it fometimes
happens, that the whole of one five hundred
come to perfedion, while half of the other
or more faiL So it falls out likewife when
they arc left to nature, as I have frequently
witnefled when I kept thefe animals in vef-
fels, in order to difcover the fecret of im>*
pregnation, and any follower of fuch pur-
suits may obferve the fame thing in the open

fields^

DISSERTATION II. I97

fields. In May we may fee in the ftagnant
waters, in which frogs celebrate their amours,
fome tadpoles that have lately quitted their
mucus and are fwimming about, while others
are ftill involved in it; but they fhew figns
of animation, and are feemingly eager to break
loofe from their confinement. If we fix our
attention upon the latter, we fhall perceive
in the heap globules not clear and tran-
fparent like thofe which contain living tad-
poles, but turbid, and of a muddy white co-
lour; they have no motion, nor are they
elongated like the others, but remain at reft
and preferve their original round fhape. The
filTures upon the furface are evident figns, that
the fetufes will never grow to perfection.
The fame obfervation miay be made upon the
long ftrings of toads. This partial failure
may be traced to two fources : it may arife
either from the feed or the tadpoles. If every
part of this liquor fliQuld not be equally pro-
lific, the whole will not produce fecundation.
Part alfo of the tadpoles may be vitiated, and
incapable of being im.pregnated.

My fecond remark relates to the diiFerence
of time requifite for evolution. Though they
ijiould all be taken from the fame fituation,
^nd all equally covered with feed, yet they wiU
not all be ecjually forward in their growth.

O 3 There

Ip^ DISSERTATION II.

There will be fometimes the difference of a
few hours, and fometimes of a whole day.
It may be ohferved, that of the lateft more
fail than of the others. This circumftance
guided me in my enquiry, whether a fmaller
quantity of feed did not produce fuch fpeedy
effects. This did indeed now and then take
place, but m.y often repeated trials convinced
ine that it was but feldom. Upon the whole,
thofe which were impregnated with a larger
quantity of feed were not more advanced, and
in a few inftances they were not fo forward.
Upon weighing the feveral fa(fls which I ob-
ferved, I was obliged to conclude, that a
larger or fmaller quantity of feed is an indif-
ferent circumftance in this refped. The tar-
dinefs of evolution feemed to be owing to the
caufes fpecified above.

cxLViii. I fhall conclude the chapter^^
with an anfwer to a queftion often alked con-
cerning artificial fecundation. Many lovers
of experimental inveftigations have enquired,
whether the tadpoles and newts which I
brought to life, exadly refembled, both ex-
ternally and internally, thofe which are the
produdion of pure nature; and whether I
was certain, that they lofe the fliape of a
.worm in order to acquire the form of the
foecies. When iirft I was thus interrogated,

I waS;

DISSERTATION II. I99

I was acquainted only with the few refults of
my iirft experiments made in ijjj, and con-
fequently could not give a fatisfactory anfwer.
The hneaments appeared to be very much
ahke, both in the produfts of art and thofe
of nature j but I had not then conceived any
idea of making a particular comparifon be-
tween them. After I had obtained my pur-
pofe of bringing thefe animals to life, and they
had grown to maturity, I w^as willing to en-
quire further, though I faw no reafon for fup-
poiing that artificial fecundation ihould alter
the lav/s of Nature. The comparifon was
however made in the prefent year (1780), and
I can confidently affirm, that upon the moft
minute examination I have never difcovered
the fmaileft difference, either in the external
or internal parts 5 both the one and the other
have undergone the accuflomed change at the
time appointed by nature, the tadpoles be-
coming frogs and toads, and the young newts
lofing their gills and producing their legs.
It is therefore evident, that artificial fecunda-
tion does not produce the fmaileft altera tioa
in the ceconomy of thefe animals, but that
^very thing proceeds in the fame regular te-?
aour as in natural fecundation*

O4 CHAP,

aOO piSSERTATION II,

C H A P. IV.

REFLECTIONS.

CXLIX. TTITHERTO I have feldom

•^ ^ departed from the duty of the
mere hifloriaH; a duty which I have dif-
charged with the greater pkafure, fince the
facts I had to relate had the recommendation
of novelty. But it is now fit that I fliouid
affume the charader of the philofopher ; that
I Ihouid analyze and compare thefe fad:s, and
employ them not only for the further illuf-
tration of fome truths v/hich I have eftabliflied
relative to generation, but alfo for the ex-r
plana tiori of different pha^nomena accompar
iiying this admirable function. The follow-
ing refiedions will, I hope, contribute to
this purpofe.

I. That the females of feveral amphibious
animals contain in their uterus fetufes com-
pleatly generated before the approaches of
the male, is one of the principal propofitions
fliewn in the preceding diflertation. It i^
proved at length in paragraphs xviii, xix-

^XX, LIV, LV, LVI, LVII. LXXII. XCI.

It is confirmed in tl;g cxxviith paragraph
- ° of

DISSERTATION IT. 201

:bf this dillertation. Hence by paragraphs
ex, CXI. are deftroyed the two famous fyf^
tems of the Epigenefifts and the Vermiculijh^
The fads related in the prefent differtation
furniih a new proof, or rather a demonftra-
tion of their falfliood. Let us take a fhort
view of the queflion. Thofe who confider the
fpermatic worms as the immediate authors of
generation, mufi; of necelfity fuppofe, that
they exift in the feed whenever fecundation
takes place. It is therefore obvious, that
according to this fyftem the feminal fluid
will be unprolific, when it is totally defti-
tute of thefe inhabitants. And indeed its
advocates admit this. But it does not agree
with fads. Though in the feed of the ani-
mals fo often mentioned vermicul'^ may be
generally obferved^ yet in that of two toads
they were entirely wanting; but it impreg-
nated tadpoles, juil as well as the feminal
fluid of other individuals, however well
peopled that might be (cxxii). In the
next place, when the feed of the frog or the
toad is mixed in equal quantity with human
urine or vinegar^ the worms are all deftroyedw
The feed, however, as I obferved in the pro-
per place (cxxxiv), did not lofe its proline
power. It retained this powTr when a few
grains v/ere mixed with twelve ounces of wa^

ter.

202 DISSERTATION IT.

ter, and even with eighteen, though I could
not diftinguilh a iingle fpermatic worm, fo
thinly were they difperfed through that large
body of water. It ought Ukewife to be ob-
ferved, that in feed long kept, which yet
anfwered the end juft as well, 1 often found
the worms dead, and floating upon the fluid
of the veiicles, and like wife upon the juice of
the tefticks. Lajftly, I could eafily bathe
tadpoles with feminal liquor abounding ia
worms, and yet prevent them from having
the leaft concern in fecundation. When a
drop is put upon the objedl-glafs of the mi-
crofcope, every part of it is full of worms.
But when a little evaporation has taken place,
they begin to quit the circumference, and af-
femble towards the center, as the animalcu-
les of infuiions ufually do. As evaporation
advances, they continue to fly tovv^ards the
center, though many are caught, and died in
the dried part of the drop. At this time I
could take up with the point of a needle, at
the edge of the liquor, many drops that were
entirely deftitute of worms. That I might
be quite certain, I placed what I took upon
another obj eft glafs 3 and when I found that
it was quite free from worms, I touched fe-
veral tadpoles, and found that they came to
perfedion, My long experience in the world

of

PISSERTATION II. 20^

of microfcopical animals, whether belonging
to man or animals, will, I hope, vouch for
me, that I was not deceived in this dclicat^i
invefligation. Thefe fid:s 'prove then irre-
fragably, that the fyftem of Lewenhoeck
and his followers is falfe,

CL. This fyftem, it is true, had been at-
tacked by many naturalifts, among v/hom
Vallifneri, my illuftrious fellow-citizen, is
entitled to particular praife. But if we con-
fider their arguments we fhall iind that they
are rather alluring, if I may ufe the expref-
fion of the great Verulam, than convincing.
Pialier alone, the immortal Haller, has, in
my opinion, produced an infuperable objec-
tion againft the fpermatick worms, conlidered
as the authors of generation. It is deduced
from his celebrated difcovery of the con-
tinuation of the membrane of the yolk wdth
the inteftines of the chicken. Now as the
yolk exifted in the hen before ihe received
the cock, {o did the chicken likewife before
fecundation. Whence he drew this corol-
lary, that the chicken had no dependence
upon the fpermatic v^^orms, v/hich pafs from
the cock to the hen. This inference, how-
ever juft and direct It m.ay appear, has not
efcaped the fubtle cavils of fom.e, who have
obiefted the potTibility of an inofculation be-

tweeQ

*^04 DISSERTATION 11.

tween the membrane of the yolk, and the
fpermatic worm coming from the male,
whence they derive the continuation between
that membrane and the inteftines, obferved
by the phyfiologift of Berne, He, how-
ever, in his great work, and, after him, the
acute Bonnet, have fhewn how unphilofo-
phicaj fuch a fuppofition is. But it is cer-
tain, that no fuch objediion can be made to
my obfervations on tadpoles, both becaufe
they exift before fecundation, and becaufe in
experiments, in which artificial fecundation
was produced (cxi,ix)j, the fpermatic worma
were not prefeat.

CLi, This fmgular mode of impregnation,
equally demonftrates the falihood of Epige-
mefis;, or of that fyftem, which ha3 bqea
faifed from the dead, proteded and careifed
by Buffon; who, by means of his organic
^okculei, has created an imaginary organiq
world, as his countryman Defc^rtes had he-.
fore conftruded the whole mafs of exiftences,
feoth organic and inorganic, with his fubtle
piatter. The fpermatic worms having firft
ftruck his fenfes,, and being thence trans-
ferred to his fervid and creative fancy, loft
their former name of animals, and acquired
the new title of organic molecules. What
violence has been oifered to nature by this.

t)tS5ERTATI0N II. JOJ

unintelligible metamorphofis, I need not now
attempt to lliew, having treated the fubjed:
at length in my fecond 'Ejfay on the Natural
Hijiory of Animals and Vegetables, But if I
admit, for a moment, the reality of this ex-
travagant opinion, it will follow, that v/hen-
ever the feminal liquor of animals is deftitu'te
of worms, it muft, according to this re-
nowned naturalift, be alfo deftitute of orga-
nic molecules. And as fecundation and ge*
aeration depend upon the various combina-*
tions of thefe molecules, feed that does not
contain any of them muft be unfit for fuch
purpofes. In the inftances mentioned in the
cxLixth paragraph, the feed of frogs and
toads muft therefore have been unproliiic^
which is dlrecftly repugnant to faft,

CLii. II. The confutation of thefe fyf-
terns confirms more and more this important
truth, that the young belong originally to
the female, while the male only furniflies a
fluid, which determines them to affume mo-
tion and life* I would not indeed affert^
that thefe little organized bodies are without
motion before they experience the adlion of
the mafculine liquor* From the time at
which the tadpoles in the ovaria fall under
the cognizance of the fenfes, till they are
about to be impregnated, they grow con-

iiderably.

206 DlSSERfAtiON li.

fiderably, Infomiich that they are many times
larger at the latter than at the former period.
Now growth implies nutrition^ nutrition the
circulation of the fluids, and circulation de«
pends on the pulfatidn of the heart; I there-
fore conceive, that, previoufly to the influ-
ence of the feed, there was a beginning of
motion and life, but in a degree exceedingly
dull and languid, from the extreme flownefs
of the movement of the fluids; but this idea
occurred to Haller and Bonnet before mco
Hence tadpoles would never be fo rapidly
evolved, or attain that fenflble animation^
V/hich we denominate life, if they were not
llibjeded to the influence of the feminal fluido
This raifes them from a 'ftate of apparent
fhapeleffnefs and immobility, and protjuces
a due unfolding of the limbo, and evident
motion, and active life.

But the feed, in order to exert its power
Upon tadpoles, muft penetrate into them ^
for it is not likely that it can produce anima-
tion by mere impreilion upon the ikin. Are
the paths by v/hieh it enters perceptible to
the eye? I have bellowed much attention
upon this queftion, and the repeated in^
ftances of Mr. Bonnet have ftill further en-
gaged me in fo difficult an enquiry. I there-
fore examined fome mucilaginous globules

difcharged

DISSERTATION II. lOj

dlfcharged by frogs, with a weak microfcope.
The mucous cover was fo tranfparent, that
I might have fuppofed the tadpoles to be na-
ked, if I had not been fure of the prefence
of the gluten. But I could not perceive any
pore or aperture either on it or the tadpoles.
Neither did a glafs of more highly magnify-
ing power ihew any fuch appearance. I next
ftripped the fetufes of their mucus, but dif-
covering nothing in thofe globules that were
full, I determined to try whether evacuating
them would contribute to the fuccefs of my
enquiry. Making, therefore, an incifion
with a fmall fcalpel, I preiTed out all the fe-
mifluid matter lying v/ithin, fo that nothing
remained but the empty Ikin or membrane.
This was examined firft with a v/eak and then
with a powerful lens, when there appeared '
an immenfe quantity of lucid points, which
may reafonably be fuppofed to be (o many
pores. I faw^ the fame apertures upon the
tadpoles of toads. This fuppofition, there-
fore, iliews how the feminal fluid enters into
the body of the tadpole through innumerable
mouths. The prefence' of thefe apertures
upon every part of the Ikin, explains a pha?-
nomenon before mentioned, v/hy fecundation
takes place , whatever part of the globule,
whether that which correfponds to the belly,

or

^OS B I S S E R T A T I O N jf,

or the head, or the tail, be touched with
feed; for when this fluid has ttraverfed the
gluten, it is fure to meet with paths prepared
for its entrance.

CLiiii III.. Thofe^ who have fuppofed
that the fetufes are not generated during the
a6t of fecundation, but that they pre-exift
long before, and are contained within the
female, have explained their animation, by
imagining, that the feed of the male enterv«;
into the fetus, and reaches the heart. By
gently irritating the cavities of this organ, it
excites alternate dilatation and contradlion^
and thus the fluids are forcibly impelled into
their refpediive veffels. Hence follow, as fo
many neceffary confequences, the dilatation
^of the veffels, an increafe of the quantity of
fluids, a great irritability of the heart, an
univerfal expaniion of the folids, and con-^
fequently the growth of the animals both in
bulk and mafs. Such is the docftrine de-
livered among others by Haller and Bonnet
in their ufeful productions, and long before
them ValJifneri, who deferves the si:reater
praife, iince he was unacquainted with the
facts that direclly prove the pre-exiftence of
the germ, and v/as guided only by the twi-^
light of conjed:ure. When I confider the.
ivident pulfation of the heart, which is pre-
vious

DISSERTATION 11. 209

Vious to the leaft motion in any of the limbs,
the evohition of the veffels and of the whole
animal, which is confequent upon the a6lion
of this mufcle, its irritability, — that property,
by virtue of which it refumes motion, when /
ftimulated by any mechanical agent, at a
time when there are no remains of irritability
in the other mufcles, all thefe circumftances
induce me to adopt the opinion of thefe
writers. I fliall, therefore^ w^ith them con-
iider the feminal fluid as a ftimulus, which
penetrating to the heart, and powerfully irri-
tating the internal parts, excites more fre-
quent and flronger pulfations ; whence arife
that manifeft exteniion of parts, and that
animation which ever follow impregnation.

Both • thefe effects are influenced by the
temperature of the atmofphere. The faga-
eious reader eafily conjedtures^ that they
will fooner take place in v/arm weather, and
later in colde Tadpoles fecundated early in
the fpring, as thofe of the terreftrial toad
with red eyes and dorfal tubercles, require
feveral days to appear 5 and if the heat fl:iould
be only a few degrees above congelation^ ten
or eleven are necefiary. On the contrary,
the evolution of the tadpoles of the fetid
toad and of froes is very auick> for they are
ffcundated ia May and June. I once ob-

JP fervecj.

2IO DISSERTATION II.

ferved, that when the thermometer flood at
21°, they became animated in lefs than
twenty-four hours ; whereas thofe of the very
fame fpecies (viz. of the green aquatic frog)
did not arrive at this ftate till the fifth day,
when the temperature of the air was about
13° [a). The fame variation is obfervable
in the fstuies of the water-newt, of fcalv
fiflies, the tortoife, the crocodile, and in
general of oviparous infects : and what is
truly furprifmg and fcarce credible, the dif-
ference of temperature has the fame effed:
upon the eggs of birds, of which it might
be imagined, that they could not be hatched ;
but in a determinate heat, fuch as that of.
the female, which is about 32° {h). In this
temperature the eggs of hens are hatched very
regularly -in twenty-one day^. But by a di-
minution of the heat, Mr. Villers, a fenfible
naturalift of Lyons, has retarded the appear-
ance of the chickens to the 25th -, and Mr.
D*Arcet, by increafing the w^armth, has
hatched them on the 13th day.

CLiv. IV. I have had occafion to make a
fmgular obfervation upon the feed of the frog
and toad, the proper ftimulant of the heart of
the tadpole. It is diftinguiihed by tw^o pro-
perties from the feminal liquor of other ani-

{a) 6i|cfF. {J>) 321=104 of F.

malst

't)ISS£RTATION II. 2II

niais. It is as tranfparent as water, and has
not the leaft viicidity. It evaporates nearly
in the flime time as water, and hence would
feem to have no fpirituous parts; as is more-
over evident from its not taking fire, when
brought to the flame of a candle, and ex-
tinguilliing burning coals when it is thrown
upon them. To the tafte it is infipid, and as
it does not effervefce either with acids or al-
kalies, it muft be confidered as neutral. Thefe
qualities would appear to agree but ill with
the nature of a fiimulant, if we underfland
by this term a pungent, cauilic, or fpirituous
fubftance* But this is not the fenfe in which
Haller and his followers confider thofe bo-
dies which ftimulate the heart. They mean
fuch as are capable of irritating the fibres of
this mufcle, by which means it is excited to
motion if at refb, or if otherwife to an in-
creafe of action. To this clafs of ftimulants
belong the blood, water, air> and the feminal
fluid, which will appear to be more powerful
than the fluids previoufly circulating in the
tadpole, if we confider the flownefs of their
motion*

CLv. V. A quantity of feed far more in-'
confiderable than v/e fhould ever have ima-^
gined, is fufficient to animate a tadpole. We
have feen^ that it is not neceilar}^ to cover the

P % fetu§

SI2 DISSERTATION If.

fetus completely with this prolific fluid. A
drop v/ili fuflice (cxl). Further, three
grains mixed with twelve, and even with
eighteen ounces of v/ater, communicate to
every part of it the power of fecundation,
fince tadpoles placed in any part of the
mixture are im.pregnated (cxlii, cxliii)„
The three grains of feed muft therefore have
been diffiifed through the whole mafs of wa-
ter/ But what an enormous divifion of its
particles muft fuch a diffufion occafion ?
Hovv^ fmall a portion of the prolific liquor will
fall to the ihare of each tadpole ? Yet there
are facfts which prove, that the femen ftill re-
tains its virtue after this exceflive divifion;
for I have found a globule one-fiftieth of a
line in diameter taken out of a mixture of
three grains of feed, with eighteen ounces of
water, w^as often capable of fecundating a
tadpole (cxLiv). Defirous of knowing the
proportion which the tadpole (that of a frog
is two-thirds of a line in diameter) bears to
the particles of feed diffiifed in a drop of this
dimenfion, I have found, on calculation, that
lit is as 1064777777: I. How infinitely
fmall, therefore, is the quantity of feed in
comparifon of the bulk of the fetus which
it fecundates ! This deduction led me to
^^alciilate tbe weight of the particles of

femen

DISSERTATION tl, 21 3

femen difperfed in this drop of water: it is
I994-6S7500 of a grain. That I might view thefe
particles under every poflible afped:, I reduced
their bulk to cubic lines, when it appeared
to be about equal to jz^ri^rr^ of a cubic
line {a) .

{a) This note will fiievv hmv I obtained thefe numbers. AC-
fuming with Metzius, that the circumference of a fphere is to
its diameter as 355 : 113, the folid contents of a fphere | of a
cubic line in diameter will be zz— X-^-^^— zz^-^i^i? of a cubic

^7 I 1 3 >. 6 9 ' 5 3

line, and this will be the bulk of a tadpole to be fecundated.

The Iblid contents of a fphere ~ of a line in diameter are
z=: ' ,■ X ^l^.. ^=^^~^~7;^y and this will be ihe mafs of tha

12,5000 ii3;-;6 84.750000' *

drop cjf water mixed with leed.

The folid contents of a cylinder which has 37 lines for the di-
ameter of its bafis, and is ^c lines hiph, are zzl^^^^ '^^-'^J-^:^lll 5

•J J o ' ^ ^ 1 1 3 ;•, 4. '

and this is exadvly the volume of water weighing iB ounces, in
which three grains of feed have been dropped.

The folid contents of a cylinder of which the bafe is one line
in diameter, and the heieht 10 lines, is izl^ii-^-LizzlXlS • and
this is the volume of the three grains of feed.

Now fuppofing that the feed is equally difFufed in the water,
the volume of water with the feed, at!d the volume of the drop
of water mixed with feed, will be proportional to the weight of
all the feed, and to the weight of the feed mixed with the drop
of water. Hence, as the weight of all the feed is three grains,
it will appear from the rule of three, that the weight of the
feed diffufed in the drop of water is zr ^ of a p-ratn.

^ 2,9946b7500 gJM-iij*

As in homogeneous bodies the weight is directly as the bulk,
having the weight of the whole feed and that of the feed mixed
with the drop of water, we Ihall find by the rule of three^, tha^
the bulk of the feed contained in the voiumb of w^ter i§ nearly
—-— --VT-TTrT: of a cubic line.

2 003, 1 2 042 o

If we now compare the bulk of the tadpole with that of the
(eed contained in the drop of water, it will appear to be. as.
1964777777 : ;.

P 1 CT.yr,

114 !> I S S E R T A T I O N II."

CLvi. VI. Here I may be afked, how a
portion of femen fo infinitely fmall can make
fuch an irnpreflion upon the heart of a tadpole
as to accelerate its palfations and increafe
their ftrength, and thus to quicken the mo-
tion of the fluids and animate the whole
fyftem. I reply, that there are not wanting
examples in the animal kingdom to give
countenance to fach a fupppfition. A drop
of the poifon of the viper, introduced into a
wound, is fufficient to deftroy the irritabiUty
of the mufcular and the fenfibility of the
nervous fyftem, and to caufe the death of any
animal whether great or fmall. A man, a
dog, an horfe, or an ox, are deftroy ed juft as
certainly as a fparrow, a goldfinch, or a moufe.
If we confider for a moment, the proportion
between the bulk of the venom and that of
an horfe or ox, we fliall not be lefs furprifed^,
that fo fmall a quantity of poifon Hiould be
fatal to thefe great animals, than that fo mi-
nute a portion of feed fhould animate one in-
finitely fmaller (^). But we have fad;s that

more

(i$) I cannot but remark^ that the author has been fomevvhat
unfortunate in the example which he has chofen for the purpofe
of illuftration. Fontana has proved, by numerous experiments,
that the effects of the venom of the viper are diredly as its
quantity, and invjsrfely as the buik of rhe poifoned animal.
This is very ftriking in his trials on dogs, of which the fmallep
fpecies were always deilroyed by the fgime quantity that fomeo

DISSERTATION II. 21^

more diredlly prove, how very fmall a quan-
tity of f^ed may produce a coniiderable irri-
tation of the heart. A grain of ftorax thrown
upon the fire will fill a whole room with its
odour. The particles therefore muft be dif-
perfed, through every part of it, and notwith-
ftanding their extreme minutenefs, are capa-
ble of vellicating the nerves of the nofe, and
exciting the idea of a particular fmell. This
vellication is fo ftrone, as to occafion fneezino:
in fome perfons of the more delicate fex. If
then the inconceivably minute exhalations of
certain bodies make fach impreffions upon
our organs, why fliould we wonder that a
few particles of feed prove a ftrong ftimulus
to the heart of the tadpole, an organ fo much
more fufceptible of external impreiiions, as
it is more finely framed than ours ?

CLvii. VII. But the quantity of feed re-
quifite for the animation of a tadpole has its
limits; it is not infinitely fmall.' I have ex-
prefsly obferved, that the quantity above fpe-
cified, w^as fi^eqiiently fufficient for the pur-
pofe (cxLiv, CLv). Whence it is to be
inferred, that it fometimes failed. The di-
minution of the dofe of feed afforded a miore

times killed the middle-lized, and fcarce ever the large ones.
From the data afforded by his experiments he calculates, that
the poifon of feveral vipers is requiiite to deilroy the life of a
pan J and a fiill larger quantity to kill an ox,

P 4 decifive

2l5 DISSERTATION II,

decifive proof. I put a drop of this fluid
upon a fmooth pane of glafs, and drew it out
with the point of a needle, into a fine and
almoft invifible filament, fometimes an inch
long. I then took feveral mucous fpheres
and rolled them fometimes along half, fome-^
times along a third, at others along a quar-
ter of this filament. This experiment is
analogous to another related in paragraph
CXLI1I5 where I obferve, that if three grains
of feed be diluted in two or three pounds of
water inftead of a pound and a half, fewer
tadpoles will be evolved, and that the num-
ber continues to decreafe in proportion to the
increafe of the quantity of water. The por-
tion of feed then neceifary to produce fe-
cundation, muft amount to a determinate
quantity.

I am notwithflanding of opinion, that the
quantity of feed which effecfls impregnation
is fmall beyond conception and nearly ap-
proaching to what is fpecified in the CLvth
paragraph. Hence I am inclined to believe
that the furplus does not contribute at all to
fecundation. My opinion is founded upoa
the following confiderations. As fecunda-
tion is an indivifible operation, if the fuper-
abundance contribute to promote it, it caa
only be by haflening the animation and

growth

DISSERTATION II. ZIJ

growth of the tadpoles. This muft be in
confequence of a greater number of particles
excitins: the heart to fl:ron2:er vibrations.
But fach a notion is repugnant to facts ; there
is no difference either in the time or the de-
gree of evolution, v^hether the fetufes be en-
tirely covered with pure feed, or only touched
with an infinitely fmall drop (clxiv). I
caninot therefore imagine, wdiat purpofe the
iurplus of feed can ferve, and am obliged to
conlider it as ufelefs. Nor is it difHcult to
comprehend, how an invifible particle only
may be capable of producing fecundation if
it be confidered how inexpreflibly fmall is
the area of the veflels which it enters, for
canals fo narrow muil refafe to admit above
a very minute portion.

CLviii. VIII. But a very obvious ouef-
lion occurs here. As thefe amphibious ani-
mals are animated by fuch a trifling quantity
of feed, may this difcovery be extended to
iifhes, birds, quadrupeds and man ? Or may-
it be aflerted in terms ftill more comprehen-
five, that nature employs only fo inconiider-
able a portion of feed for the fecundation of
animals in general ? The queilion is curious
and interelling, but cannot I think yet be
iblved for wane of data. I. am aw^are, that
ihis opinion is poijlble^ nay^ that the flriking

inilance

2l8 DISSERTATION n;

inftance before us renders it in fome meafure
probable. I cannot, however be certain, that
it is really fo, when I refled: upon the multi-
plicity of means employed by Nature to attain
the fame end. Perhaps, therefore, this fo-
vereign Artift may allot various quantities of
feed for fecundation, according to various
qualities of animals. But ia order to difco-
ver whether flie really admits fuch variety, I
can imagine no other. way than that of com-
parifon. Let us, for inflance, compare what
happens in the amphibious animals which are
the fubjecl: of thefe DilTertations, with v/hat
takes place in other claffes, as in fifhes, in-
fedis, birds and quadrupeds. The know-
ledge derived from fuch different inftances,
may enable us to fix our ideas with fome de-
gree of fafety. We have, I believe, but tv/o
difcoveries on artificial fecundation, that of
Mr. Jacobi^ inferted Berlin Memoirs {a)y
and mine, But without any defign to lefien
the merit of that naturalift, I may be allowed
to fay, that from his experiments we can
only conclude, that artificial fecundation took
place in the two fpecies of fifh of which he
fpeaks. Thefe were the falmon and trout.
After putting their mature, but unimpreg-
nated eggs in clear water, he let fall upon

(a) Tom. 20,

them

D 1 S S E R T A T I O N II. 219

them feed from the milt of the male till the
water began to grow white, In about five
weeks the young fiihes made their appear-
ance. This is the amount of the whole pa-
per of Mr. Jacobi. It affords no inform.ation
concerning the prefent queftion, fmce the
German experimenter has not afcertained,
with any degree of precifion, the quantity of
feed necellary to produce fecundation. In-
ftead of doing this, he has flopped at the iirft
ftep, and has iiniflied his trials juit w4iere an
inquiiitive naturalift would have begun them.
But if experiments on artificial fecundation
are not yet fufhciently numerous to afford the
neceffary data, we cannot expecfl; them from
natural impregnation. A fmall fliare of in-
formation concerning the generation of man
and animals wdll convince us of this truth.
It remains, therefore^ that we profecute the
experiments upon artificial fecundation in a
rational manner, Befides the light which a
feries of weil-devifed experiments w^ould caii -
ypon the problem propofcd, it would cer-
tainly clear up many cbfcurities in the hiftory
of animals. My enquiries relate to an order
,of beings, in which we are certain that fe-
cundation is external. But I invite natura-
iifls to beftow part of their attention and fa-
gacity upon that incom^parabiy more piume-

rous

J220 DISSERTATION II.

rous clafs of which it is equally certain, that
this function is performed within them. Of
thefe, fome, as is well known, are ovipa-
rous, others viviparous. It will be proper
to keep fome females apart from the males,
and to obferve the time at which they lay
their eggs. We may then make upon the
eggs fuch experiments as are defcribed in
this Dillertation. I do not think it will be
difficult to adapt them to viviparous animals,
if we ufe different means, and fuch as will
ad: internally, nor do I fee any reafon to de-
fpair of fuccefs. Attempts, apparently more
arduous, have not difappointed the hopes of
the adventurous enquirer, and fuch unex-
pe<fl:ed inilanees of fuccefs have occaiioned
revolutions in natural philofophy.

GLix. IX. The feed, agreeable to the
principles of Mr. Bonnet, is not only the fti-
mulant, but the nutriment of the fetus.
The proofs of his opinion are thefe. • The
organ of the voice in that mule, which is the
product of the mare impregnated by the afs,
very clofely refembles that of the male parent.
If the germ exift in the female before im-r
pregnation, it mufl have been a horfe in mi-
niature, and not a mule or an afs ; the organ
therefore of the voice ought to correfpond to
that of the horfe and not of the afs, The

feed

DISSERTATION H. 2 21

feed muft then have modified the organ of the
voice in the germ according to that of the
male parent. In conformity with this model,
the parts of this organ grov^ and are unfolded;
yet v^e know the afs contributed only a fluid.
It is therefore neceffary to admit, that this
fluid nouriflies the component parts of the
larynx, and that it is incorporated with their
fubfl:ance, lince growth is the natural and
immediate efFed: of nutrition. The fperm
then is not a limple ftimulant, it is moreover
a nutritive liquor. The naturalift of Geneva
ftrengthens his deduction by the inftances
of the grow^th of the beard in man, of the
crefl: of the cock, and the horns of the flag,
which are certainly owing to the efiicacy of
the feed.

Haller, in his great work, agrees only in
part with the before -mentioned philofopher.
He allows that thefe phenomena depend
upon the feed, not indeed as a nutritive li-
quor, but as an impelling or ftimulative
principle. The evolution of the hair, the
•horns, and the creft, is owing to the fperm,
which, being received again into the blood,
excites the heart, by its alcalefcent acrimony,
to attenuate by flironger pulfations the vifcid
juices, and to impel them into the fnall
veiTels, by which means the prexifting germs

of

.222 DISSERTATION 11.

of the hair and the horns pullulate, and th^
creft grows to a larger fize [a). With regard
to the organ of the voice in the mule, its
evolution arifes from the greater power in the;
feed of the afs than the horfe, to unfold and
enlarge the parts (^;). It appears^ therefore^
that according to the Swifs phyfiologiftj a
ilimulating quality alone is fufficient, not
only for the animation of the fetus, but alfo
to explain thofe phisnomena, which, accord-
ing to Mr. Bonnet, require, that the feed
iliould be confidered as nutritive. I fhall
not prefame to decide between thefe great
philofophers. I venerate their merits, and
am better qualified to admire than to judge
them* I will only obferve, with the utmoft .
deference, that in the frog and toad the
proline fluid cannot be fappofed with any
probability to perform the office of a nutritive ^
principle. I intreat the reader to call to
mind vmat is faid in paragraph clv, about
the proportioil between the bulk ot the feed
and that of the tadpole ; it is nearly as ii
1064777777. Suppofing, therefore, the tad-
pole to be nouriilied by the feminal fluid, its-
growth would not exceed the bulk of the feed/
that is to fay, it y/ould be next to none. It
may be added, that if the nutrition of thg
tadpole, at the commencement of evolution,

i^a) £i. Ph^'f. L xxvil. Sea. 3. U) L. c. lib. xxix. Sedt'.-z.

came

DISSERTATION II. 22^

came from the feed, liiofe which were be-
dewed with the greateft quantity of this fluid,
ought to grow faftefl and be evolved fooneft.
Yet we know, that a tadpole touched with
the moft inconfiderable drop, and one covered
compleatly with this fluid, do not difl'er in
this refpedt (cxliv). I therefore, from my
experiments, cannot ailign to the feminal
liquor any other quality, befides that of a
ftimulant.

Though the preceding obfervations afford
the ftrongefi: reafons for believing, that the
feed is a real ftimulus to the heart of the tad-
pole ; yet, as this is a mere hypothetical
opinion, I was defirous of fubmitting it to the
teft of experiment. Refledting, that the
ftimulating power of any fubftance muft be
enhanced by increafmg the adlivity of its
parts, and that this end may be attained bv
heat, I determined to warm the feminal fluid,
and then to moiften fome tadpoles with it.
With this view I mixed three grains of the
feed of the frog with half an ounce of water,
and having heated it. to 30° {a), I immerfed
twenty tadpoles in it, and immediately after-
wards removed them into pure v/ater, in.
v/hich the thermometer flood at 17°. That
I might have a term of comparifon, I fecun-

(^) 30«=:99f, and 17=70! of F.

dated

a24 DISSERTATION IH

dated other twenty tadpoles with the fame
iiii^ture, after it had acquired the tempera-
ture of the atmofphere. The device was not
ineireduaL The tadpoles fecundated in the
heated mixture, were ten hours more for-
ward than the others, a phasnomenon which
1 cannot but attribute to the greater energy
and ftronger ftimulating power ariiing from
the action of heat.

CLx. X. The ftimulating power, whicB
animates the embryo, is not loft, though the
feed ftidtild have been kept fome time after it
has^ been taken out of tlie body. This hap-
pens alike, whether it be kept unadultered or
mixed with other liquors (cxxxi, exLv).
It is truly wonderful that a fingle drop fliould
not be loft> when mixed with fo large a body
of v/ater (cxlii, cxliii). Will the feminal
liquor of other animals preferve in like manner
its efficacy ? For want of fads w^e muft have
recourfe to conjecture. The prefent inftance
rnay be an exception to a general rule and con-
iined to a particular clafs, in which fecunda-
tion is external and takes place in water, and
on this account the feed is expofed to circum-
fiances, never experienced by that of other
animals. But, on the other hand, it is pof-
fible that thofe properties may belong to other
feminal fluids. In my fecond Ejfay on the Na-
tural

DISSERTATION II. 22^

iiiral HiftOTy of Animals a?2d Vegetables I ob-
fcrve, that the feed of raan, and various qua-
drupeds, does not become corrupt for feveral
hours after it has been taken from its natural
receptacles. I confirm this obfervation by
flievving,/ that the worms continue to fwim
about brifkly for fome time, provided it is
kept properly heated. If, therefore, the feed
of man and quadrupeds preferve its natural
qualities under thefe circumftances, v/liy may
it not alfo retain its ftimulating power, which
is the caufe of fecundation ? And if ioy is the
famous ftory of Averroes, concerning that un-
fortunate queen, who became pregnant after
bathing, without any commerce with man^
lb very ridiculous ?

CL CHAP.

2Z6 PISSERTATION II,

CHAP. V.

WHETHER F'ECUNDATION IS AN EFFECT
OF THE AURA SEMINALIS. WHETHER
OTHER LIQUORS ARE CAPABLE OF FRO-
DUCING FECUNDATION. TRIALS TO
PROCURE ARTIFICIAL MULES IN THE
AMPHIBIOUS ANIMALS IN QUESTION'.
ARTIFICIAL FECUNDATION OF THE
SILK-WORM. ATTEMPT TO IMPREG-
NATE A BITCH ARTIFICIALLY.

CLXLTX/'H ETHER the grofs vifible
' ^ part of the feed be neceffary to
the fecundation of man and animals, or,
whether the inviiible attenuated part ufually
called the feminal vapour or aura, be deftined
to this purpofe, is a very ancient queftion,
and ftill continues to be debated every day.
Thofe phyiicians and philofophers who fa-
vour the latter opinion, are obliged to main-
tain it from a fort of apparent neceffity, ra-
ther than by any diredl reafons or experi-
ments. They refled: upon obfervations made
by diligent anatomifts, who have found the
vagina of fome pregnant women either very
narrow or entirely clofed. They attend alfo
two other numerous obfervations, from which

it

DISSERTATION II, 227

it would appear, that at the time of impreg-
nation, the feed does not reach the uterus.
Laftly they refle6l, that the orifice of the
ovidudls, or Fallopian tubes, is fo narrow,
that it will fcarce admit air, much lefs a
probe. They conclude, that fo many ob-
ftacles muft prevent the feed injedled into the
female organs from arriving at the ovarium,
where the embroyos are lodged. Hence it is
fuppofed, that fecundation muft be eii^edled
by the volatile part of that liquor, which
either reaches the ovarium by the way of cir-
culation, or by rifing through the mouth of
the uterus and along the tubes. Notwith-
ftanding thefe arguments, many other authors
adopt the oppofite opinion ; they think, that
the grofs part of the feed operates impregna-
tion, iince the narrow pafTages are enlarged
during the ardour of enjoyment, and fince
there are not wanting inftances where feed
has been found in the uterus, in the tubes,
and even to have afcended as high as the
ovaria. That the uterus, fhould often, after
coition, be found without the fluid of the
male, they ccnfider as an objection of no
weight, becaufe the obfervation was probably
made after too long an interval, when the
feminal liquor had paiTed out of this cavity,
or becaufe fo fmall a quantity had entered

0^2 into

228 DISSERTATION IJ.

into it as to efcape the notice of the in-
fped:or.

Such nearly are the argunusnts on each fide,
but they are, in my opinion, infufficient to
decide the difpute; the former, beeaufe they
do not irrefragably prove that the volatile
vapour alone reaches the ovaria ; the latter,
beeaufe though the grofs part iliould arrive
there, it ftill remains doubtful w^hether the
animation of the embryo is effedled by this,
or the attenuated part. To cut ihort all con-
troverfy, it v^ill be neceffary to feparate the
aura, and to fubjed; the fetus to its influence
for then it v^ill either be impregnated, a
manifeft proof in favour of the feminal ex-
halations, or it v/ill not, and we may con-
clude, with equal certainty, that the fenfible
part is neceffary to fecundation. But this
mode of deciding the queftion has not, I
believe, occurred to any one, or at leaft I
do not know that any one has reduced it
to pradice. But from the facility of making
experiments with the feed of the animals con-
cerning which I have been treating, this ap-
peared eafy to be done.

CLXii. The reader will recolledt what has
been before faid of the efficacy of feed, after
it has been almoft infinitely divided. A drop
©f w^ater, one-fiftieth of a line in diameter,

taken

DISSERTATION II.' 229

taken from eighteen ounces of water, with
which three grains of feed are mixed, is capa-
ble of impregnating a tadpole (cxliv). This
experiment is apparently favourable to the fe-
minal aura, which, in the general opinion,
is nothing but the vapour of the feed exceed-
ingly rarefied. The fad:s, however, which
I (liall adduce, clearly prove the contrary.
That I might moiften tadpoles abundantly
with this exhalation, I put a quantity of feed,
amounting to eleven grains, taken from feve-
ral fetid toads, into a watch-glafs. In another
fomewhat fmaller, I placed twenty-fix tad-
poles, which were fixed very firmly to the
bottom by the tenacity of the gluten. I then
inverted it over the former, and in this fitua-
tion both glaifes v/ere left five hours in my
apartment, where the liquor of the thermo-
meter ftood at 18°. The femen lay exadily
under the tadpoles, and they could not but
be involved in the rifing vapours, for the dif-
tance was little more than a line. Upon in-
fpe(5ting the tadpoles at the expiration of the
fifth hour, I found them fo much covered
with moifture, as to wet my finger when I
touched them ; the moifture was the eva-
porated part of the feed, which had loft one
^rain and half. The tadpoles, .therefore, had
been bedewed with one grain and half of the

0^3 feminal

2^0 DISSERTATION IlJ

feminal aura, for it cannot be fuppofed to
have efcaped out of the glaffes, they fitted fo
clofely. The tadpoles, notwithftanding they
were placed immediately in water, and left
there feveral days, all periil>ed.

CLxiii. Though this experim^ent Is un-
favourable to the aura, yet it ftood alone, and
I could not avoid further enquiry. One
grain and an half ought indeed to fecundate
many thoufands, much more twenty-fix, I
hovv^ever chofe to increafe the quantity of
vapour, which could be done by only in-
creafing the heat. Placing every thing ex-r
a-dlly as in the former experiment, I fet the
glafles in the window, v/here the heat of the
fun, being moderated by the glafs through
which it ihone, amounted to 35°, and could
not therefore be prejudicial to fecundation.
In four hours the fpheres were fo covered by
the vapour, that drops were feen hanging
from them, But'the eiFect produced was the
fame as before.

I repeated this experiment once more, not
fo much with a view bf confirming the for-
mer refults, as to fee whether the feed, after
part had been refolved into vapour, retained
its tefficacy. After the tadpoles were moi-
ftened v/ith the exhalation, half of them were
put, as beforejj into water, all which came

m

DISSERTATION II. 2^1

to nothing. The other half were bedewed
with a Uttle of the refiduum, and then put
into water : they almoft all came to perfec-
tion. Thefe experiments fhew, that the va-
pour of the feed of the fetid toad is incapable
of impregnating the young, and that the feed,
after a confiderable evaporation has taken
place, is ftill efficacious.

CLxiv. Both thefe confequences were con-
firmed by fubfequent experiments. The fpace
between the tadpoles and the fperm was about
a line : that the vapour might be more effica-
cious, I reduced it to one-third of a line -, but
ftill to no purpofe.

I have already obferved, that by the aura
feminalis the vapour of the feed is generally
underftood. Some phyfiologifts think that
this exhalation confifts of the odoriferous par-
ticles of that fluid ; others that it is the moil
attenuated part, and others again that it is a
very fubtil fpirit. Whatever it be, it is cer-
tainly incapable of producing fecundation.
Yet as fo fubtil a fpirit might be thought to
efcape at the meeting of the glaifes, I deter-
mined to obviate this fufpicion by cementing
the edge of the upper glafs to the iniide of
the other. I moreover fubftituted a Uttle
glafs-funnel in the room of the upper watch-
glafs;^ and cemented it as before^ the fmaller

0^4 orifice

232 DISSERTATION IT.

orifice was hermetically fealed. The tadpoles
were faftened to the neck, and the furface of
the feed was enlarged that evaporation might
be the quicker. I thought that the conical
form of the funnel would coUecTt the aura into
the point vv^here the tadpoles lay. This new
apparatus, was kept fix hours in a heat of 26%
and the fetufes were furrounded continually by
the vapour, but the event was fl:ill the fame,
and the refiduum was alfo efficacious ( c l x 1 1 1 . )
' When I tried the efiects of the aura in open
veffels, where the air had free accefs, I found
it juft as ineffectual as ever.

CLxv. My laft experiment made with, thla
view was to colled: feveral grains of the eva-
porated fluid. I then immerfed twelve tad-
poles in it, and left them feveral minutes.
Twelve more were touched with the refi-
duum, Vv'hich did not exceed half a grain,
but eleven of thefe grew to perfedion, but
not one of the others.

Thefe various fatls concur to prove, that
fecundation in the fetid toad is not the effedt
of the aura feminalis, but of the fenfible part
of the feed. But my enquiries have been
extended further 5 the abundance of the toad
wil^i red eyes and dorfal tubercles, and of the
green aquatic frog, has afforded me ample
opportunities of repeating upon them the

experiments

DISSERTATION H. 233

experiments defcribed in paragraphs clxit,
CLxiii, CLxiv, CLXv. Eut the aura ap-
peared on all occafions incapable of producing
fecundation. My few trials upon the tree-
frog agree exad'ly with the others. -

CLxvi. As I had found the juice of ths
tefticles equally powerful with the feed, it
was proper to make trial of its aura. I had^
ufed this juice with equal advantage, when
pure and when diluted v\ath water. I have
evaporated it under both thefe circumfcances
in the fame manner as ftcd ; but always to no
purpofe : whence it was neceffary to conclude,
that this aura is juft as inert as that of the
feed.

My experiments on thefe two fpecies of
aura were made in the fpring and fummer of
1777, and I then gave intimation of them to
Mr. Bonnet, as may be feen by fome extracts
of my letters, inferted in the ufeful annota-
tions on the third volume of the new edition
of his works. I repeated them in 1780, with
the fame refult.

Thus then it appears, that in two fpecies
of the toad, and as many of the frog, fecun-
dation is not the effect of the aura, but of
the grofs part of the feed. But are we to
fuppofe that Nature obferves this rule in ani-
iTxais and man .^ Spund logic does not allow

us

234 DISSERTATION II.

US to deduce from fo few fads a conclufioa
fo general. But thefe fads lead us to think
the fuppofition probable. It is at leaft certain,
that we may venture to admit it, till contrary
fads flhall be adduced. And thus the great
queflion, whether fecundation is the eifed of
the aura feminalis, is clearly decided in the
negative, . with refped to fome animals, and
with probability with refped to the reft.

CLxvii. I may here obferve, that it ap-
pears from this, as v/ell as the preceding
chapters, that the part of the feed which is
capable of effeding impreg-nation is not, as
many fuppofe, a fpirituous liquor, of great
volatility, and liable to lofe its virtue when
expofed for fome time to the air, after which
there remains nothing but an effete matter,
a kind of caput mortuum, as is incident to
many liquors, produced both by art and na-
ture, which, on this account, are kept care-
fully itiUt up in veffels. But nothing like
this happens to the feminal fluid, though it
be expofed to the air for feveral hours ; and
after half had been driven off in vapour, the
remainder was juft as fit for fecundation as
that which had been recently taken from the
veiicles. The prolific liquor, to which thefe
obfervations are applicable, may be compared
in fome meafure to water. Whether this

element

P I S S E R T A T I O N II. 235

element evaporates, either from agitation of
the air, or the adion of heat, the refiduum
retains the nature and properties of the whole
mafs. But vv« may, on the other hand, re-
mark a great difference. The vapour of
water, when collected, poileffes every property
of water never fubmitted to this procefs,
whereas the vapour of feed, though it may
be condenfed into a liquid, does not retain its
fecundating power. It muft therefore be
fuppofed, that the particles, when feparated
from the whole mafs, acquire fome bad qua-
lity, which difqualifies them for occafioning
fijch an irritation of the heart of the embryo,
as. will produce animation^ though the mi-
nutenefs of the particles does not allow us to
inveftigate the origin and nature of this bad
quality.

CLxviii. I now proceed to the difcuffion
of another problem, which will appear both
new and extraordinary. It was propofed by
Mr. Bonnet, in a letter concerning artificial
fecundation. And although he was aware of
its extravagance, he did not heiitate to com-
municate it, in order that it might be put to
trial. I cannot explain his idea better, than
by laying before the reader an extraft from
his letter of the 15th of Auguft, 1778. *^ I
will not conceal from you a vifion that has

found

23^ DISSERTATION 11.

found its way into my head. Mr. Senebler
muil: have informed you of the fine experi-
ment of Mr. Achard, who has fubftituted
eledlricity, in the room of heat, for hatching
chickens, and has fucceeded at ieaft in part.
If the electrical fluid be capable of caufing
the evolution of the chicken in the egg, it
muft be owing to an acceleration of the velo-
city of the fluids, or, what amounts to the
iame thing,. lO an increafe of the irritability
of the heart. Now I think I have given
ample proDf, that the feminal liquor fecun-
dates the germ, by exciting the irritability of
the heart. 1 could wifh then, my dear Mal-
pighi, that you would fubilitute the eledlrical
fluid in the ftead of the femen. Should an
experiment fo original facceed, the fecunda-
tion would be far more artificial than that
which you have fo happily efi'ected. You
may well imagine that I will not anfwer for
your fuccefs : it is probable., that the ekvftrical
fluid cannot perform the office of the feminal
liquor I but we have feen fo many unexpeded
events happen in the organized kingdom that
we cannot pronounce with too much caution
concerning the impoffibility of any experi-
ment, more efpecially of fuch as relate to
this fubjed.— Should we have fufped:ed, that
the polype pofleflbs fuch fJarprifing proper-
ties ?

DISSERTATION II,' 25/

ties ? And after the difcpvery of tlie polype,
who would have fufpedled the reproduction
of the head of the fnaii ?"

Such were the exprcffions of this profound
contemphtor of Nature. But various occu-
pations of another nature having prevented
me from continuing my obfervations on arti-
ficial fecundation, it was not in my power to
attempt this ftrange experiment, till the fum-
mer of the prcfent year (1780). To confeis
the truth, I doubted exceedingly of its fuc-
cefs, not fo much for the reafons adduced by
my celebrated friend, as on account of the
ftriking difference between Mr. Achard's
eggs, which had received the influence of the
male beforehand, and the tadpoles which had
not been fuhjed:ed to it.

Having placed upon the condudlor a me-
tallic veiiel, containing feveral fetufes both
of the frog and toad, I excited the cylinder,
and fimply electriiied them without fparks or
fhocks. In the firft trial the tadpoles wxrc
eledrified three hours a day for tv/o days fuc-
ceiTively. As thefe became all putrid, I con-
tinued the procefs in another experiment for
four hours on three fucceffive days, but with
no greater fuccefs. I then electrified nine
tadpoles for thirty-three hours in the fpace of
two days and a half, but the event was flili
the fame. Inftead

I3S DISSERTATION II.'

Inftead of placing the tadpoles in the fitua-
tion already defcribed, I fixed them to the
point of a metallic rod arifing from the con-
ductor, knov/ing that the electrical fluid would
now be more concentrated and energetic*
But I was not more fuccefsful, though they
were electrified nineteen hours in two days.
All thefe experiments were made in hot
weather, and the tadpoles fhewed figns of
decompofition in three days.

At the fame time I electrified other im«
pregnated tadpoles : they grew faiier than
thofe which were not eled:rrfied, an event
th-Bt exactly correfponds wdth the accelera-
tion of vegetation, occafioned by the elecftric
fluid. From thefe experiments we may con-
clude, that elecftricity increafes the velocity
of circulation in fecundated tadpoles, but not
in the unimpregnated, probably becaufe its
action is not fo mild and gentle as is neceffary
at this early period, and as that of the femi*
nal liquor.

CLxix. Before Mr. Bonnet imparted to
me his ingenious thought, and indeed at the
time of my firft obfervations concerning ar-
tificial fecundation,- I conceived hopes of
being one day the fortunate difcoverer of
fome fluid, equally efficacious with the fe-
men, though of a different nature. When

I was

DISSERTATION II. 239

I was employed about the impregnation of
the toad with red eyes and dorfal tubercles,
and had dilcovered the efficacy of the feed
taken out of the velicles, I was ftruck, I
know not how, by the thought of trying
fome of the other fluids of the fame animal.
I therefore moiftened fome tadpoles with
blood, others with gall, others with juice
exprefled from the different vifcera, as the
heart, the liver, the lungs ; they were put
into feparate veiTels, and fome of thofe that
had been touched with blood and the juice of
the heart, came to perfedtion. The furprize,
which an event fo unexoedled occafioned,
may be eaiily conceived ; but it may likewife
be fuppofed that I ihould repeat this experi-
ment. But the refult was now very different;
not a tadpole was evolved. The famx ill fuc-
cefs attended many fubfequent repetitions ;
and I was obliged to conclude, that neither
the blood, nor the expreffed juice of the
heart, has any prolific power. But whence,
I fliall doubtlefs be afked, the-fuccefs of the

firfl; experiment ? It arofe from an inadver-

J.

tency which I afterwards eafiiy , detedled.
The tadpoles were taken from an uterus,
which I had touched with forceps, that had
been ufed for taking fome drops of feed out
of the veficles. Not being at that time av/are

of

£40 DISSERTATION IT.

of the efficacy of an exceedingly min-ute
quantity of feed I had not wiped the inflru-
ment very carefully. On this account, it
muft have left an imperceptible portion upon
fome of the tadpoles, that v^ere afterwards
moiftened with blood and the juice of the
heart. This explanation became more pro-
bable, when I found, that of tadpoles taken
out of the uterus with forceps, carelefsly
wiped after they had been dipped in feed, a
certain number was always impregnated ;
whereas this never happened, when the for-
ceps had not touched this fluid, or when
they had been diligently cleaned. This neg-
ligence^ and the detection of its origin, were
excellent prefer vatives againfl: the commiffion
of like miftakes in future. They may alfo
ferve as warnings to thofe who ihall be de-
firous of repeating my experiments on arti-
ficial fecundation, or of attempting others of
the fame nature.

CLxx. Convinced of the inefficacy of thefe
liquors, I laid afide at that time all thoughts
of trying others. My unfuccefsful experi-
ments with the eledrical fluid, renewed the
fame train of ideas ; but it was rather leafl I
ihould have reafon to reproach m.yfelf for
having too foon quitted a purfuit entirely new,
than with any hopes of fuccefs, that I re-
fumed

DISSERTATION II, 24I

fumed thefe experiments. Giiided by the
great principle, that fecundation is the con-
fequence of irritating the heart by the feminal
liquor, I was led to try acrid and ftimulating
fluids, fuch as vinegar, diluted fpirit of wine
and urine ; but thefe fubftances hailened the
corruption of the tadpoles, inftead of fecun-
dating them. The juice of the lemon and
citron produced the fame effecfts, though
their acidity was weakened by the admixture
of water. In the rind of thefe fruits there
is a ftimulating fpirit, which upon fqueezing,
fpirts out in little jets, and takes fire when
thrown into the flame of a candle. But this
fluid, as well as many others, which I
ihall forbear to enumerate, was totally ineffi-
cacious.

CLxxi. We learn, both from ancient and
modern hiftory, that the feed of one fpecies
of animal, frequently impregnates the em-
bryos of another, when there is a near re-
femblance between them. A third fpecies,
ufually denominated mules, is the fruit of
this impregnation. Thus the male goldfinch
produces with the female Canary bird, ^ii
intermediate fpecies -, as alfo does the white
peacock with the common fort ; and the
pheafant with the hen. Among quadrupeds,
the mules, which are the offsprings of the

Vol IL R afs

242 DISSERTATION IT.

afs and the mare, or the horfe and the fhe-
afs, are the moft common. And the cele-
brated Bourgelat has now eftabUjflied, be-
yond a doubt, that the wolf propagates
v/ith the bitch. Nor is it always neceffary,
that the two fpecies feould be very nearly
allied. For wherein confifts the clofe refem-
blance between the afs and the cow or be-
tween the bull^ the fhe-afs, and the mare ?
Yet the recent and certain obfervations of
the fame French Naturalift, have proved,
that the lingular fpecies of animal called the
Jumart {a), is produced by the copulation
of thefe widely differing quadrupeds, after
its exiftence had been queftioned by modern
writers, and exprefsly denied by Buifon [b),
Thefe inftances led me to entertain hopes,
that I fhould obtain intermediate productions
by impregnating the embryos of one fpecies
with the prolific liquor of another. In irij ^
Profpedus I propofed to enquire, what v/ould
be the event of attempting fuch experiments
on aquatic and amphibious animals, bearing
little refemblance to each other (c). If they
f-tould happen to be fuccefsful, it is obvious,
N how muph fuch irregular produdions would
contribute to illuitrate the obfcure function
of generation. I have

{a) CEuvre.s des Charles Bonnet, Tom. V. {h) Hii^. Nat.
Tom. XIV. (0P-5»-

DISSERTATION IT. 243

I have.profecuted thivS inquiry, but witli
fmal] fuccefs. Ilaving repeatedly moiftencd
the embryos of frogs and toads with the
feminal tinid of the newt, and reciprocally,
evolution has not taken place in any one in-
ftance. My hopes of impregnating neigh-
bouring fpecies with effed; were much more
fanguiiie. I need not obferve, that the frog
and toad are each amphibious, and that they
nearly refemble one another, as well in exter-
nal appearance as in internal ftru6lure. Belides
this correfpondence of organization, their
manners, anions, and ways of propagation
are alike. Having, therefore, fixed upon the
fetid terreftrial toad, as its feafon of genera-
tion coincides with that of frogs, I bathed
with the feed of this toad, the tadpoles of the
green aquatic and the tree frog, and in return
with their feed, I moiftened the tadpoles of
the fetid toad. I did the fame with the froo-^
juft mentioned, and the toad defcribed in the
cxxvith paragraph. The feed, as well as
the juice of the tefticles, w^as employed
fometimes pure, and lometimes diluted with
water. But notwithftanding fo m.any and
fuch ftriking marks of reiemblance, one
fpecies could not be fecundated by another.
If I did not wonder, that liquors effentially
differing from feed were not prolific (clxix,

R 2 CLXX),

244 DISSERTATION II.

CLXx), I muft own my furprlfe at finding
that fpermatic liquors, which muft needs re-
iemble each other very clofely, were ineffica-
cious. Thefe experiments, however, though
ineffedlual, are not uninftrudive; they teach
us, that from analogy we cannot learn when
we may procure intermediate produdiions.
In general we obferve, that they owe their
origin to animals, in many refpecfls, analo-
gous to each other; but fuch analogy is not
a- certain fign of their being capable of pro-
ducing together, as manifeftly appears from
experiment. In this branch of phyfics. as in
numberlefs others, we muft not generalize
our ideas, but are under the neceffity of con-
fulting the oracles of Nature, and receiving
her anfwers with refped: and attention, as
we proceed from one fpecies to another. If
we would obtain illegitimate produdions, we
muft of neceffity employ the feed of a diffe-
rent fpecies. It muft, at the fame time, be
capable of penetrating the embryo, and ani-
mating it by a bland and kindly impulfe.
But we can learn from the effeds alone,
whether any given feed is endowed with thefe
effential properties, and we muft abide ftriclly
by the refult of experiments.

And as if thefe amphibious animals knew
the inefficacy of their refpedlive feminal fluids,

I have

DISSERTATION H. 245

I have never, in the whole courfe of my in-
quiries, icQn them coupled. At the feafoa
of their amorous ardour, I have placed a •
male toad along with a female of his own
fpecies, and a female frog ; v/hen difregard-
ing the latter, he has flown to embrace the /
former. I have then feparated them., and
taken away the female : but the male iliewed
no defire of approaching the female frog, and
feemed to be v/holly bent on efcaping. And
though I kept them together for feveral days,
copulation did not take place, not even when
the female began to difcharge her young, • a
time at which the males are more than com-
monlv ardent, in order to fecundate the fetufes
as they are brought forth. I witneffed the
fame inattention in the male of the fetid toad,
to the female of the green aquatic and tree-
frog, and in the male of the green and tree-
frog, for the female of the fetid toad. I know
that male toads are commonly fuppofed to
copulate v/ith frogs, and that m.any, for this
reafon abftain from eating the latter during
their amours, I, however, have never met
with fuch conjundlions in the whole courfe
of obfervations ; nor did Roefel ever fee an
inftance in Germany. I muft, therefore,
reckon this opinion among thofe number-
kfs prejudices, which have credulity and ill

R 3 grounded

2-4^ ' DISSERTATION I'l.

grounded popular tradition for their only
fupport.

CLXXii. After having finifhed the fore-
going paragraph, with which I intended to
conclude the Diflertation, I read over the
whole from the beginning, in order that I
might correal fuch paffages as required cor-
redion. The CLviiith paragraph induced
me to attempt another experiment. I there
invite naturalifts to try to fecundate fome of
thofe animals, in which it is certain, that
impregnation takes place internally. It was
now July, the feafon deftined for the amours
of the filk-worm {a), in the Modanefe, and
indeed in moft other parts of Italy. I there-^
fore determined to try, whether any portion
of my fuccefs, with different amphibious
animals would attend experim.ents on this
infed:. I recollect, indeed, the failure of the
great Malphigi; nor can it be doubted, that
fiich an inflance may juflly create diffidence
in the boldeft experimenter^ more efpecially
as the celebrated Bibiena was not more for-
tunate, when he undertook to repeat and vary
Malphigi's experiment. As I did not, how-
ever, perceive, that it was impolTible to fuc-i
ceed, I did not think the attempt v/ould argue
any blameablc perfumption in me. The un-

(a) Phalaena Mori. Linn, Syft. Nat.

impregnated

DISSERTATION ZI. 24^

impregnated eggs of the phalx'iia originating
from the filk-worm, may be obtained in two
ways. If the female be kept apart from the
male, they may be collected after they are
difcharged, or they may be taken from the
matrix. The feed is to be taken from the
genital organs of the male. Having procured
fome e?2:s in both thefe wavs. I moiftened
fome of them with a large quantity of feed,
and others very fparingly, but to ViO purpofe.
The fecundated eggs of this infect alTume a
violet colour ; the others remain yellow.
My eggs, before they were moiftened with
feed, were of this colour, and retained it
afterwards ; they moreover became foft, and
an incavation appeared upon the farface, figns
that never fail to attend fterility. Thefe ex-
periments were made with that fpecies, of
which the eggs are hatched only once a year,
viz. in the fpring. And I believe, it was
upon this fpecies, that the great naturalift of
Bologna made his unfuccefsful experiment.

I afterwards tried another fpecies, w^hich
is much cultivated in the cities of Lombardy,
on account of its producing three generations
in a year : one towards the end of the fpring,
another in fummer, and the third in autumn.
My labour was not unprofitable beftowed
upon the eggs of this fpecies. Many which

R 4 I moiftened

248 DISSERTATION II.\

I molftened with feed, produced worms in
proper feafoii; nor is there any caufe to ap-
prehend, leaft I ihould have committed fome
inadvertence in my experiments. As foon as
the laft change of form had taken place, I
put the females under the receiver of an air-
pump ; the males were on the outfide ; and
either the iight or the fmell of the females
allured them to the veffel, for they were con-
llantly fluttering about it. By thefe means,
1 fuppofed that the male organs of generation
would be filled with feed. As foon as the
eggs were difcharged, I bathed them v/ith
feminal fluid. Alany of them, which were
at firfl: yellow, began in a few days to turn
brown, and at length affumed a brov/nilh
violet hue; in about a week they produced
little worms ; thofe which had not been
moifl:ened with feed remained yellow, grew
flaccid, and fpoiled, I procured fifty-feven
at two trials.

CL XXII I. This unexpected event gave me
courage to attempt another experiment. It
fliewed that oviparous animals may be arti-
ficially fecundated. Of viviparous animals
I had before obferved with furprize, the arti-
ficial impregnation in fome fpecies in which
this function is external. It remained there-
fore, as the reader will eafily guefs, to try

whether

DISSERTATION II. 249

whether fuch experiments will fucceed with
thofc viviparous animals in which fecunda-
tion takes place in the body of the female;
an animal of fome fize, fuch as the cat, the
dog, or fheep, feemed fitteft for my purpofe.
This idea had been for fome time fermenting
in my head, and I could not refrain from dif-
clofing it in an article written by me for the
ProfpeBus of the new Italian E?2cyctopcedia^ and
entitled. Artificial Fecundation, Having pro-
pofed fome views refpedling the artificial fe-
cundation as well of plants as animals, I
employed towards the end the following ex-
preffions. '^ Hitherto I have fpoken only
of animals ufually called oviparous ^ artifi-
cial fecundation may perhaps, by diff^erent
means and fuch as would a6l within the
body, be extended to viviparous animals.
The reader underftands my meaning/* In
the CLviiith paragraph of this Differ tation
I threw out the fame idea, and exhorted Na-
turaliflis to put it in pradlice; for after I had
fucceeded fo eafily in impregnating difi^erent
animals of another kind by art, I could not
confider my projed: as very unpromfing.
The event of my experiments on filk-worms,
in which impregnation is internal, rendered
my expedlations fliill more fanguine, and I
immediately fet about to bring them to an

iffue^

250 DISSERTATION II.

iffue. I chofe a bitch fpaniel of moderate
fize (a) which had before had whelps. Su-
fpecling, from certain appearances, that £he
would foon be in heat^ I confined her in an
apartment, where fhe continued a long time,
as will be feen below. For greater fecurity,
that fhe might never be let lofe, I fed her
myfelf, and kept the key the whole time.
On the thirteenth day fhe began to fhew
evident figns of being in heat; the external
parts of generation were tumid, and a thin
fiream of blood flowed from them. On the
nventy-third day fhe feemed fit for the ad-
miilion of the male, and I attempted to
fecundate her artificially in the following
manner, A young dog of the fame breed
furnifhed me, by a fpontaneous emiflion,
with nineteen grains of feed, which were
immediately injeded into the matrix, by
means of a fmail fyringe introduced into the
vagina. As the natural heat of the feed in
animals of warm blood may be a condition
neceilary to render fecundation efficacious, I
bad taken care to give the fyringe the degree
of heat which man and dogs are found to
polTefs, which is about 30° {/?), Two days
after the injection, the bitch went off her

(a) -Canis aq^uaticus, pilo longo crifpo, inflar ovis. Linn.
Syft. Nat, (^) 99 or 100 of F,^

beat.

DISSERTATION II. 25t

heat, and in twenty days her belly appeared
fwoln, which induced me to fet her at hberty
on the twenty-fixth. Meanwhile the /well-
ing of the belly increafed; and fixty two days
after the injection of the feed, the bitch
brought forth three lively whelps, two male
and one female, refembling in colour and
fhape not the bitch only, but the dog alfo
from which the feed had been taken. Thus
did I fucceed in fecundating this quadruped;
and I can truly fay, that I have never received
greater pleafure upon any occalion, lince I
have cultivated experimental philofophy.

CLxxiv. I have before obferved, that nine-
teen grains of feed were injected 3 but it is
proper to add, that the whole quantity did
not pafs into the uterus. Thirteen at moil
arrived there, fmce fix at leafh adhere to the
lides of the fyringe. But vre are not to con-
clude, that impregnation was effeCLed by all
of them. It feems beyond difpute, that a
much fmalier quantity is fufficient. As the
efrect is produced in the ovarium, the feed
muil pafs through the tubes and who does
not perceive, that fome muft be retained by
their fides, as alfo by thofe of the uterus ? A
very fmall portion muft therefore, in this
cafe, have produced fecundation. Com-
bining this experiment with thofe made upon
amphibious animals, in which we have kea

how

252 DISSERTATION IT.

how foiali a quantity of feed fujflices, it may
with great probability be inferred, that the
dofe of that vital liquid, by which nature is
renewed, is always exceedingly minute, as
well in the large as fmall animals. This in-
ference is ftill further confirmed by obferva-
rions relative to birds ; from which we learn,
that a cock fecundates at once all the eggs
Jaid by the hen in twenty days. Hence, as
one is fufficient for twelve or even twenty
hens, he may every day be the father of thirty
chickens (a).

I conclude with a brief refled:ion. Con-
fidering my laft difcovery, I have no difficulty
in believing, that we ihall be able to give
birth to fome large animal?, without the
concurrence of the two kxcs, provided we
have recourfe to the fimple mechanical de-
vice employed by me ; and, at the fame
time, take advantage qf fuch favourable cir-
cumflances as may promote the experiment,
and ufe thofe judicious precautions which
are indifpenfible. Meanwhile, reflecting upon
the phenomena which I have related, I am
inclined to exclaim with Pliny, Mi hi intuenti
(cepe perfuajit rerum Natunz nihil incrediHk-
e^ifdmare de ed.

{d) BufFon, hifloire des oifeaux.
ENP OT DISSERTATION II,

t 253 ]

TWO

LETTERS

FROM

Mr. bonnet, of geneva,

RESPECTING THE FOREGOING

DISSERTATIONS.

ARGUMENT.

A L I T T L E before I delivered to the
"*■ ^ Printer the two DilTertations on the
Generation and artificial Fecundation of dif-
ferent animals, I tranfmitted a French tranfla-
tion of the analytical index to my illuftrious
friend Mr. Bonnet ; for my numerous en-
gagements did not allow me to fend him an
abridgement of the DiiTertations, notwith-
/landing I^ as well as he, very much wiflied
it. The great brevity of my communication
produced effedis, equally advantageous to the
public and myfelf, but fuch as I did not at
all expeft. From its very nature, the index

could

2^4 ARC V M E N T.

could only ferve to convey a fummary of the
contents, and was merely calculated to induce
the reader to confult the work itfelf. When
I confidered that the Differtations would foon
appear, I fuppofed that my friend would he
fatisfied with the imperfed: account I fent to
him. But I was miftaken. " The perufal of
the index excited a defire of fuller informa-
tion concerning feveral particulars : and he
VvTote a long and obliging letter, which drew
from me an anfwer, in which I endeavoured
to reply to the feveral pertinent queftions
propofed by Mr. Bonnet. My^ anfwer v/as
followed by a fecond letter, not lefs polite
and interefting than the former. Such was
the occaiion of thefe two letters. I confider
it as a lingular advantage, that I am authorized
to publifh them ; not merely on account of
their clofe connection with the ©ilTertations,
but alfo on account of their good fenfe, the
philofophical views, and profound refledlions
v/hich they contain; and becaufe they are
recommended by that elegance (if I may be
allowed to judge concerning what is written
in a foreign language) v/hich ever charaderifes
the productions of this writer.

In the fir ft, thofe paflages of the analytical
index, v^hich require explanation, are fre-
quently tranfcribed. It would have been fu-

perfluous

ARGUMENT. 255

pcrEuous to publifli my reply, containing
thele explanations, as I took it from my
book : there the reader will find them, by
having recourfe to the numbers of the letter,
which correfpond to thofe of the Differta-
tion. With this help, he will alfo enter bet-
ter into the reafons and refledlions of Mr.
Bonnet upon thofe paffages of the index, of
w^hich he did not afk for any explanation.

The fecond letter, which relates to my
explanations, is in general very perfpicuous-
In thofe places, both of this and the firft,
which feemed to require fome previous in-
formation, I have placed a, few notes at the
bottom of the page.

LETTER

L E T* T E R i*

Genthod, Nov. 29th, 1780*

My dear Friend,

T WAS going to write to you at the time
"*• I received your interefting letter of the
7th, for which I return you many thanks ^
My healthy it is true, has been very much
difordered this year. In the fummer, I had
two tedious catarrhal fevers, one immediately
fuGceeding the other ; they harraffed me ex-
ceedingly, and very much affedled my weak
eyes. The violent and repeated efforts of
coughing, drove the blood into them in too
great abundance, I could do nothing all
July and Auguft and part of September.
When I was firft attacked, I was very bufy
about my numerous annotations on the Con-
templation, I had gone as far as the tenth
part. I could not refume this eoiployment
immediately upon my recovery ; it required
too much application for my v/eak ft ate. I
therefore fet about the revifal of the different
memoirs I had publifhed in Rozier's JournaL
Hence I was led to compofe new^ ones on
bees, fnails, and newts. They will compofe
the Fifth Volume of the edition in Quarto ;

and

LETTER I. 2^7

and that the prefs may not remain unem-
ployed, I have allowed my editors to print
them as they are fent. The firft volume of
the Contemplatiofi was printed, when they
began the fifth volume. The Comtemplatio?z
will take up the fourth volume. It will be
enlarged about one-third. Hence it became
neceffary to divide the volume into two parts.
It will occupy three volumes in odiavo. You
will eafily believe, that your name frequently
occurs, and I am always highly gratified,
w^hen I have occafion to mention your fine
difcoveries. But I have great reafon to regret,
that I did not fooner receive the fynopfis of
the new experiments you have obligingly com-
municated to me. As I treat in the feventh
and eighth parts of the reproduction of ani-
mated beings, I cannot, as thofe parts are
already printed, introduce many curious
particulars noticed in your index. But I
forefee, it will not be difficult to introduce
many of your obfervations into the chapters
not yet printed. I will, therefore, go over
the principal articles, obferving the order of
your numbers.

I. I perceive that you have found, by many
experiments, that the fetus exifts before fe-
cundation in the green aquatic frog, the tree-
frog, thQ great terreftrial toad, wdth red eyes

S and

2^8 LETTER V

and dorfal tubercles, the fetid terreftrial toad,
and in two fpecies of the water-newts [a).
This (hort lift will doiibtlefs be enlarged, as
foon as your curious experiments are extended
to other fpecies ; as you will always have the
diftinguilTied merit, of having opened fo rich
and beautiful a career. All the dired: means
of proving the pre-exiftence of the embryo
in birds and quadrupeds, have by no means
been employed. I, you know, have never
doubted of this pre-exiftence : all my reflec-
tions upon generation, even in my youth,
led me to confider it as the m^oft univerfal law
of Nature. To contrive, therefore, expe-
dients for expOiing the germ, which is un-
doubtedly contained in the veiicles of the
ovarium of large viviparous animals before
the accefs of the male, is the firft requilite.
Its tranfparency probably contributes as much
as its minutenefs, to render the germ invifi-
ble before fecundation. Whatever would
tend to leffen its /tranfparency, and to coagu-
late the embryo, would bring it within the
power of glailes ; fuch experiments, fo likely
to illuftrate the important and obfcure fub-
ied: of generation, have been little pradlifed;
and I forefce, that if you will but confent to

{a) N° I. of this and the fecond letter, are the only^Numbers
which have none to correfpond with them in the Piffertations.

defcend

LETTER I. 259

defcend into this of mine, you will bring
away unexpected wealth; for Nature treats
you as a favourite child, bccaufe you under-
fland how to interrogate her properly. But
though we fhould, not be able to obtain a
diftind: view of the germ in large quadru-
peds and birds before fecundation, we may
very juftly prefume, from what we moft cer-
tainly know concerning this interefting fub-
jed:, that the germ exiils before impregna-
tion, or that its formation is not owing to the
concourfe of the male and female, but bears
date a primordio. Hallar's demonft ration of
the pre-exiftence of the chicken is not flricftly
dired: : it does not produce the germ itfelf
before fecundation, but eftabliflies only the
continuity of its membranes with the yolk,
which incpnteftibly exifts before fecundation.
This inquiry has, I think, been abandoned
too foon ', it has too haftily been determined
to be beyond the reach of human abilities*
I am perfuaded, that if it had been conduced
with the fame perfeverance, pains, and fa-
gacity, as you have fhewn in your profound
refearches concerning the animalcules of in-
fuiions and amphibious animals, far more
dired: proofs of the pre-exiftence of the germ
in the females of oviparous and large vivi-
parous animals, would have been obtained.,

S z There

26o LETTER I.

There is fome contrivance, not yet conceived
by phyfiologifts, v^hich, the moment they
fhall difcover it, and put it in pradice, will
afford the demonftration we fo much delire.
Men fhould never be in hafle to conclude
that any inquiry is impra(flicable, merely be-
caufe there appears no relation between the
prefent means, and the fad to be afcertained;
for have all the combinations of thefe means
been tried ? If not, who can be certain, that
he is acquainted with all the relations be-
tween thefe means and the fadt, which is
prefumed to exift, and propofed to be afcer-
tained? This refled:ion is ftrengthened by
numberlefs inftances, recorded in every page
of the hiftory of natural philofophy, and
more efpecially of phyiiology. Confider how
many inventions, for which the ancients
would fcarce have dared to hope, even if they
had had a diftant glimpfe of them, have en-
riched thefe fciences ! Could they have ima-
gined, that the artificial fecundation of- the
germs of various animals would one day be
accomplifhed, and that chickens would be
hatched without the aid of animal heat or of
a flove? Need I mention thofe admirable
chirurgical operations, the miracles of the
healing art, which are fcarce credible even to
thofe who behold them ? We are as yet in-

^competent

LETTER I. 261

competent judges of what is impoffible in
philofbphy; for we always decide from our
prefent acquifitions of knowledge, which bear
no proportion to Nature. Nature is immenfe;
the poffible combinations of beings have no
bounds, and the human underftanding is al-
moil always too hafty in its decifions. The
conviffion of our ignorance or moderate at-
tainments, ought to preferve us from despair-
ing of any thing in phyfics ; we fhould fay
to ourfelves, what I cannot difcover, another
will lay open to every eye. But enough upon
a fubjed; capable of affording a fmall volume
of practical reflexions ; it is time to come to
the interefting Iketch of the work you are
about to publifli. I fhall be guided by the
numbers of your paragraphs.

XIII. I find here, that you have imagined
a curious contrivance to prevent the fecunda-
tion of the green aquatic frog. You do not
particularize the experiment, and it excites
my curiofity. I mufl therefore take advan-
tage of your friendly offer, to anfwer the prin-
cipal queftions fuggefled to me by the perufal
of your fketch. You may be fure, that I
fhall make ufe of your anfwers. You fliall be
my oracle, and I am certain that its replies
will be more intelligible and inftrudive than
thofe of the Delphian. How have you con-

S 3 trived

262 L E T T E "R T.

trived to prevent fecundation in this frog?
Probably the experiment has fuggefted new
information concerning the myftery of fe-
cundation; for nothing here Hands uncon-
ned:ed.

XXVI. I cannot here underftand the fenfe
of your expreflions, '^ the fecundation of
the eggs, though effefted out of the body,
penetrates hov/ever a httle way into it/' Is
the action of the feed propagated by the ge-
latinous matter enveloping the eggs ? But I
ought not to try to find your meaning by con^
jecture.

Lix. I am glad that you have diilindlly
feen the circulation of the blood in tadpoles,
before they yet fhewed any figns of motion.
Many other inteftine movements doubtlefs
take place in germ^s, before they are fufficient-
ly developed to move their little limbs. If
germs are all originally enclofed one within
another, many inteftine motions muft have
happened in them fmce the creation. But this
admirable fpedlacle is refer ved for thofe fupe-
rior intelligences, wliofe piercing view pene^
trates into the moft hidden fprings of the ma-
chine of this, world. Much has been faid of
the involution [emboitement') of germs ; the
term is improper: germs are not little boxes
enclofed one within another 5 they muft have

been

LETTER i: 263

been integrant parts of the firft organized
bodies that came from the hand of the Crea-
tor. I have infifted on this point in one of
my new notes on the Contejnplatmi. It is of
confequence to fix the meaning of terms pre-
cifely.

Lxxv, Lxxvi. You are then convinced,
that the eggs of fcaly fiilies lofe by deficca-
tion the power of being produ(fl:ive. You
have feen the fame thing happen to the fiip-
poled eggs of tadpoles j and you conclude,
that the affigned explanation of the repeo-
pling of dried ponds is falfe. I was therefore
miftaken, when in Art. cccxviii. of the-
Confideratiojis on organized bodies^ I thought
of applying to the eggs of fiines what my
illuilrious friend Trembley had obferved with
refped; to thofe of the tufted polype^ which
m.ay be kept feveral months in the dry with-
out lofing the power of producing. I how-
ever threw out an invitation to Naturaliils on
the fubjed of fiilies eggs : I faid, "' that it
would be a curious experiment to keep diffe-
rent fiflies eggs for fome time in the dry, and
then diftribute them in proper places. This
fimple trial would afcertain, w^hether in fuch
a flate they can ferve to perpetuate the fpecies.
Nature is not fubjeded to undeviating exad-
laefs : In her operations there is a latitude

S 4 which

264 LETTER I.

which the Naturahft ought to ftudy, and
which experiment alone can dete6l/' You
have accepted my invitation, and your expe-
riments have not been favourable to my con-
jedure. As you have not pointed out your
manner of proceeding, I am unable to judge
whether it excludes the moft common natural
circumftances in ponds and pools . Many tri-
vial particulars may produce a variation in the
refults. You eafily guefs v^hat I have in
viev^5 |)ut I am not lefs inclined toacquiefce
in the falfehood of my conjed:ure,

Lxxx. Strange "way in which the male
72ewt impregnates the female without copulation*
I have never feen the fecundation of the newt;
but my curioiity is much raifed: I beg you
will inform me in what this ftrangenefs con-
lifts ! My brain has long been difpofed, by
frequently taking cognizance of prodigies,
for the admiffion of the ftrangeft things , for
fuch furely is the reprodudion of the limb^
in the nevv t, which has engaged my attention
for fome years, and ftill engages it. I fliould
probably have {t^x\ the ad: of fecundation, if
I had kept individuals of different fexes in the
fame veffel: but my only aim was to obferve
with my 6wn eyes thefe beautiful organic re-
produdions.

LXXXIV,

LETTER i; 26s

Lxxxi\% Lxxxv. You treat in thefe ar-
ticles of the natural fecundation of the eggs
of the newt. I am totally unacquainted with
it, and fhould be obliged by a brief explana-
tion,

xcvi. What forejight do amphibious animals
jJoew in the multiplication of the Jpecies? No-
thing in the fludy of animals interefls my cu-
riolity fo much as their fore fight. We fre-
quently commit miftakes on this fubjeft,
and are apt to form very unphilofophical
ideas ; but of this I have faid enough in the
Contemplationy and elfewhere. We impute
to animals, with wonderful facility, our own
forefight and our reafoning faculty. Could
they judge concerning us, they would reduce
us to their ftandard; for they would attribute
to us their fenfations and adlions. Authors
. have run into the moft oppoiite extremes in
conlidering this topic ; I have fought the me-
dium, and hope that I have found it. You
have a good right to decide.

xcvii, xcviii, xcix. I find here fome-
thing relative to the induftry of animals, and
I dwell upon it with pleafure, having devot-
ed one whole chapter of the Contemplation to
the amours of the toad which you confider
hsre. You enquire. Why the male frog and

toad

z66 LETTER I» ^

foad emhr-ace the female fo clofely and fo long ?
I had prefumed, that fach a long continuance
had iome fecret final caufe -, but I was unac-
quainted with any obfervation which could
guide me to that caufe. I expect from your
friendfliip the infirudion which I want. I
ihould fofpecft, that the embraces tend to fa-
cilitate the defcent of the eggs or the tadpoles
into the du6ts, and thence into the uterus^
and moreover, perhaps to aid the expulfion
of the embryos. I meet in every part of
your fketch with enigmas, and hazard my
conje6tu re without hoping that it is the true
explanation.

c 1 1 . Has the interefting obfervation of Mr.
Demours, concerning the amours of the toad,
of which I made ufe, given occafion to any
critical refleClidn ? Was the obferver deceived ?
He certainly flood in a good fituation for ob-
fervin?.

cv, cvi. Here you do not feem inclined
to abide by the current accounts of the fecun-
dation of fcaly filhes. You fpeak of uncer^
taintieSy what are they? Do you doubt whe-
ther the male emits his milt upon the eggs ?
Or whether he repeatedly rubs the belly of
the female ? Or of both thefe accounts ? My
ov/n faith was very unfettled upon thefe
points. I could no where find deciiive obfei;^-

vations.

LETTER I. 267

vations. It is ailoniflnng fometimes to fee
Naturalifts remain fo long and fo contentedly
in doubt, about the moft interefting queftions,
and make no attempt to folve them by the
ealieft obfervations and experiments. The
mind, naturally fo adiive, is yet often very
indolent. To contrive an infignificant expe-
riment, or a fmall apparatus, requires as great
an effort as to undertake a journey. Such
obfervers only as you are always in breathy
fuch only have their minds aKvays in ad:ion
and forming combinations. You have m.ade
more difcoveries in five or fix years, than
whole Academies in half a century. I, how-
ever, v/ho know the labourer, and the rich-
nefs of the harveft, am not at all furprized.
When, in 1765, you obligingly alked my
opinion on the department of Natural Hif-
tory to which you fliould apply, I eafily fore-
faw how much that fcience would one day be
indebted to you. Your firft production on
the animalcules of infufions, fulfilled my pre-
diction, and your interefting letters upon the
wonderful reprodu&ons of the earth-worm,
the fnail, and the newt, were new confirma-
tions of it. I have contemplated, from the
filence -of my retreat, your gigantic progrefs
in that fine career.

CVIII.

268 LETTER I.

cviii. From this article I learn, that the
fecundation of the newt differs from that of
other animals ; but I am not informed in
what the difference confifts. The modifica-
tions of the great laws of Nature chiefly ex-
cite the attention of the philofophical Natu-
ralift. They ftrike him with the greater
force, as they fhew the endlefs variety of the
Creator's refources, and of thofe fubor-
dinate means, by which his Wisdom prepares
the firfi: developement of animated beings.
It was not confiftent with the oeconomy of
the world, that all generations fliould exift
together in a ftate of complete evolution.
The earth could neither have contained them,
nor fupplied them with food. They were^
therefore, placed one within another, in a
feries continually decreafing, and loft at laft
in the abyfs of infinite littlenefs. The ge-
nerations are therefore developed, one by
means of another, and their growth is pro-
portional to the order of degradations. Thus
they are gradually advancing out of impene-
trable darknefs, and at length arrive at the
term, which feparates the vifible from the
invifible, and from which, by the aid of fe-
cundation, they xnfenfibly arife to the degree
of perfedtion competent to the fpecies. But
'^ animated beings are greatly diverfified, fo

likewife

LETTER I. 2%

likewife are the laws which prefide over
their developement. Hence refult many va-
rieties in the forms which they facceffively
affume, and in the mode and effecfts of fe-
cundation. The deHneation of thefe phafes
and varieties, conflitutes the mofl engaging
part of the hiftory of generation.

cxxiii, cxxiv. From your numerous ex-
periments on artificial fecundation it appears,
that attempts of this kind upon germs, while
yet in the ovarium, or at the upper end of the
duels, will fail. I can, I think, affign the
reafon. The feed adls on thefe fetufes as a
iimple ftimulant. Now there is an original
relation between the latent power, which
caufes the irritability or the contradlion of the
mufcular fibre, and the prefent ftate of that
fibre. If it has not yet attained the necefi^ary
degree of confiftence, it will not be in pro-
portion to the mode of a(5tion of that power,
and its impreffion will therefore produce no
eifedl. The germ muft have arrived at a de-
terminate growth before it can be fufceptible
of irritation. Such was the reafonins: of the
great Haller.

cxxviii, cxxix. I find here a particular
which embarraffes me. Artificial fecunda-
tion y you fay, does not fucceed in the newt with
pure feed^ and it is necejfary to dilute it with

water.

2)0 LETTER I.

water. But pure feed is the efficient caufe of
natural fecundation : how then comes it to
fail' in the artificial ? does the air infpiffate it
too much, or is it mixed with fome thinner
fluid at the inftant of its emiffion from the
male. I know not what to think. You will
inftru(5l m.e.

c X XX I V . T^he feed does not lofe its prolific vir^
tue^ though incorporated with other liquors. I
have great pleafare, rny dear philofopher, in
feeing you found Nature, by means of com-
binations which ihe never made. Preceding
phyfiologiils did not conceive the idea of fuch
combinations. But what liquors did you
mix-with the femen ? it does not, it feems,,
mix intimately with them- ; there |s no che-
mical folution, fmce the fperm r^ains its
prolific virtue-— it is at leaft very certain,
that it is not decompofed by thei^ifFereifi?*'
liquors, for decompofition w^ould deftroy its
ftimulating power. How do ypureafon on
thefe ficts ?

ciLiii. ^hree grains of feed incorporated
'with eighteen ounces 0/ water, retain perfedfly
their jecundatmg virtue in the green aquatic
and in the tree- frog. Ihree graiijs diluted with
two hundred and fixty four ounces of water, do
not altogether lofe their efficacy. This would
never have been fufpeded; v/hat Vv^onderful

energy

LETTER I. 271

energy muft this fingular fiimulant poffefs !
fince it is not lenfibly weakened, when three
grains are mixed with eighteen ounces of
water, and is even perceptible, when they are
dikited in two hundred and lixty-four ounces !
thefe three grains of feed apparently are diffufed
through this body of water, as three grains
of mufk are diffufed throueh the air of a
large appartment^ they neverthelefs a(fl upon
the fmell, and irritate, the nervous fibres;
this irritation illuflrates the effe^l; produced
by feed diluted in a lai*ge quantity of water,
upon the mufcular fibres oft the heart of the
eml^^o.

ex^^y, cxLv. Other remarkable expert"
jjtents uppn a little feedy mixed with a great
quantity of water. Experiments fo nev/ and
inftrudtive, could not be too much varied ;
. and it is with great fatisfaclion I obferve, that
you have taken advantage of Nature's com-
^laifence. I beg you will give me further in-
ftrudiion on this head.

CLii. 'Th£ feed fecundates tadpoles by pene-
t rating into their diminutive bodies. Small
openings for its admiJjto7i. Such circum fiances
have always been more interefting to me,
than any thing in the hiftory of fecundation.
I have, always, you know, prefumed that
fecundation was effected jrora without -, and

vou

•2T2

you may recolledl, that I once defired you
to fearch for the Uttle pores, which I ima-
gined Nature had wrought in the covers of
the germ, for the introdudion of the feed :
You have now difcovered them, and I congra-
tulate you moft fincerely. The difcovery is
of high importance, and I am quite impa-
tient for the particulars, I have obferved in
a new note. Chap. x. part. 7. of the Con--
templationy '' What happens openly during
the fecundation of the eggs of amphibious
animals, takes places in other clafTes in the
obfcurity of the ovarium. The egg is al-
ways fecundated externally, both in ovipa-
rous and viviparous animals. The fuppofi-
tion followed very naturally, after the em-
bryo was allowed to exift entire in the egg :
the obvious inference was, that the feed
acfled only as a nutritious and ftimulating
principle. But this limple and philofophical
notion of fecundation could not be conceived
by thofe who rejedl all organic preformation,
and imagine, that the embryo is mechanically
formed by certain pov/ers of affinity (forces
de rapport) or by the fucceffive juxta-pofiticn
of certain molecules iffuing from the male and
female, which had been moulded within
them.

CLVIII.

LETTER I. 273

C L V 1 1 1 . . Whether the fmall portion of fee d^
employed by Nature for the impreg?7atio?2 of am-
phibious animals, affords reafon to juppofe that
large animals alfo are iwpregnated by fo i?iconfi-
derable a quantity. I am very defirous of
knowing your thoughts on a fubjcd:, which
has never been properly dilculied, becaufe,
before it could be properly difcuffed, it was
necellary to make thofe fine experiments,
which you have fo well executed on amphi-
bious animals, and which yet were not fup-
pofed to be poilible. If the ovaria of an
ev/e, bitch or cow, could be laid -bare vvith-
out endangering life, your queftion might be
decided by experiments like thofe on amphi-»
bious animals, which fuggefted to you fo
many new truths. You might touch with the
end of a pencil, dipped in the feed of tne
male, one or more of the vejiciilce of the ova-
rium ; and if the w^ound could be healed
without deflroying the effect of fecundation,
you W'Ould find the quantity- of feed neceifary
for this purpofe in large animals. This fin-
gular experiment would perhaps fucceed bet-
ter on the greater oviparous fpecies. If it is
to fjcceed at all, it m.uft be in your hands.
You have accuiiomed me to expect much
from your dexterity and perfeverance. Should
you only be fortunate enough to perceive an
Vol. II. T incipient

274 LETTER L

incipient evolution of the germ, it would be
fufficient for our inftrudion. There are ob-
fervations which directly prove, that the fe-
tus may be developed in the ovarium. You
might alfo try to injed: different quantities
into the matrix. Should the fm.alleft portion
prove as efficacious as the greateft, it would
become very probable, that the fecundation
of large animals differs but little in this re-
fpect from the amphibious clafs.

CLix. The feed of amphibious animals feeim
to be afimple ftimulant^ and not a nutritious
jiuid. I think I perceive the foundation of
vour conclufion. You cannot reconcile the
fmall quantity of feed fufficient for fecunda-
tion, with the idea of a fluid, deftined to fup-
ply all the parts of the embryo with their firft
nutriment. You calculate (clv), that the
bulk of this portion of feed, is to that of the
embryo, as i to 1064777777. There can,
therefore, be no fort of proportion between
the nutritious fluid, and the embryo to be
nourifhed. I fliall not conteft the juflinefs of
your inference, as far as it regards amphibi-
ous animals; but I do not think you can ex-
tend it to large animals. The mules pro-
duced by them furnifli fads, which render it
impoiPible to doubt, that the feed modifies
various parts of the embryo: I have given

feveral

LETTER I. 275

feveral Inftances^ the feed is therefore carried
to thefe parts, and how can it be imagined
to change their forms and proportions without
penetrating into them [a]? Confider, in par-
ticular, the larynx of the great mule, I am
brief^ but you, who underftand my principles
as well as I do myfelf, will eafily comprehend
my meaning.

c L X V 1 1 . 'The feed is 7iof a fpirifnous nor 'very
'volatile liquor ^ as J ome philojcphers have imagin"
ed, I am glad you have afcertained this^ but
after having iliewn what the feed is not, have
you difcovered what it is ? We well know,
that it is one of the moft highly wrought
fluids in the animal body. Have you made
any chemical experiments upon it ? I have

(«) When the experiments related in this work, Hiall be
attempted upon large animals, as there is every reafon to hope
that they foon will, with fuccefs, I do not think there is any
';^ eat temerity in prediding, that this favourite hypothecs of
Mr. Bonnet will be proved to be falfe. It was long fince re-
jeded by Haller, the moH candid and acute examiner of phy-
fiological hypothefes ; and Spallanzani has furnifhed a very
powerful additional argument, derived inde*i from analogy,
but more cogent than any proof in favour of it. There arc
numberlefs examples, of parts of the fyftem being deeply af-
fefted by fubftances not in contad with them. Nervous fym-
pathy is called in to explain fuch phenomena, and to what
elfe is it poffible to impute them? Phyiiologilts will, in like
manner, I fuppofe, deduce the changes produced by the feed
of one fpecies upon the embryo of another, from the fame
caufe, T.

T 2 always

2^6 L E T T fe R I.

always entertained a fufpicion, that it very
much refembles the nervous fluid. I have
proved, that irritability muft depend on a
very active fluid, diileminated among the
mufcular fibres. Contemp-^ Part X. Ch, 33,
The feed of amphibious animals, which may
have a certain affinity (rapport) with the
fluid difperfed in the fibres of this impelling
organ. Here we find depths that cannot yet
be fathomed.

CI.XVI11, The eleBric fluid accelerates the
evolutio?! of fecundated tadpoles, but does not
ajiimate thofe which are impregnated, I thank
you for having tried, as I propofed, v^hether
the elsdric fluid might be fubfl:ituted infl:ead
of the feminal liquor, in the artificial fecun-
dation of tadpoles. It did not anfwer, and
you may imagine, that I do not wonder at
the failure. It vi^as proper to make the trial.
^e fait on i^ a queftion that frequently re-
curs in natural philofophy and natural hif-
toryj You have at leaft found, that the
eledrical fluid forwards the evolution of fe-
cundated tadpoles, a new obfervation, to be
added to thofe recorded in the hifl:ory of elec-
tricity.

CLxix, CLxx. Various other liquors are
incapabk of effeciing artificial impregnation.
That talent of combination which you pof-

lefs.

LETTER i: 277

fefs, and which charadizes the true natural-
ift, gave me reafon to expedl thefe various
experiments. Nature, by her negative re-
fponfes, has afforded you no lefs information,
than when fhe has anfwered in the affirma-
tive.,

CLxxi. The feed of the newt is incapahle of
fecundating the embryos of frogs and toads ^ and
reciprocally This is alfo true of the feed of
toads and frogs refpeBing one another. Thus
though Nature produces mules between large
animals, and even between infed:s and plants,
fhe refufes them to the amphibious tribe.
You very properly queftioned her on a fubjed:
fo important; from her anfwers we learn,
that fhe has not here allowed herfelf any la-
titude. This is very remarkable 5 for at firfl
fight, the toad appears to differ much lefs
from the frog, than the horfe from the afs.
If the contrary had happened, and you had
obtained mules by the artificial impregnation
of amphibious animals, you would not have
had fuch good reafon for concluding, that
the feed of thefe animals a6ls but as a ftimu-
lant. It would remain to inquire, why Na-
ture has here fet herfelf fuch narrow limits.
If it fhould be faid, that in fpecies appirently-
fo nearly allied, one degree more of approxi-
mation would have deflroyed the fpecificcha-

T 3 rattier.

278 LETTER I.

rafter, this would be to affign the final, but
not the efficient caufe.

CLxxii. The eggs of the wifiged infeB pro-
duced from thejllk worm^ artificially fecundated
by the author. An Italian, the famous Mal-
phigi, firft imagined this experiment : ano-
ther Italian, the fecond Malphigi, firft fiic-
ceeded in it. Above eighteen years ago, I
exhorted naturalifts to repeat this interefting
experiment; and in this long interval, the
philofopher of Reggio alone has undertaken
it. What fatisfaftion muft he receive on
this account ! But he v^ill not confine himfelf
to the eggs of this fpecies ; he v^ill proceed
to thofe of other phalaenas. He v^ill try to
fecundate the eggs of one fpecies with the
feed of another : he will defire to know,
whether butterflies and moths refemble am-
phibious animals in this refpedl ; and he will
not, I am fare, negled: making the fame
trials upon other different infedls. Rea-
foning will not illuftrate this fubjedl : ex-
periment alone can fupply the information we
defire.

From all your experiments, you deduce a
conclufion highly pleafing to me ; all the
dreams of modern epigenefifts are difowned.
by Nature. You know how averfe 1 have
been all my life to this fyftem 5 I have com-
bated

LETTER I. 279

bated it in all my writings, and when my late
illuftrious friend Haller was inclining to
this hypothefis, I had the courage to refift
him, notvvithftanding the impreffion his au-
thority made on me. The chicken came to
my affiftance, and the great phyfiologift de-
clared againft epigenefis.

I have gone through the principal articles
of your table : many things are left behind,
but the revifal of my w^orks does not per-
mit me to attend to you as much as I could
wiih. I pafs to your kind letter of the thir-
teenth of March, which I have not yet an-
fwered.

I knew not that the celebrated Merian had
obferved the Pipa before Ruyfch. I have
made ufe of the pafiage from that heroine,
which you obligingly tranfcribed for me (a).
I have inferted it in an addition to my Me-'
moir. I have made the fame ufe of that
from Vallifneri, which was alfo quite un-

{a) In a letter, written March 13, 1780, to Mr. Bonnet,
about his Memoir on the Pipa, inferted in Rozier's Journal
for 1779, and of which I fpeak incidentally in Se(5^, crv, I
informed him that Merian, and not Ruyfch, as he fuppofed,
firft fpoke of this fingular animal ; and I moreover communi-
cated to him the erroneous opinions of Vallifneri, who affirm-
ed, that the kind of uterus containing the young toads, is upon
the back of the male, and not of the female. To this para-
graph of my letter Mr. Bonnet alludes.

' T 4 known

2 So LETTER I.

known to me. Your cenfure of his negli-
gence, in not afcertaining the fex of his two
pipas, is juft. I have difledled, or rather
flead the pipa left in our bottle ; but the fa-
tigue my eyes underwent, together with the
quantity of fpirits which had penetrated into
the infide, hindered me from obferving dif-
tindtly every thing that lay before me. I
made my incifion on the belly, and after turn-
ing aiide the fkin, perceived the mufcles and
internal teguments. Having removed them,
I difcovered the inteflines. I was firft ftruck
by a number of bright yellow grains that
were difperfed over the vifcera. In order to
learn whether their fhape was regular, I ob-
ferved them with a glafs, but it appeared to
vary a good deal ; fome being round, others
oblong, and others again like quadrilateral
plates. The ftomach was oval, mufcular,
and thick; it was filled with many fmall
brown fragments, very brittle, fome a line
or tv/o in length, and pretty much refem-
bling fragments of the leaves of plants. —
But to come to our chief object, I could not
perceive any veftige of an ovarium; I fought
for the tefticles, and found, near the bladder,
an oblong flefhy body, which might perhaps
be a tefticle, but I could not find that on the
ler fide. I could not^ indeed, perform

this

LETTER I. 281

this diffedion according to my wiflies ; I faw
juft enough to form an idea of the great ap-
paratus of vifcera, which this lingular toad
offers to the attention of the obferver ; every
one of which might employ him whole
months, if he had the inclination or the abi-
lity to ftudy it as Lyonet ftudied his eruca.
To refute Vallifneri's opinion, it is not abfo-
lutely neceffary to have recourfe to diifedlion.
Mr. Fermin's obfervation, of which I have
given the fubftance. Sect, cccxxvii. Corps
organ, n, i. leaves no room to doubt that the
female's back is furnilhed with the cells,
jQnce he diflecled her, faw the ovarium, and
was an eye-witnefs of the union of the fexes.
I am glad my Memoir afforded you fatisfadtion .
I wifli the queftions at the conclufion may
induce fome Naturalift to examine more par-
ticularly an animal fo remarkable, and as yet
without parallel.

I thank you for the Italian extrad: from
your refearches on the movement of the
blood, which I could not read in your excel-
lent work. Mr. Saladin tranllated it, and I
fhall borrow from it fome curious particulars
for a note on Part x. of the Contemplation.
I afk nothing further on this fubjedt, for my
editors prefs me to finifh as foon as poffible.
The fubfcribers grow impatient, and threaten

282 LETTER. 1.

to withdraw their contributions. I have
been obHged to write a fliort letter in ex-
cufe of my involuntary delay, and to fatis-
fy them about the delivery of the fubfequent
parts.

Your conclulions, relative to the blood,
have entertained me highly. You firft have
difcovered an important truth; the impulfe
given by the heart is perceptible to the com-
mencement of the veins. That the motion
of the blood does not, as phyfiologifts fup-
pofed, become flower at the extremities, of
the arteries, is another new obfervation of
equal importance. They were miftaken
about the power or powers of circulation.
They affigned to the heart auxiliary forces ;
and you have (hewn, that the heart is the fole
impelling power. You have alfo proved, by
an ingenious contrivance, that the changes of
the colour of the blood, from yellow to red-
diih, and then to red, are mere illuiive ap-
pearances. Hailer warmly contefted this
point, but your mode of proceeding, I think,
carries convidion. The vafcular membrane,
feparated from the yolk of the egg, and ob-
ferved upon a plate of glafs, exhibits red
veffels on the firft days of incubation. You
almoft every where deftroy error, and efta-

blifli

LETTER I. 283

blifh truth. I moft fincerely bid you fare-
well. You fay nothing of the fecundation
of plants : I have not been able to repeat your
experiments this year.

END OF LETTER I,

LET-

[ 2^4 3

LETTER II.

i

Genthod, January 13, 1781.

T PERCEIVE by your interefting replv,
•*- my dear and celebrated friend, that our
opinions on feveral points coincide^ this co-
incidence affords me the greater pleafure^ be-
caufe it fhews, that I have rcafoned juftly on
feveral of your experiments. Butfuch a co-
incidence is no new thing between you and
me, for how often have we converged in Hke
manner on feveral topics of Natural Hiftory?
It maybe faid, that my foul fometimes paifes
into your brain, and your's into mine. I owe
you many acknowledgements for having in-
terrupted the compofition of your work on
the generation of plants, in order to write
that long and excellent letter, which you call
upon me to anfwer. I am furprifed that you
have been able to do it in two days. I am
not fo happy as you in this refped:, being able
to allot a few hours only in a day to compo-
fition, fo that when I write letters of eighteen
or twenty pages, you may be fure that they
have taken up at leaft twelve days. I muft
therefore now, in my turn, fufpend my own
labours, for the fake of anfwering the prin-
cipal

LETTER II. 285

cipal paiTages of your letter of the 12th of
December. I ihall follow the order of your
numbers, or rather of my own in my laft letter,
which you yourfelf followed, and to which
you replied.

I. I doubted not but the experiments which
I propofed tc you, in order to detedl the
germ in the ovarium before fecundation,
would likewife fuggeft themfelves to your
confideratiou {a). You feem not to expect

much

{a) In order to elucidate this paragraph, I ihall tranfcribe
the pafTage of my letter to which it refers. Mr. Bonnet, in
his firil letter, cbferved, that fearching for the embryo in the
ovaria of quadrupeds and birds, before the accefs of the male,
would certainly illi itrate Natural Hiftory : He was of opinion,
that I might make fome advances in this dark enquiry. I re-
ply, '* That the idea of turning my attention towards the
ovaria of quadrupeds and birds, had often arifen in my mind ;
but that I had never enjoyed fufficient leifure to put it in prac-
tice. The urgency with which you recommend thofe refearches,
is a powerful incentive to me to attempt them, and perhaps I
may do this ere long ; but I confefs that my expeftations are
not very fanguine. 1 fear, left the extreme minutenefs and
tranlparency of the germ ihould prevent me from difcerning it.
It is, hcwever, better to undertake unpromiling experiments
on a fubjcd: fo intereiUng, than to leave them unattempted.

** Having lately had occalion to read fome of Reaumur's
memoirs on infefts, I met with an obfervation of an Italian
Naturaiift, very analogous to mine, upon the prc-exiftence of
the tetufes of the frog and toad. It is in Vol. III. P. i.
Mem= 7. Reaumur, fpeaking of the caterpillar of the little
beetle (Jcarahdeus) of the lily, after the fine diffenation of
Patarol, fays, '* Mr. Patarol thinks, that the grubs cannot
be fajd tp come from the eggs, but that every ^%i appears to

be

2 86 LETTER II.

much from them : You prefume that the ex-
treme minutenefs, as well as the tranfparency
of the germ, would conceal it from all your
lefearches. You do not however defpair;
and you give me room to fuppofe, that my
exhortations contribute to encourage you :
but the great fuccefs which has crowned your
refearches on other occafions, might ferve to
perfuade you much more powerfully, that
you will not on the prefent labour in vain. A
lucky accident, fome unexpected and unfore-
feen circumftance, may afford you the greateft
affiftance. You will create fuch fortunate
occurrences as do not happen in the ordinary
courfe of Nature, and as will furprize you
with a full view of that which Nature con-
cealed from Malphigi and Haller. It feems
to me, that the firft ftep neceifary is to find
the means of diminifhing the tranfparency of
the germ without altering its ilrucflure ; for
in my opinion this, rather than its extreme
minutenefs, keeps it concealed from the mofl

be changed into a caterpillar. The reafon that induced him
to propofe fo lingular a notion, was, becaufe he could not find,
with whatever care he examined, any empty fliell." Obferve,
I beg of you, the conclufion of the French Pliny ; he appears
defirous of repeating the obfervation, though other occupations
prevented him, it would feem, from executing his intention.
I am refolved to repeat it next fpring, and I think Reaumur
did QOt fet a fujHicient value upon it.'*

piercing

LETTER II. 287

piercing looks of the obferver. A drop of
vinegar, or fpirit of nitre, poured on the
cicatricula of the egg, by a little condenfing
the moifture which dilutes the folids of the
germ, may perhaps render them perceptible.
You might alfo try other liquors. Two other
means fuggefl themfelves to my mind : The
iirft confifts in endeavouring to fpread a liquor
coloured by fome vegetable tin^flure over the
yolk : how do we know but the veffels of the
yolk would abforb this tindlure, and carry it
to the germ ? Should it only colour the con-
tiguous parts, it would at leaft fhew its place
or point. The aftion of the veffels fhould be
aided by a gentle heat. The ingenious pro-
cefs employed by Mr. Beguelin, to fhew the
Prince Royal of Pruffia, the fucceffive pro-
grefs of the chicken in the egg, would not
be unferviceable to you in your attempts.
Again, who knows but a certain degree of
heat would contribute to render the germ ap-
parent, by coagulating its lymph ? To fub-
ftitute the femen of the cock, or any other
bird, would be another means of attaining
the fame end. As the femen is, beyond
controverfy, the liquor which has the great-
eft influence upon the germ, it feems to be
befl adapted to produce fome ilidden change,

fuch

268 t E T T E R 11.

fuch as might render it acceffible to the mi-
crofcope.

It would be, at the fame time, an attempt
to produce the artificial impregnation of the
germ in the egg. Mr. Beguelin's apparatus
would be very convenient for this purpofe.
Should a drop of feed render the embryo im-
mediately perceptible, it could not be objedl-
ed that the feed had conveyed it into the cica-
iricula^ as it has been fuppofed that \ht farina
fecundans does the plant into the grain ; for
Haller's obfervation, as vi^ell as your difco-
very of the exiftence of the tadpole before
fecundation, would deftroy the objection .
Laftly, it would be proper to try to obferve
the cicatricula of unimpregnated eggs in the
folar microfcope, v/hich enlarges objedts
which are in fome meafure tranfparent more
than any other. Need I add, that you will
not be feeking for fomething which does not
exift, lince you have the ftrongeft reafons to
fuppofe, that the germ does really exift in the
cicatricula.

Curious experiments have fliewn, that the
perfpiration of the egg, notwithftanding its
cruftaceous cover, is confiderable. Various
internal changes proceed from this. You
will therefore obferve the cicatricula in unim-
pregnated eggs kept for a longer or fhorter

time.

LETTER it; 289

time. Perhaps drying the cicatricida a little
upon a plate of glafs, before it is obferved by
the micro fcope, may be of ufe. The ap-
proximation of the elements of the folids,
may fomewhat lelTen the tranfparency of the
germ.

It will be proper, my dear Malpighi, to
obferve the real or fuppofed eggs of the beetle
of the lily. The pallage you have quoted
from my illuftrious mailer fhews clearly, that
he faw the neceffity of repeating Patarol's
obfervation. It is^ to be regretted that he
did not do it, or at leafl inform us whether he
had or not; but we may reafonably doubt,
whether this illuftrious Naturalift imputed
to this obfervation the fame degree of im-
portance as you and I. He had not meditat-
ed fo much upon generation, and particularly
upon the interefting queftion of the pre-ex-
iftence of the germ. You may eafily fup-
pofe, that I fliall not be much furprifed if
you fhould one day infol*m me, that the fup-
pofed eggs of this beautiful little infedl are
not really eggs, but the caterpillar difguifed
under the appearance of an egg. If fo,
thefe imaginary eggs v/ould agree with thofe
of frogs, and we ihould have anew proof of
the pre-exiftence in queftion. You are ac-
quainted with the eggs of the queen bee ; I
. Vol. II. U have

2gO 1 E T T E R II*

have fome fufpicion, that they are not real
eggs, but the maggot itfelf, in a ihape httle
different from that v/hich it aifumes after fe-
cundation. But the vivaparous flies, of
which Reaumur has written the curious hif-
tory in voL iv, will furely afford new proofs
of the pre-exiilence of the embryo in the fe-
male. The fpiral matrix, defcribed by the
author, is a beautiful organ ; the different
convolutions he informs us, conlift of more
than 20,000 maggots, arranged lengthways
by the fide of each other.

XIII. I am obliged to MeiTrs. de Reaumur
and Nollet, for thofe little breeches of waxed
taffety, which they contrived for the male of
a certain fpecies of the frog, in order to dif-
cover the manner in which he impregnates
the female, and 1 am not lefs obliged to you
for the repetition of this ingenious experi-
ment. The male, which you cloathed with
thefe breeches, did not accompliih the im-
pregnation of the female, becaufe the femen
was intercepted. Since this liquor impreg-
nated artificially the tadpoles to which you
applied it, there can be no doubt but that it
was real femen.

XXVI. You are then of opinion, that the
fufpicion I intimated in this article is not
without foundation. I learn from this para-
graph

L E T t £ R lU 29I

graph of your letter a new truth, *^ that in
the TREE-FROG, the tad- poles are fome*
times found fecundated, though they remain
as yet in the recflum ; whether this happens
in confequence of the femen infinuating it-
felf into the orifice of that inteftine, or be-
caufe the tadpoles, fcarce out of 'the redlum,
and already moiftened by the femen, are per-
haps drawn into it by the motions of the fe-
male at the inftant fhe is furprized by the ob^
ferver.'* Both thefe explanations appear
much more probable than mine*

Lxxv, Lxxvi. I am always a great gainer,
when, according to your wiihes, I point out
to you new experiments to make. You have
then made upon the fecundated eggs of fifhes
that which I propofed, (Art. 418. Corps
organ.) : in order to afcertain, whether thefe
eggs might be kept in the dry, like thofe of
the tufted polypus ^ and you have found, that
they do not poffefs this privilege. Your va-
rious ways of proceeding, permit me not to
doubt of the truth of the refult. You have
carried this experiment ftill farther to the fe-
cundated embryos of frogs and toads, and
you have found, that they do not, any more
than the eggs of fifhes, poiTefs the property
of keeping in the dry. My hypothefis then,
with refpefb to the repeopling of d^ied ponds,

U 2 is

2gZ LETTER II*

is Infupportable : but may not this privilege,
which has been refufed to the eggs of fiihes,
have been granted to fifties themfelves in the
ilate of infancy, or at fome other period of
their hfe. I am very defirous of knowing
the conjedlureyoufubftitute inftead of mine,
and which you intend to explain in your
work. Reading this paiTage over again, I
perceive a circumflance that had efcaped me ;
you fay, *^ that you left your fifties eggs to
dry in the fliade, fometimes on the mudy where
you found them, and fometimes in vefi^els/*
But may not the fecundated eggs of fifties re-
quire, like the Rotifer ^ to be covered with
fand, in order to be preferved in the dry ? I
can fcarce fuppofe, that you neglected cover-
ing them with the mud on which they were
laid by the female, well knowing, that in
your experiments you negled: nothing [a).

Lxxx. Your account of the Angular man-,
ner in v/hich the male newt impregnates the
female has afforded me great pleafure; the
whole was entirely new to me. The newt

{a) Mr. Bonnet's opinion of me is too favourable ; for in
truth I was not aware of this precaution. But were it employ-
ed, I do not think it very probable, that the eggs of fifhes,
and the fetufes of frogs and toads could be preferved. The
thing 13 however poffible, and the experiment ought to be re-
peated with this circumftance, which I propofe to do when I
have an opportunity.

is

LETTER II, 293

is then very chafte in his amours; no true
copulation takes place between the two indi-
viduals ; only a few carefles on the part of the
male, which prepare the female fur fecunda-
tion. The male darts his femen into the
water; it forms a little whitifli cloud, which
furrounds the open and fwoln anus of the
female, and fhe is fecundated. What pity,
that the poets were unacquainted with the
chafte amours of this animal — their fidions
w^ould have derived great advantage from the
hiflory. That of Zephyr and Flora bears a
ftrong analogy to the fecundation of the
palm; in the animal kingdom, I know no-
thing which refernbles it more than the im-
pregnation of the newt. That of marine
plants approaches ftill nearer, the male does
not emit a fine powder, but a liquor, which,
in like manner, forms a flight cloud in the
water.

Your citation of Bomare's Diftionary, has
induced me to read the article Newt^ which
I had never before confulted. Mr. Demours,
I fee, feems to have made the fame obferva-
tions as you, refpedling the fmgular mode of
impregnation in this animal. But naturalifls.
will rely more upon you, and it required to
be verified by an obferver of your eminence =
Du Fay's remark alfo concerning the prefence

U3 . of

294 X. E T T E R II.

of the gills, when newts are young, and
their difappearing totally afterwards, drew
my attention. I had obferved the fame thing
with furprize, but never mentioned it, for I
was defirous of obferving it again, but never
did, Thefe gills are a great ornament to the
young newt. Du Fay was aware of the or-
ganization of the epidermis, mentioned in
jny firft Memoir; and if I had been acquaint-
ed with the pafl'age of this academician, I
would have taken notice of it.

Since the femen of the male is always
mixed with water, I fee the reafon why ar-
tificial fecundation does not fucceed with
piire fe?ne?i. The obferver muft imitate na--
ture and dilute it with v/ater. I fuppofe
with you, that the very thick feed of the
newt requires dilution, in order to effed:
both natural and artificial fecundation. In
like manner, the wifdom of Nature ha§
found the means of diluting the human femen
by the lymph, which fo many veffels pour
into the tefticles and the feminal veficles,
Phyfiologifls tell us wonderful things on this
fubjed:,

Few fpedlacles areJo engaging to the philo-

fophic obferver, as that prefented by the

amours of animals, and the various means by

which the Author of Nature ha3 ordained

' ^ that

LETTER ir: 293

that they fhould preferve their fpecies.
Should Ibme able phyiiologifl ever undertake
to compofe a complete hiflory of generation,
he would undoubtedly begin by a delineation
of the amours of animals and plants; and if
he fhould be as great painter as the illuftrious
JBuifon, he will be able to engage the under-
ftanding, without giving any alarm to mo-
defty ; he will produce, not 2iphyfical Venus [a) .
but a phyfical Minerva. There is room
for fuppofmg, that the different modes of
fecundation, obfervable in different animals,
are proportional to the degree of fenfation
accorded to each fpecies, or what amounts
to the fame thing, to their capacity for en-
joyment. What difference in this refped:
between the fifh or newt, and the ape, the
ilag, or dog ; and in the imperial race of
man, how is the phyfical part modified by the ,
moral !

It is certainly very remarkable, that am-
phibious animals, fuch as toads and the tree-
frog, never depofit their embryos on dry
ground, where they muft infallibly perifh,
and that they always take care to depofit
them in water, their natural element. You
gven give me to underfland, that they do not

U4 lay

{a) Venus Thyftfie, the title of a book written by M. Ma^-
pertuiso T«

2g6 L '^ E T T E R II.

lay them in the firft water they find, that
they never make the difcharge in running
waters, which would carry the young away,
and not fupply them with proper food ; but
that they confliantly depofite them in ftagnant
waters, where the Uttle tadpoles are not ex-
pofed to concuffion, and where they are al-
ways furrounded by proper food. This
kind of inftind: very nearly imitates forefight,
and attains its end equally well. But fmce
we cannot, in this cafe, admit real forefight,
which belongs exclufively to reafon or intel-
ligence, it remains to be afcertained, how
our amphibious animals are fo unerringly de-
termined to quit the ground, for the fake of
laying their eggs in dormant v/aters. The
female, I fhould imagine, preiTed by the de^
lire of laymg, mufh feel a certain internal
fenfation, which renders her abode on dry
ground painful, and infpires her with the"
defire of gaining the water; and fince ftag-
nant waters are not fo cold as running waters,
this may, perhaps, be the reafon why fhe
prefers the former, not for the fake of her
young, of which fhe cannot have any know-
ledge, or forefee the wants : for it is thus
that Nature hath, on all occaiions, provided
for the neceffities of young animals ; fhe has
found means to conned: their wants with

thofe

LETTER II. 297

thofe which the parents themfelves feel in
certain circumflances. Your memory muft
fuggeft lb many inftances, as to render it un-
neceffary for me to point them out. Befides
I fee you entirely agree with me, with re-
fpevfl to the forelight and intelligence, fo gra-
tuitoully, and fo unphilofophically attributed
to brutes.

xcvii, xcviii, xcix. I knew not, that
your illuftrious compatriot Vallifneri had en-
tertained the fame idea as myfelf, concerning
the effedt of the long continued embraces of
male frogs and toads. Nor did I recollect
that Swammerdam, on the contrary, had
fuppofed, that fo far from facilitating the
paffage of the eggs into the tubes, they ra-
ther ferve to hinder it. I fhould not then
have known, which fide to have taken be-
tween thefe tv/o great authorities, if Nature
herfelf had not pronounced her decifion from
your lips. You inform me, that the opinion
of Swammerdam, that the females are not
embraced by the males, until the eggs have
already traverfed the tubes, is not generally
true ; that it holds only in the tree-frog^ and
by no means in the aquatic frog and in tqads,
but that Vallifneri is right with refpect to
the green aquatic frog. In this cafe then,
no general rule can be eftabliilied, as you

very

2o8 LETTER n;

very properly remark, and we muft wait till
new refearclies have increafed the number of
fads. • ,

CI I. Mr. Demours had raifed our curiofity
to a very high pitch, by his account of the
addrefs of the male toad in affifling the fe-
Hiale in bringing forth. His details were fo
circumftantial, that the truth of the fad: ap-
peared to be unqueftionable, and I hefitated
not to make ufe of it in the Contemplation^
But it is really very fingular, that neither
you, my worthy friend, nor Mr. Roefel,
ihould have furprifed any male toad in this in-
terefting employment. This would appear
to weaken the credit due to the recital of the
French obferver, if tefiiimonies limply nega-
tive could impair the moft pofitive affirma-
tion. Mr. Demours ought, as you obferve,
to have fo defcribed his toad, that we might
have knov/n to what fpecies it belonged.

cv, cvio Your doubts, withrefped to the
manner in which the impregnation of fcaly
fifli is effected, are well founded, and we
have both reafoned properly upon this fubjed:,
by eflimating the authorities on either fide.
We know at leail, from the experiment of
Mr. Jacobi, that fimple difperfion in water is
fufficient for the impregnation of the eggs.
Your idea of employing the Chinefe gold

LETTER II. 299

fiflies to clear up the queftion, to me appears
excellent, and I cannot prefs you too v/armly
to realize it.

You will fee much more in one day, than
all preceding naturalifts have ever obferved.
How many interefting queftions yet undeter-
mined, might be decided by the mcfl fimple
experiments ? The mind has always a greater
tendency to imagine and reafon, than to ob-
ferve and make experiments. To what a
train of reafoning had Digeftion given rife,
before Reaumur and Spallanzani fet this func-
tion in the cleareft light by their fine experi-
ments.

c XXI 1 1, cxxiv. You adopt then with me
the Hallerian docftrine of embryos lodged in
the ovarium, or in the upper part of the
tubes of our amphibia, which cannot be fe-
cundated artificially. But you affign another
caufe of the fad:, which I did not fufped:,
but which appears to me, not lefs than to
you, to contribute to produce it; fince the
glairy matter is the firft nutriment of the fe-
cundated embryo, and fince this matter does
not envelop thofe contained in the ovarium, or
the upper part of the tubes, it is evident,
that even if the femen could impregnate
them artificially, they would foon periih for
want of nouriihment. Your experiments on

this

300 LETTER li;

this fubjed leave nothing to be wilhed, fince
the embryos you have entirely ftripped of
their gluten could never be impregnated,
while thofe which were only partially deprived
of it, were almoft all fecundated. I know
not whether naturalifts before you, were
acquainted with the true ufe of this matter.

cxxxiv. The blood of amphibious ani-
mals, their faliva, the juice extracted from
their liver, lungs, kidneys, their urine and
ours, are then the different liquors with
which vou have conceived the idea of mixing
the femen. To thefe you have added vinegar,
and none of the mixtures have deprived the
femen of its prolific virtue. You have only
obferved, that when the urine and the vine-
gar were in too great abundance, fecundation ■
did not take place ; I doubted not but that
you would think with me, that the femen is
not decompofed by thefe mixtures. But they
admirably prove the aftonifliing energy of
this fecundating liquor. They may further
ferve to guide you to difcover, which of the
animal liquors has the greateft analogy with
the femen : for that, which in equal quanti-
ty fhould leaft: impair the virtue of the femen,
might juftly be prefumed to be moft analogous
to iti and this would not be without its ufe,

in

LETTER !!• gOl

in Inquiries into the conftituent parts of the
femen.

cxLiii. It affords me great pleafure to find,
that we have both had recourfe to the fame
comparifon, in order to illuftrate the proHfic
power of femen incorporated in very fmall
quantity, with a very large mafs of water.
Your example, taken from the poifon of a
viper, of which a very little drop often proves
fatal to a great animal, is not either lefs ap-
propriated or lefs inftrucftive. Hence you
have good reafon for faying, that we cannot
be furprifed, that a very fmall portion of femen
fhould be fufficient to animate the heart of the
embryo.

The very fudden adion of certain poifons,
fuch as the venom of the viper, afford
room for prefuming, that it is chiefly the
nervous fluid that is affedled. You rem. em-
ber Reaumur s curious experiments with
American poifoned arrows. A bear pricked
with one of them died, I think, in half a
minute.

cxLiv, cxLv. In this article, you farnidi
me with a detail of the manner in which you
have proceeded in your artificial fecundations.
I entirely approve of it. It is furely very
furprifing, that an embryo touched with the
point of a needle, which has been dipped m a

mixture

^02 t ^ T t £ ft It;

mixture of three drops of femen, and eigh-
teen ounces of water, and which takes up a
drop, meafuring i-5oth of a hne, fhould have
been developed as perfectly and fpeedily as
other embryos which were immerfed in fe-
men. Your refledlion on this oCcaiion is ver/
juft; fince fo fmall a drop of femen, mixed
with fo large a quantity of water, is fufficient
to animate the embryo, it is very natural to
infer, that the furplus furniflied by the male
does not concur in the operation. But Na-
ture is never fparing in what concerns the
propagation of the fpecies: fheis determined
not to mifs her aim, and fhe would run the
rifk of miffing it by too great ceconomy^
She, perhaps, alfo has an eye to the pleafure
the male receives from fruition -, for emiffion
is without a doubt a pleafmg fenfation to him,
and this kind mother is defirous that all hef
children iliouldfind enjoym.ent; otherwife too
the male would want an incentive.

CLii. You eafily conceive, my dear phi-
lofpher, all the attention I have paid to this
interefting palfage of your letter. I ima-
gined, that 1 beheld with you the fmall pores
in the cover of the embryo, contrived for the
introdudtion of the femen. Your details on
this point fully prove, that you have not fuf-
fered yourfelf to be impofed upon ; and that

thefc

LETTER Ii: 30 J

thefe little mouths, of which I had fufrcvft-*-
ed the exillcnce, are certainly to be luund :
and fince they are difperfed over the whole
cover, and this cover is perforated like a fieve,
it can no longer be matter of furprife, that
fecundation fucceeds equally well, -wherever
the embryo is touched with the needle, after
it has been dipped in the femen. The quef-
tion now is, whether fuch apertures exift in
the covers of the embryos of every fpccies ;
and how probable is this, after all that has
been difcovered concerning the myftery of
fecundation: I do not then doubt, and I
have indeed never doubted, that if the germ
of the pullet, of the lamb, of the calf, were
as perceptible as the tadpole, you would de-
ted: abforbent pores, iimilar or analogous to
thofe in the tmhr/o of your amphibia. I
would afic, if we have not the ftrongeft
proofs that fecundation is cftt8:QdJrom "with-
out, and if it be thus effeded, is it not ne-
celfary, that there iliould be little pores pre-
pared for the reception of the fecundating li-
quor ? Thefe abforbent pores and their de-
pendencies contain, without doubt, anato- .,
mical peculiarities^ which we ihould admire^
if we were permitted to defcend to the bottom
of the abyfs. Each pore is probably the

orifice^

304 LETTER ir.

orifice of a veffel communicating with the
heart, &c.

^Lviii. I now come to the moft curious
and important article of your excellent letter.
I fufpe<fted not, I own, that you had already
fuGceeded in the artificial impregnation of
the female of a large animal, by means of a
fmall fyringe, a projedt I mentioned in my laft
letter. This is one of the moft important
and interefting difcoveries, that have prefent-
ed themfelves to the notice of naturalifts and
philofophers fince the creation of the world.
Your mode of proceeding, and your fcrupu-
lous attention to eftablifh, in the moft rigor-
ous manner, the truth of this artificial im-
pregnation, put it beyond all con troverfy. I
bad nooccafion for your fecond letter of Dec.
15, to be afiiired, that you had negledled
nothing to obviate tlie moft fub tie objed:ion.
Your bitch was then clofely penned up for
twenty-three days before the operation : on
the 1 3th file began to be in heat; on the 23d
youinjedled' thefemen, and you kept her in
clofe confinement twenty-five days longer;
on the fixty-fecond after the injection, jfhe
brought forth three whelps well conditioned,
very lively, and refembling both the dam and
the dog which had fupplied the fecundating
liquor. XNlothing can be more exad: or better

afcertained ;

LETTER Ii; ^05

afcertained; nothing can be finer or more
original than this experiment. I congratu-
late you fincerely on your fuccefs, and what
adds greatly to it is, that it was obtained with
lefs than thirteen grains of femen. This ex-
periment agrees perfedly well with thofe
which you have executed on amphibious ani-
mals, and we have good realbn for inferring,
that the dofe of femen w^hich produces fe-
cundation in large animals, is very inconfi-
derable. I even prefume, if you could ef-
fect the fecundation of the embryos of a
large animal in the ovarium, by the procefs
I pointed out to you, you would obtain the
fame refults as the amphibia afforded ; and
that a drop of femen i-5oth of a line in
diameter, would be fufficient to animate the
embryo.

You are now in poffeffion of a fure and
eafy way of afcertaining what fpecies can
procreate together ; and the experiments you
propofe attempting next fpring, by putting
your voluptuous fpaniel in the company of
cats and rabbits, promife not fo fair as thofe
which you wdll make, by introducing the fe-
men of this fpaniel into the uterus of a doe-
rabbit and a Ihe-cat, and on the other hand,
by introducing the femen of the male rabbit
^nd cat into the uterus of a bitch. You hold

Vol. ii. X in

306 L E t T E R II.

ill your hand a precious clue, which will
guide you to the moft important and unex-
pedred dilcoveries. I know not, whether
what you have now difcovered, may not one
day be applied in the human fpecies to pur-
pofe we little think of, and of which the
confequences will not be trivial. You con-
ceive my meaning : however that may be, I
confider the myftery of fecundation as nearly
cleared up. What remains principally to
be difcovered, is the formation of the mule,
and what occafions the different marks of
refemblance between children and their pa-
rents ; and this brings me to your CLixth
article.

CLix. You do me great honour, my dear
affociate, by fufpending your judgment be-r
tween Haller and me, with refpedl to the
manner in which the mule is formed. What I
did not the authority of the great Haller, in
your eftimation, overbalance mine, which is
fo much lefs weighty ? I would not have heft-
tated a fingle moment to admit with hira,
that the femen adts merely as a limple ftimu-
lant, could I have accounted for the conver-
fion as it were of the horfe into the mule.
His hypothefis, from its greater fimplicity,
is more acceptable to the mind. But is it
fufficieat irrall cafes ? Ja ordei: to account for

th(i-

LETTER 11. ^oy

the formation of the great mule, is it enough
to fay, that the femen of the afs is a more
powerful ftimulant than that of the horfe ;
and that hence it fo much elongates the ears
of the embryo contained in the ovarium of
the mare ; for how then comes a part of the
embryo's tail to be obliterated ? Why is its
crupper fo flender ? and above all, how
comes the larynx to be fo different from that
of the horfe, and fo nearly to refemble that
of the afs ? I cannot, I own, conceive that
the inftailtaneous ad:ion of a drop of femen
on the heart of the embryo can produce ef-
fe(fl:s fo great and fo permanent^ on the other
hand, I have againil me the complication of
my own hypothefis, of which the expaiition
required a long feries of propofitions, which
make it appear ftill more complex, and not
to be comprehended, but by readers of great
attention and much accuftomed to analytic
deductions. Hence many have committed
ftrange miftakes, with refpedl to my principles
and their application.

There is alfo another circumftance, which
feems to militate againft my hypothefis; this
is the very trifling portion of femen which is
fufficient for generation 5 it is not eafy to
comprehend how a drop of femen, fo difpro-
portionate to the whole body of the embryo,

X 2 «an

308 LETTER Ii:

can ferve for its firft aliment. But this diffi-
culty preiTes on Haller as much as upon me ;
for it evidently implies, that one kind of fe-
men adls with more force than another on
certain parts, and occaiions a more ample
evolution; that the femen of the afs, for in-
ftance, impels the blood with greater violence
into the arteries of the ear ; thefe are his own
terms : he admitted, therefore, that the fe-
men of the afs arrives at the arteries of the
ears of the embryo of the horfe, how, other-
wife, could the fimple adion of this femen^
on the heart of the embryo, propagate its
impreffion to the ears, and caufe fo exceffive
an evolution of them ? Befides, how come
the ears to be the only part of the head
which grow to fuch a prodigious length, fmce
all partake alike in the impulfe of the heart.
Further, Haller fpeaks of the power poffef-
fed by the femen, of occalioning the growth
of the beard, and of lengthening the tufks
of the elephant and the wild-boar : he adds,
if it has this power of promoting a greater
growth in certain parts of the body which
prepares it, than in others, it may have the
fame effedt on the body of the fetus which it
animates. Would not this ferve to fhew,
that our author tacitly fuppofes a difperfion
of the femen through the whole body of the

embryo?

LETTER II.' 309

embryo ? I fuppofe the fame thing ; and you
have no greater difficulty than myfelf, in con-
ceiving the prodigious divifion of which a
drop of femen is fufceptible. What we
know of the divifibiUty of matter fmooths
this difficulty. It is much to be regretted,
that our great phyfiologift confined himfelf to
mere generalities on this fubjedl, and that he
did not apply his hypothefis to the explana-
tion of the principal peculiarities offered by
the mule. *' It is true, fays he, my anfwer
does not explain the mode or the mecha-
nifm by which the femen of the male excites
the germ of the ear, and caufes fo large an
evolution of it. But I am not obliged to
explain this mechanifm, provided my fad:s
are well eftablifhed. The influence of the
femen on the growth of the beard and horns
is demonftrated, though the manner in which
it afts may be perhaps for ever unknown. It
is fufficient to fhew, that there is a certain
power in the femen of the male, which de-
termines the growth of the fetus, fo that
certain parts come to be more developed : It
would not be more juft to demand an expli-
cation of the mechanifm by which this is
brought about, than the reafon, v/hy the ab-
forption of the femen of the male produces
the growth of the beard.'*

X 3 I Aould

310 LETTER II.

I ihould have efcaped much labour, if m
imitation of my illuftrious friend, I had con-
tented myfelf with repeating, that the femen
of the male has a certain power to caufe a
greater developement of certain parts. But
fo vague an explanation not fatisfying me, I
have endeavoured to analyfe fads, and from
this analyiis I have fought a folution, which
might be applicable to the moft effential pe-
culiarities of thefe fadls. In a word, I have
fuppofed that the ftrong traces of refemblance
between the mule and afs, implied in the fe-
men of the latter, fomething more than a
fimple ftimulating power: am I deceived,
think you, in this conclufion, and are you
inclined to believe, that a fimple ftimulating
power is fufficient for the whole ? I cannot
yet prefume fo much, but it is very poffible,
that a more fatisfadory hypothefis than mine
imy be imagined, and I will be the firft to
adopt it.

CLXvii, You have done every thing you
poffibly could, in order to deted the real na-
ture of the femen of your amphibious ani-
mals. It is not then either vifcous or inflam-
mable, acid or alkaline; and yet hov/ won-
derful is its energy i It evaporates like water,
and it is very well worth remarking, that its
moft volatile part is precifejy that which is

unfit

LETTER Ii: 311

unfit for fecundation. This part, in all ap-
pearance, is only lymph, or rather fimplc
ferum, deftined to prevent the too great vif-
cidity of the fecundating part. It would be
an interefling employment to carry on thefe
refearches to the femen of large animals:
they have not been pufhed fo far as they
ought. Nor would it be lefs interefting to
know, whether the femen of large animals
incorporated like that of your amphibia, with
a great quantity of water or other liquors,
would in like manner preferve its energy.
The happy experiment made on your bitch,
points out the path that fhould be followed
in order to afcertain this point. The feed
has been conftitut^d in a fecret relation to the
nature of the power which caufes irritability,
iince it is deftined to increafe the operation of
this power; but we have not yet fufficient
knowledge of the nature of irritability. 1
would not, however, venture to affirm, that
there does not exift in nature fome other' li-
quor befides femen, capable of caufing the
evolution of the germ. Who knov/s, if the
powder of the ftamina of certain plants, may
not make fome impreffion on certain germs
belonging to the animal kingdom ? This is, if
you pleafe, a filly idea, but I lay before you
every thing v/hich palTes through my brain.

X 4 > I could

312 LETTER 11^

I could wiili, that the powder of the ftamina
of the barberry might be tried, of which the
fetid and penetrating fmell feems to announce
great energy. Animals and vegetables com-
pofe but one family, and their analogies are
very numerous. Inverted experiments of
this nature ought to be attempted, for it is
only by infinitely multiplying the combina-
tions of beings that our knowledge increafes,
I am always a little miftruftful of our general
Conclufions, however apparently well founded,
becaufe our premifes are always more or lefs
particular.

Thus, my dear friend, I have gone over
all the paragraphs of your excellent letter ;
and I wifh my refledlions may afford you fatis-
faction,

I began this long letter the 9th of Decem-
ber, and it has employed me till this day, the
loth of January. If you fend me any account
of your new experiments on the generation
of plants, I ihall be able to make ufe of it at
the end of Part the xth, provided it does not
come too late.

My wife was very fenfible to the politenefs
of your obliging recoUedlion of her. She
defires me to prefent her compliments and
congratulation on the fuccefs of your in-
quiries. Her health is rather better this

winter

LETTER II. 313

winter than it was the laft ; but returns of the
chohc, from time to time, make her fuffer
feverely.

You and the univerfity have loft a great
protedlor : but I am certain, that her fuccefTor
will patronize the arts and faiences. The
Guardian Angel of Auftrian Lombardy,
Count Firmian, has fuftained a great lofs, and
his feeling heart will be deeply fenfible of it.
Prefent to that Sage frefh aflurances of my
refped: and unfeigned wifhes for his welfare.
Accept yourfelf the vows which I am incef-
fantly offering for you, my dear and celebrated
friend, and entertain as much efteem for me
as I feel for you,

/ ^he Contemplator of Nature^

END OF THE LETTERS.

A DIS<

C 314 ]

A

DISSERTATION

CONCERNING THE

GENERATION

OF

CERTAIN PLANTS.
CHAP. 1.

6ENERATION OF THE PLANTS, DENOMI*
NATED BY LINM^US SPARTIUM JUN-
CEUM, VICIA FABA, PISUM SATIVUM,
DOLICHOS UNGUICULATUS.

i. TT WHOEVER is acquainted with Na-
? ▼ turai Hiflory cannot be ignorant,,
that the three principal fyftems refped:ing the
generation of animals, the fyftem of the
cvarijis'^ that of the vermiculijli^ and that
founded upon the two liquors, have been trans-
ferred, with the neceifary modifications, to
" plants. Some think, that the embryos pre-

exift

DISSERTATION 111. 313

cxift in the ovarium, others that they are
tranfportcd thither in the impregnating pow-
der, and others beUeve, that they are ge-
nerated in the ovarium, by the combina-
tion of two fecundating prmciples, the one
furniflied by the piftil, the other by the fta-
mina.

My chief purpofe being to invelligate the
generation of certain plants, I conceive there
can be no better way to arrive at truth, than
to fix my attention chiefly upon the ovarium.
That I might have the greater chance of far-
prifmg Nature in her operations, I deter-
mined to examine this organ at three diffe-
rent periods ; before fecundation, at the time
it takes place, and after it has been eftedled j
or, what amounts to the fame thing, after
the afperfion of the pollen. I was there-
fore obliged to examine the flowers w^hile
they were yet clofed, when they were in full
bloffom, for that is the feafon of impregna-
tion, and after the petals had dropped. I begin
with the fpecies denominated by Linn^us and
others, Spartium Jimceum^ Ruihy-twigged
broom.

II. From the nature of this plant, as well
as of others without number, the flowers of
the fame branch are not all equally forw^ard,
fome being in the flate of a fmall bud, —

thefe

3l6 DISSERTATION III,

thefe are fituated highefl; on the branch;
others already blown, or about to blow, —
thefe occupy an intermediate fituation ; and
others again fallen or falling, — thefe grow on
the loweft part. The fame branch therefore
furniflied matter for various obfervations.
The fmalleft buds were firft to be examined.
They are perfectly compadl, and form a folid
body, fcarce a line in length. If they be
dexteroully opened with fine inftruments, the
petals may be difentangled and brought into
view. They are of a light green, without
any tinge of yellow, which is the colour of
the ripe flowers. When the petals are re-
moved, the ftamina and piftil, the organs of
generation, come into view. The powder
of the antherae may be perceived ; it is far
from being ripe, as is evident, not only from
the extreme minutenefs of the granules of
which it is compofed, but from its want of
volatility, a property it eminently poiTefTes
when mature. It is now fixed to the antheras
by means of a vifcid matter. The piftil, ex-
tremely tender, arifes from the middle of the
flowers. If its bafe be freed from the fur-
rounding teguments, and attentively examin-
ed with a glafs, the pod may be feen formed
about i-ioth of aline in length. If the pod
be examined externally, feveral tumours may

' be

DISSERTATION III. 317

be feen along the fides, which, when ob-
ferved againft the Ught, are found to be pro-
duced by granules lodged within the pod, or,
as I fliall call it, the ovarium. Upon open-
ing the ovarium longitudinally, thefe granules
are found to be feeds, of very fmall fize and
round iliape; they are diftributed in their na-
tural order, in fo many depreffions or fockets,
and attached by filaments {appiccature) to the
infide of the ovarium, juft as the ripe feeds
are in the ripe and dry pods of the plant.
Thefe feeds are not found, upon diffeclion, to
confift of an external cover, and a nucleus
compofed of two lobes, wath a germ or plan-
tule, as in their mature ftate ^ but they exhi-
bit an apparently homogeneous fubftance,
fpongy, and like a tender jelly. From the
reafonable fuppofition which I formed, that
thefe are the feeds, it follows, that they exifl;
in the ovaria at leaft twenty days before the
flow^er is in full blooai, or in other words, be-
fore fecundation, Flowxrs at lead of equal
fize of another branch, growling from the
green ftem of the fame plant, were not full-
blown before the twenty-fifth day.

III. The dilfection of feveral buds, larger
by about one-half than the preceding, pre-
fented the following phsenomena. The pe-
tals, which were beginning to alfume a yel-

lowifli

3l8 DISSERTATION III.

lowifh hue, were not now fo clofe and corn-
pad:; and the fecundating powder ftill ad-
hered to the fummits. The ftamina were
become longer and thicker, as alfo was the
piftil. The ovarium was not fo fmall, and
the feeds had grown in proportion; their
fubftance was not fo gelatinous, though it
continued ftill homogeneous and fpungy.

In flowers a little further advanced, the
only difference confifted in an increafed iize
of the petals, ftamina, piftil, and feeds. Nor
was there any eflential change when the petals
were expanded, and the powder of the fta-
mina, being now mature, might be ihaken
from the antherae by the flighteft agitation,
and diftufed itfelf in a cloud through the air.
In the feeds I could not at this period difcover
either lobes or plantule, but they were of a
o;reeni(h colour and uniform fubftance, which
was fpungy and full of moifture. Yet I
could diftinguiib the lobes and plantule in the
ripe feeds contained in tbofe pods, which
had acquired a black colour, and were grown
dry. It was therefore neceflary to infer, that
the two lobes and the plantule are either ge-
nerated, or rendered vifible during the ripen-
ing of the feeds. Hence, in order to dif-
cover the generation or the appearance of
thefe parts, I was obliged to continue my
y obfervatiops

DISSERTATION III, 319

obfervations till I had gained fome latisfac-
tion upon this curious and interefting point.

I began with the ovaria or pods, from
which the riowers had fallen Ibme time. In
ten days afterwards there was no difference.
On the eleventh fome new appearances began
to take place in the feeds. They were no
longer round, but refembled an heart, of
which the bafis was attached to the pod by
an appendix, and towards the apex, when
gently compreffed, there appeared a whitiili
point in motion. When the heart was cut
open longitudinally and the iniide infpecfted,
this white point proved to be a fmall cavi-
ty, inclofmg a drop of liquor, which had
been made to move by the preffure of the
fingers.

Twenty-one days after the pods were
ftripped of their flowers, the cavity, which
at firft appeared at the apex, was enlarged,
and extended much farther towards the bafc ;
it was full of a tranfparent liquor, with
which the fpungy fubftance of the feeds wag
alfo moift. On the tw^enty-fifth day the ca-
vity v/as more enlarged, and ftill full of li-
quor; it moreover contained a very fmall femi-
tranfparent body, of a yellowifh colour, ge-
latinous, and fixed by its two oppofite ends td
the fides of the cayitv.

jji

^lO DISSERTATION III.

In a month the feed was much enlarged,
and its ihape is changed from a heart to a
kidney ; the Httle body contained in the cavity
is increafed in bulk, is become lefs tranfparent
and gelatinous, but there appears no fign of
or2:anization.

On the fortieth day the cavity, now. grown
larger, is quite filled with the body, which
deferves to be more particularly examined.
It is furrounded by a thin membrane, fome-
what vifcid and tender^ after this micmbrane
is removed, the body appears bare, and with-
out any other teguments; it is of a bright
green colour, and may eafily be divided by
the point of a needle into two portions, in
which are manifeftly recognized the two
lobes ; within thefe we may eafily perceive
the plantule exceedingly fmail, and attached
to the lower part. - The lobes, together
with the membrane, are afterwards defended
by a hufk or Ikin, which forms the outfide of
the feed.

The reader will eafily guefs what after-
wards happened to the pods as they grew
riper. The lobes and the plantule were only
more and more developed, and by degrees
acquired greater firmnefs. And in this man-
ner did the feeds pf the broom arrive at ma-
turity*

V. The

DISSERTATION III. 32!

V. The foregoing obfervations fhew, i.
That the feeds of this fpecies exifl in the
ovarium many days before fecundation. 2i
That they remain for fome time folid, and
then a cavity, containing a Uquid, is formed
in them. '^. That after fecundation a body
begins to appear v^ithin the cavity, fixed by
two points to the fides ; and when in procefs
of time it has attained a larger fize, it proves
to be the two lobes inclofmg the plantule.
4. That the ripe feed confifts of two lobes
adhering to the plantule, and furrounded by
a thin membrane, v^diich is itfelf covered
with a huik or cuticle*

Thefe deductions illuftrate the generation
of the plant in queftion. We learn, that the
embryos do not appear till after the falling
of the flowers, and confequently not till after
fecundation, though the feeds, or, to fpeak
more properly, the integuments of the feeds
may be feen long before.

VI. Having analyfed the frucflification of
this fpecies of broom, I proceeded to that of
the common bean, Vicia Faba, I began
with thofe which had the fmalleft bloflbms*
They appear externally of a green colour, and
likewife internally, if the tender petals be un-
ravelled ; here and there, indeed, the green
approaches to a white. IThe ftamina are vi-^

Vol, 11. Y fible^

322 DISSERTATION III.

fible; the antheras, inftead of pollen^ ^xhU
bit a vifcid gelatinous fubftancci The piflil
is of a white and green colour ^ towards the
apex it is villous^ and within the bafe or ova-
rium, it it be infpeded againft the light,
may be perceived the feeds. It may be re-
marked, that the ovarium of the bean more
eafily fplits into two than that of the broom,
and that the feeds of the former plant are ill
like Gireumftances larger than thofe of the
latter. The feeds of the bean are roundifb^
but on one fide there is an hooked and fharp
beak.' They are femi-tranfparent, gelatinous,
and when opened, are found to be folid and
without a cavity.

If bloffoms not quite fo fmall be examined,
the powder of the ftamina is perceptible ; it
is found to be imbedded in a glutinous fub-
ftance. The ovarium having now attained a
larger iize,- contains feeds proportionally in-
creafed in fize ; they are neither fo gelatinous
nor fo tranfparent,. but they contain no cavity.
Other feeds further advanced, and belonging
to bloffoms about to open^ or already expand-*
ed, are in the fame ftate.

The cavity is not vifible till the 3d of 4th
day after the falling of the flowers ; it is then
found to be full of a tranfparent liquor. The

feed^

\ ,

DiSSEJtTATION III. ^Z^

feeds and the cavity increafe together, and
fifteen or twenty days after the fall of the
petals, the cavity contains a body, which,
when magnified, fee'ms to be fplit into two,
though the obferver cannot be certain of this
till afterwards 3 when if he opens feeds nearer
maturity, he will find them to divide very
eafily into two portions. Thefe portions are
manifeftly the two lobes, within which is
contained the tender nafcent plantule. If the
lobes and the plantule be treated with ex-
tr^enie care, a mucous filament is found at-
tached to the plantule, w^hich, after pafling
between the lobes, is implanted in the fub-
fiance of the little feeds. The lobes and the
plantule are merely developed in procefs of
time. They are covered, as iri the above-^
mentioned brooni, with the integurrients of
the feed.

Vii. I fhall relate at once my dbfervatlons
up6rl peafe and kidfiey-beans^ the appearances
they offered being perfed;ly alike. The feeds
are found in the ovarium full formed, when
the flowers are little advanced^ and when the
buds are yet fcarce vifible. The feeds now
feem to confifl: of an homoo-eneous fub-
fiance, and are without any internal ca-*
vity. The fame may be faid of them when

V z they

3^4 DISSERTATION 111.

they are become many times larger, and when
the powder of the antherae is ripe. The ca-
vity begins to be vifible fome days after the
withering of the flowers, and in ten or twelve
days more it is enlarged, and a white muci-
laginous point connected by a flender filament
with the feeds may be perceived in it. This
point is the rudiment of the lobes, betvyeen
which the plantule may be diftinguiihed by
the aid of the microfcope. What follows
may eafily be imagined : the lobes and plan-
tule increafe in fize, and their increafe implies
the growth of the feeds which contain the
lobes.

If we compare thefe obfervations upon
kidqey-beans and peafe with the foregoing
upon broDm and beans, we lliall find, that
they all contribute to prove that the feeds, or
their integuments, exift before fecundation,
but that the plantule and the lobes cannot be
fccn till afterwards.

It would therefore appear, that thefe re-
fults do not agree with my obfervations on
amphibious animals; for in them I found
the fetufes before impregnation. But are we
immediately to conclude, that in the procefs
of generation Nature follows two different
methods in plants and in animals ? The prin-
ciples

DISSERTATION IIU 325

clples of found reafoning do not permit me to
make fo hafty a declaration ^ they require,
that 1 fhould continue my refearches on plants.
Thefe refearches I undertook, and a relation
of part of them Ihall be the fubjecft of thp
following chapter.

Y 3 CHAP,

326 DISSERTATION III,

CHAP. II.

GENERATION OF THE PtANTS PENOMI-?
NATED BY LINN^US, RAPHANUS SA-
TIVUS, CICER ARIETINUM, IXIA CHI*
NENSIS, DELPHINIUM CONSOLIDA, CU-
CURBITiV PEPO, CUCUMIS SATIVUS,
EXAMINATION OF THE POWDER OF THE
STAMINA.

VIII. 'TTyAphaniLs fativus, commmi RadiJI:*
^L The feeds are viiible in the -ova-
rium long before the powder of
the antheraB is ripe. They are folid, and
continue fo till twelve or fifteen days after the
falling of the flowers : the ufual cavity then
appears, p.f fmall dimenfions at firfl, and
full of liquor, but fucceffiyely enlarging, in-
fomuch that about the aoth day, it, occupies
almoft all the infide of the feeds. In three
or four days more, the lobes are feen fur-
rounded as ufual by a tranfparent liquor 5 an4
we may foon afterwards perceive between
them a mucilaginous filament, attached by
one end to the plantuls, aqd by the other to
the internal cavity of the feeds. When the

feed§

DISSERTATION III. 327

feeds are nearly ripe, the two lobes are con-
iiderably increafed; they refemble a pear with
its ftalk; the ftalk is implanted into the corir^
cave furface of the feeds. If the lobes be
taken out and carefully examined, the ftalk
appears to be part of the plantule; and in-
ftead of two lobes, the nvimber obferved in
the plants before mentioned, there are four ;
the two fmaller are implanted in the two
greater; they are all united, and fo attach-
ed to the plantule, as with it to form one
|:>ody.

IX. Cicer arietlnum^ Chick-pea. The pif-
til in this plant reprefents in miniature a
gourd, of which the belly is the hafe of the
piftil, or, as I call it, the ovarium. If this
be opened longitudinally twelve or fifteen
days before fecundation, two pointed feeds,
folid and of a green colour, come into view.
As the parts of .fructification ripen, the ova-
rium fwells and takes the form of a purfe, to
which the feeds are attached. About four or
five days after fecundation, the cavity begins
to form, and on one fide of it may he perceiv-
ed two very minute lobes ; if they be care-r.
fully opened, the plantule is feen attached to
the feeds by a mucilaginous filam^ent. No-
thing further takes place except a progrefiive
^volution.

Y 4 X. Ixia

21^ DISSERTATION IIJ,

X. Ixia chinenfis. Having opened longitu-.
dinally the ovarium of one of the fmalleft
buds, which is oblong and prominent at the
centre, we find the pyriform feeds difpofed
in their natural order, and perfectly folid
within. The fame thing may be obferved
when the petals are opened, nay, after they
are fallen, and flill nine or ten days more
elapfe before the cavity begins to open, This
plant is diftinguifhed by a peculiarity which
muft not be omitted. At firfl: the cavity is
full of a tranfparent liquor, which in time
thickens, and at length is converted into a
white gelatinous matter, not unlike coagu-?
lated milk. The coniiftence becomes gradu-
ally firmer, and before the feeds are ripe, re-
finance is felt on attempting to cut it with a
knife. This fubilance, thus hardened, oc-
cupies the whole cavity of the feeds, nor can
there be perceived the fmalleft vefl:ige of the
lobes. My obfervations were made upon
feeds not yet arrived at perfedl maturity, but
I could not continue them for want of riper
feeds. Are we to fuppofe that the fubilance,
which is at firft liquid, then gains fome con-
fiftence, and at laft becomes hard, performs
the office of lobes, fo that they are produced
in this inftance in an unufual manner ; or is

it

DISSERTATION Ilf. 329

It more probable, that the lobes appear later
than in other feeds ? The phaenomena of ano-
ther plant, of which I am now to fpeak, in-
cline me rather to the latter opinion.

XI. Delphinium confolida, Larkfpur, fub-
divided larkfpur. The appearances noticed
during the growth of the feeds of the Ixia,
recurred on the prefent occafion. The ca-
vity, which is ufually formed after the falling
of the petals, is foon filled with liquor, at
firft tranfparent, then whitifh, and afterwards
of the colour and confiftence of milk. If
the feeds be now boiled for a fliort time, the
milky liquor is changed into a matter like
pomatum. There appears, upon examina-
tion, no fign of organization. When the
feeds are nearly ripe, the confiftence of the
white liquor is increafed, and when they are
arrived at maturity, its hardnefs is confider-
able. The plantule and the lobes may now
be diftinguiihed, but they are fo buried in the
midft of this indurated matter, that it is dif-
ficult at firft to diftinguifh them certainly, as
well on account of their minutenefs as their
white colour. This obfervation, which
agrees fo nearly with the preceding, leads me
to fufpedl, that the milky liquor of the Jxia,
which is firft coagulated and then harden-
ed, does not conftitute the lobes, but only

enclofcs

3^0 DISSERTATION III.

enclofes and conceals them. They are invl^
fible> either on account of their minutenefs,
or becaufe the feeds are not yet ripe. In the
prefent fpecies, the late appearance of the
lobes, which does not takes place in much
lefs than a month after fecundation, is very
remarkable (a),

XII. Ciwiirbita PepOy Common Pumpion
or Pumpkin. Difregarding for the prefent
the male flowers, a^ having no relation witl^
the prefent inquiry, on account of their fte^
rility, I direcfled my attention to the female
Eowers, beginning with the bloifoms that
were leaft advanced; fmall,. however, as they
are, the little pumpion is already formed un^
der the bud, and the feeds within it are very
Yifible. In this plant there is a peculiarity m
their ftruc^ure. They are not compofed of an
homogeneous fubftance, as the unripe feeds
of other plants, but confift of two matters.

{a) I found, by obfervations made a year afterwards, or^
more advanced feeds of the Ixia, that my fufpicion was juft,
"When a longitudinal fedlion is made along fuch feeds, the plan-
tule is very vifible ; it has the ftiape of a cone ; the bafe lies at
the bottom of the feed, and the apex reaches about as high as
the middle. The whole plantule is imbedded, and hid in the
milky matter, which at this period is very hard. I muft
moreover obferve, that notwithftanding all my pains, 1 could
not difcover the lobes ; perhaps the part I call plantule might
ferve in their Head. The appearance of the plantule is as lattj
1^ the feeds of the Ixia, as in thofe of the larkfpur.

afhell

DISSERTATION III.' g^f

^ fliell and a nucleus. When the feed is cut
tranlVerlely, thefe two fubflances appear in
the plane of feftion; if a portion oi the di-
vided feed be held by the flat fides between
the finger and thumb, ana prcilure be made
towards the cut, the nucleus quits the hufk,
and flies into the air, as the ftqne of a cherry-
does when prefled in like manner. If the
nucleus be taken whole out of its coyer, it
appears in the fhape of a pear with its fi:alk,
and bears, moreover, a perfed: refemblance
to the lobes with the plantule. But are we
to conclude, that the plantule is really vi-
fible here before fecundation ? I confefs, this
iirfl obfervation on the frudification ■ of the
pumpkin, was very near leading me to adopt
this opinion. But one circumllance fug-
geflied a doubt. In other plants the lobes
are eafily feparable into two, and fome-
times into four (yiii) j in the prefent
cafe, the nucleus would not admit of
fuch a feparation, but formed a perfed:
whole. The beil way of removing my per-
plexity, evidently was to profecute my obfer-
vations. From the examination of three
larger buds I learned, that the nucleus yet
confifted of one body, and that it adhered fo
iirmly to the cover, that it could not at al],
pr at leail not without great difficulty, be

parted

g^Z DISSERTATION HI.'

parted from it. But the cover or rind ap-
peared much more complex than I had at
firft conceived. It confifts of three diftind:
membranes. The firft or outermoft is the
moft thin and deHcate of all ; it may be de-
nominated the cuticle or epidermis. The
fecond, which lies immediately under the
firft, is thicker, and of a whitifli colour, and
has a degree of hardnefs approaching to that
of wood ^ there is fome difficulty in fepa-
rating it from the third, which inverts the
nucleus ^ this innermoft fkin or membrane is
greenifh and firm, but not fo firm as the
fecond.

The infpedtion of the feeds, twenty-five
, days after the falling of the flower, gave me
an opportunity of obferving other new cir-
cumftances. The nucleus, which fo much
refembled the lobes, had difappeared, and in
its ftead, there was a membranous fac, ter-
minated by a beak, that was attached to the
infide of the feeds. The fac was fome what
tumid, with a liquid ftagnating within it, as
became evident whenever it >vas perforated.
By gently laying hold of the beak with a pair
of forceps, the little fac may without diffi-
culty be entirely removed. It is compofed
of two membranes, which, when opened,,
are found to contain a very tender rnucilagi-

nous'

DISSERTATION iK 33^

nous body full of moifture. This body
arifes from the infide of the apex of the
feed, and extends about half its length ; it
is attached to the place at which it termi-
nates. The flighteft touch breaks and de-

- ftroys it. When examined by the micro-
fcope, it appears reticulated, whence I con-
clude that it is organized.

In feeds further advanced, when the flowers
have been withered above a month, the mu-
cilaginous body enclofed in the membranous
fac is much enlarged, and at the infide of
the apex of the feed appears a white, folid,
and conical particle, which, when attentively
examined, appears to be the germ or the
plantule in miniature. To the plantule are
attached the two lobes like it, of a white
colour, and exceeding it in fize^ the mucila-
ginous fiUment above-mentioned palTes in the
middle between them, and is inferted into
the plantule. It is eafy, from what has been
faid above, to guefs how the feeds gradually
advance towards maturity.' The mucilagi-
nous filament enlarges in its dimenfions, the

> plantule increafes, and the two lobes ad-
vancing in bulk and mafs, come at laft to oc-
cupy almoft all the infide of the feed. It ap-
pears, therefore, that I fhould have been
greatly deceived if I had taken the nucleus,

which

J34 ^ ISSERTATIG!^ lit,'

which is found within the feeds before tticf
opening of the flowers, for the lobes and the
plantule, fmce thefe parts do not make their
appearance till a month after the withering of
the petals.

±111. Cucumis fativiis^ Cucumber. My
obfervations on rhe feeds of this plant, fo
exactly refemble thofe on the feeds of the
pumpion, both with refpecl to the appearance
of the nucleus iDcfore fecundation, the mem-*
branous fac, and the gelatinous fubftance,
which are obferved afterwards, and laft of
all the lobes and plantule, that I think it un-
neceffary to enter into a particular account of
them. I fhall only fay, that in the cucum-
ber the plantule and the lobes feem to me to
become vifible ftill later : they at leaft were
very fmall in olie inftance, when the fruit was
nearly ripe, and beginning of courfe to turn
yellow*

I afterwards proceeded to examine other
plants, Hihifcus Syriacus^ the Syrian flirubby
Mallow, Alcea rofea^ rofe-flowered, or com-^
men Hollyhock, Acanthia riiGilis^ fcft or
fmooth-leaved Acanthus, Convohiilus purpu^
reus^ purple Bindweed, to which may b^
added Ocymum Bafiliciim^ fweet Balil, Cucur'-
hit a citridlus^ Caimabis Jativa, Hemp, Mer^
curiaiis anniia^ annual Mercury. All thefe

ctssEkTATidisr ni.' 33^

J^lants perfedlly agree in the appearance of
the feeds long before fecundation, and of the
plantule and lobes, fome time after the ripen-
ing and diffufion of the pollen. This general
obfervation perfedlly coincides with the ac-
count of the great naturalift Duhafnel, giveri
long iince in his Phyjiqiie dei Arbres. Speak-
ing of the formation of the feeds of trees
bearing fruit with ftbnes, fuch as the almond,
the peach, plum, cherry, &c. he adduces
many facts to prove, that when a ftone,
which has attained its full fi^e, is opened be-
fore the fruit is ripened, (and we may make
the experiment a long time after fecundation),
it will be found full of a vifcid liquor ; a
white body, he fays, begins to appear within
the point of the kernel, enclofed in a fmall
tranfparent bladder : this body is the rudi-
ment of the lobes With the plantule; they
grow till they fill the whole capacity of the
ftone. From the coincidence of fo many facts,
1 think myfelf authorifed to infer, that thi§
law is obferved by Nature, if not in all plants,
yet in a great number.

XIV. But with which of the three theories
refpedting the generation of plants (I), do
my numerous obfervation befts agree ? My
principal aim was, as I have already remark-
ed, to find, if poflible, data fufficiqnt for tiie

folution

^^6 UISSERTATIOIJ lit;

fokition of this difficult problem. Should
we be content with lirft appearances, we
might perhaps think that fyftem preferable,
according to which, the embryos of plants
are conveyed, at the time of fecundation, by
the powder of the antheras into the ovarium.
The embryos have never been found in this
organ before the afperfion of the powder*
They always make their appearance after the
pollen has been obferved upon the antherae.
It fhould therefore feem, that the exiftence
of the embryos dire(ftly depends upon this
powder; and it may be inferred, with fome
degree of probability, that the embryos pre-
cxift in the pollen; and that when it falls
upon the lligmata, they are conveyed through
particular dudts into the ovarium. A learned
naturalift (^), has accordingly been led to
adopt this opinion, by the obfervations of
fome perfon, who pretended to have feen the
embryos in the ovarium, immediately after
the fummits had difcharged their fecundating
duft. But whoever confiders, with a little
attention, the force of the argument, will
find, that it is not very convincing. It is in
the firft place not true, that the embryos may
be perceived as foon as the powder has fallen
from the ftamina. They do not come into

{a) Nesdham : Nouv. decouvertes faites avec le Microfcope.

view

DISSERTATION III. 237

view for more than a week, and fometimes
not till a month after the difperfion of the
powder, as is evident from all the obferva-
tions I have hitherto related, and from others
which I fliall hereafter relate. In the fecond
place, this mode of reafoning is, as Mr.
Bonnet has very well remarked, illogical ;
when we infer, that the embryo does not ex-
ift in the ovarium before fecundation, becaufe
it is not vilible before that time, we ar-
gue from invifibility to non-exiftence, a fal-
lacious way of reafoning, as many inftances
may be brought to fhew : in the impregnated
egg, for example, the beft microfcopes wuU
not bring the chicken into view, though we
are fure that it is prefent. Notwithftanding
the inconclufivenefs of the argument, there
feems no abfurdity in fuppofmg the embryo of
the plant to pre-exift in the powder, and
thence to pafs Into the ovarium. To remove
thefe uncertainties, I refolved to give my in-
quiries a different direction. ,

XV. If the embryos of plants be really
lodged in the pollen, why cannot we difcern
them by microfcopes of highly magnifying
powers ? The thing did not feem improbable,
and "I thought it would be proper to turn my
refearches to this objed. I accordingly ex-
amined the ripe pollen of feveral plants, and
efpecially of thofe upon \vhich the foregoing
^ Vol. IL Z obfervations

^38 DISSERTATION III.'

obfervations were made. In the flowers of
thefe vegetables, I found the powder to re-
femble very nearly that of others examined
by botanifts, and in particular by Duhamel ;
it formed an aggregate of particles, differing
in figure in different plants; in fome the par-
ticles are round, in others elliptical^ in others
pyramidal or conical, in others of an irre-
gular form. Sometimes they are fmooth,
fometimes prickly, and at others covered
w4th knobs. They are in different plants
tranfparent, opake, yellow, white, blue, or
carnation. The fize varies according to
the difference of the flowers. But thefe
corpufcles are not, according to the com.-
mon confent of Naturalifhs, immediately con-
cerned in the generation of plants. They
areveflcles, fheaths, cafes, — , or by what-
ever name v/e may chufe to diflinguifh them,
for the moft part full of a thin liquor, which,
when they are moiftened, they emit with
force. In this liquor floats a multitude of
very fmall globules, which, at the time of
explofion, are thrown in different directions .
Thole who adopt the theory we are confider-
ing, fuppofe the rudiments or embryos of the
plants to be lodged in this liquor. It was
therefore proper to fix my attention upon it,
and to try whether I could perceive any
thing refembling an embryo. When the

embryos

DISSERTATION III, 339

embryos are firft Teen in the feeds, they re-
prefent a fmall pointed body, to which two
larger bodies a^^e affixed, Uke the clofed
wings of a butterfly 3 thefe are the lobes. I
examined the liquor with great attention, in
order to fee whether it contained any fuch
bodies, or any thing like them. 1 ufed glafles
of various powers, from the loweft to the
higheftj but I could difcover nothing except
the liquor, which in fome cafes is like oil or
melted fat, and the- globules that ufually float
in it. As the liquor, a fubftance without
organization, cannot be what we term em-
bryos, I had only to examine the globules;
but I could perceive nothing in them, which
bore any refemblance to lobes or embryos*
Thefe, as the word globule imports, are
round bodies, or fuch as have nearly that
figure ; they conftantly retain it wdth what-
ever microfcopes they are examined. Nor
did their form change, when I ufed the folar
microfcope, which fo prodigioufly enlarges
objeds. Of thefe fad:s, it is the dired: con-
fequence, that we cannot aifert, with any
probability, that the embryos of plants are
lodged in the pollen.

It may, I am well aWare, be objeded,
that the globules are the real embryos, and
retain their round fhape as long as they cob-

Z z tinue

340 DISSERTATION tita

tinue in the powder; but that as foon as they
pafs into the- ovarium, and find a proper fup-
ply of nouriihment, they unfold the parts
which were before concentrated in a minute
globe, and affume the fhape of the lobes and
plantule ; juft as the tadpoles of the frog and
toad, according to my obfervations, repre-
fent fo many globules as long as they remain
in the body of the female^ but when they
come to be nouriihed with the liquor of the
amnion (^2) put on the real form of the tad-
pole. Such an objedlion-may be flatted, but
it amounts to no more than a bare poffibility,
that the globules floating in the liquor of the
pollen may be the embryos. But I am not
feeking for poffibilities ; I am enquiring
whether the fuppofition is probable; whether
there is any juft motive for fuppofing the
embi'yo to pre-exift in the powder of the
ftamina: and my obfervations fhew not any
fuch probability, or any fuch juft motive.
Not having, by thefe means, obtained the
information 1 fought, there remained one
other chance of folving the problem, by in-
terrogating Nature in a different manner.
This was to try, whether the embryos would
appear and grow to maturity, w^hen the powder
of the antheriB was hindered from ading upon

(^) Diflen. I,

the

DISSERTATION III; 34I

tlie piftils. Should the event be fuch, It would
be evident, that the embryos do not belong to
the pollen, but the ovarium. The experi-
ment might be made in three ways, either by
cutting away the antherae of hermaphrodite
flowers, before they ilied their powder upon
the piftil ; or by removing the male flowers
of thofe plants, in which they grow fepa-
rately on the fame individual before they are
ripe 'y or laftly, by keeping the male plants
at fuch a diftance from the female, that there
can be no fufpiclon of their dull: reaching
them ; this experiment relates to plants pro-
ducing two forts of individuals ; one pro~
vided with ftamina only, the male, and the
other with piftils only, the female. Thefe
experiments, together with fome obfervations,
will furnifli matter for the tv/o follovriny;
^^hapterSo

Z 3 C H A P.

S4^ DISSERTATION IH,

CHAP. III.

GENERATION OF SOME HERMAPHRODITE
AND MONOICOUS PLANTS, UPON WHICH
THE POWDER OF THE STAMINA V/AS
PREVENTED FROM ACTING, CALLED
BY LINNu^US OCYMUM BASILICUM, HI-
BISCUS SYRIACUS, CUCURBITA MELO-
PEPO FRUCTU CLYPEIFORMI, CUCUR-
BITA CITRULLUS.

XVI . T BEGAN with an hermaphrodite
•^ plant, viz. that fpecies of Bafil
which is often raifed in pots, and called by
botanifts Ocyfuum Bafilicumy fweet bafil. I
happened, at the time I conceived the defign
of entering upon this inquiry, to have fome
in blow, and others of which the flowers
were not yet expanded. That I might form
a jufter judgment concerning my experi-
ments, I refolved to compare flowers, in
which the pollen had aded with others, in
which its influence had never been exerted.
My obfervations upon the former were the
following: every bloflbm of bafil had four
flamina, in the midft of which rifes the pif-

. til ;

DISSERTATION III^ 343

til; the flamina, as well as the piftil, are
diftinclly vifible twelve days and more before
the opening of the flower, when the petals
have been cautioufly removed. The feeds
appear at the fame time in the ovarium -, they
are four in number, and have an oval fliape.
They continue folid for feveral days after the
falling of the flowers, but foon afterwards,
while they are increafing in bulk, a cavity,
like that which I have obferved in the feeds
of other plants, begins to form. Within
this cavity, we may in a fhort time difcern a
folid point, at firft fhapelefs, but foon put-
ting on the form of the lobes and plantule.
Meanwhile the cavity becomes more capaci-
ous, as the plantule and lobes grow, and at
length thefe bodies occupy the whole infide
of the feeds. Such is the procefs of Nature
in thofe flowers of bafil, in which the powder
of the ftamina is left to produce its effects :
we have feen that the fame pha^nomena occur
in other plants.

XVII. It is now proper to proceed to the
other more interefting part of our compara-
tive inveftigation, and to obferve what be-:
comes of the embryo, w^hen the influence of
the pollen is withdrawn. At the time when
the flowers were about to open, I cut away
the four anthera?, which now were full of

Z 4 ripe

344 DISSERTATION III.'

ripe pollen. But this operation alone did not
fatisfy me. The exceflive tenuity of that
halitus, which burfts from the pollen (xv),
and which, in the genei*al opinion of bota-
nifts and naturalifts, has an immediate effed:
in generation, (in whatever manner it may
produce this effedt) rendered it neceitary not
only to remove the pollen, by cutting away
the antheraj of thofe flowers upon v/hich the
experunent was made, but alfo to keep at a
diftance the pollen of other flowers growing
on the fame plant. This end was eafily ob-
tained, by plucking off all the flowers as
they were about to expand, except thofe
which were the fubjedl of my experiment.
The pot was placed on a window, and there
grew near it no other plants of the fame
kind, either in pots or in the ground. I can-
not relate what happened without aftonifli-
ment. The feeds, fome time after the fal-
ling of the flowers, ^)ecame hollow within,
and in the cavity appeared the lobes and the
plantule, which grew till they filled the whole
capacity of the feeds, In fhort, the various
phafes aflAimed by feeds that have been fub-
je(5ted to the influence of the pollen, were ob-
ferved without any variation in others, which
may reafonably be fuppofed never to have felt
that influence.

XVIII.

DISSERTATION II f. 34.5

XVIII. I could not however acqulefce iix
this refult: but was rendered uneafy by a fuf-
picion, that fo delicate an experiment had
not been executed with all the neceffary pre-
cautions. According to the common opi-
nion of philofophers, the powder of the fta-
niina exerts its adlion while the flowers are
opening, or foon after they are blown. But
on opening the flowers of bafil two or three
days before their time, I thought that in two
or three inlliances part of the pollen was
ripe, and, that one or two grains had fallen
upon the piftil, v/hich lies very clofe to the
antherce, and indeed almoit touches them.
I therefore fufpedled, that I had cut av/ay
the anthers too late, and after the pollen had
produced its effects. This coniideration led
me to perform the operation upon flowers lefs
forward, and not liable to fuch a fufpicion.
"And now the event was diff^erent. I made
the experiment upon eighty-four blofToms.
The feeds of about one-third of this number
fell before they were ripe. In the ovaria of
the reft appearances w^re exceedingly vari-
ous. Some feeds, notwithftanding it was
the feafon of their maturity, were as fmall as
when the antheras were cut away. In fome
ovaria they were larger, but withered, dry,
or quite fpoiled. lu twenty-five inftances,

they

34^ DISSERTATION III.

they were as well looking and as large as thofc
which had been fubjeded to the influence of
the pollen. I was not however to be fatis-
fied with external appearances. The princi-
pal queftion was, whether they each con-
tained an embryo, or a plantule attached to
lobes ? They ad:ually contained thefe parts,
nor could I, by analyfis or comparifon, per-
ceive any circumftance in which they differ-
ed from the plantule and the lobes of feeds,
upon which the influence of the pollen had
been exerted. Of thefe twenty-five feeds,
certainly never ad:ed upon by the powder of
the antherse, twelve were analyfed in this
manner, and the remaining thirteen were
put into the ground. But they did not ger-
minate, while thirteen feeds of the fame
plant, left to the adion of the pollen, and
fown in the fame place, all came up. The
immediate and moft flriking inference to be
deduced from thefe obfervations is, that the
fecundation, and fometimes the evolution of
the embryos of bafil, depend upon the pollen,
but not their exiftence.

XIX. Whilft I was thus employed upon
bafil, I made obfervations and experiments
of the fame nature upon Syrian ffirubby mal-
low, Hibifcus Syriacus, The anthera^ were
cut away from a great number of bloflx)ms

before

DISSERTATION III. 347

before they expanded. I could not however,
I muft own, be certain, that a grain or two
of powder had not fallen upon the piflil; for
I oftener than once obferved, that it was
quite ripe. Some feeds fell foon after the
operation, but the greater part remained in
their proper fituation, and grew confider-
ably; they would perhaps have arrived at ma-
turity, if the coolnefs of the atmofphere at
the fetting in of autumn, had not prevented
them, as it prevented other feeds of the fams
fpecies, which were left to themfelves, and
muft be fuppofed to have been impregnated
by the pollen. Some of thefe feeds, which
had grown a good deal, but were yet unripe,
were black within and fpoiled, tethers v/ere
white, in all appearance found, and, what is
of chief confequence, they contained a plan-
tule attached to its lobes, which were con-
voluted like cut lettuce. From the plantule
arofe, in fome cafes, an almoft imperceptible
gelatinous filament, of which the other end
was inferted into the feeds.

When I cut off the antheras from the
blown flowers, I performed the fame opera-
tion upon others feveral days before they were
to expand. To effedl my purpofe it was ne-
cefiary to force open the bud, which could
;iot be done without fometlmes injuring a

petal.

2^S DISSERTATION III.

petal. At this time it feemed certain, that
the pollen could not have produced any ef-
fed:, as it was vifcid, and adhered tenaciouily
to the fummits of the ftamina. The refults
exadlly correfponded with the foregoing ob-
fervations. The feeds of feveral flowers
dropped prematurely, while in others they
continued firm, aiad grew confiderably, but
did not ripen : fome were vitiated internally ;
others contained lobes and a plantule com-
pletely developed and found. .

It is obvious, that the confequences of the
experiments on ilirubby mallow and bafil
perfedlly agree; they equally concur to prove,
that although the due evolution of the em-
bryos depends on the action of the pollen,
this powder neither conveys nor produces
them.

XX. Having fufficiently fatisfied my curio-
fity, with refped: to thefe hermaphrodite
plants, I proceeded, according to the plan
laid down in Sed;. xv. to plants bearing male
and female flowers Separately on the fame in-
dividual. My obfervations were made upon
two of this clafs, the pumpion v/ith fhield-
form fruit, Cucurbita Melopepo friiBu Clypei^
formi^ and the citron pumpion, Cucurbita
Citrullus. I bad the feeds of the former
ipecies from the pubhc botanic garden at

Pavia ;

DISSERTATION III. 349

Pavia; they were fownin the fpring at Scan-
dlano, a well-known and very pleafant fort
belonging to the ftate of Modena, and the
place of my nativity : here, during the fum-
mer and autumnal vacations, I employ my-
felf in thofe experimental enquiries, which
are the fubjed: and the foundation of my un-
important literary productions. At my ar-
rival there in the beginning of June 1777,
two individuals, for I had ordered two only
to be raifed, were juft beginning to put forth
a few flower-buds towards the bottom of the
ftalk* At this early period the male flowers
may eafily be difliinguifh^d from the female.
The former, denominated alfo barren by bo-
tanifhs, have a flender ftalk ; while the ftalk
of the latter, where it joins the calyx,
forms a tumour, confifl:ing of the immature
fruit, as is intimated in Sed. xii. I paid
daily vifits to thefe two individuals, and very
carefully watched the progrefs of both forts
of flowers. That there might be no fufpi-
cion of the pollen exerting any influence
upon the females, the males were deflroyed
at their firft appearance. As fruit, when
a fmall quantity only is left upon a plant,
fooner ripens, and grows to a larger fize,
becaufeit receives a greater fhare of nutriti-
ous juice, I left on each of my two indivi-
duals

350 PISSERTATlOU 111.

duals two flowers only ; the buds that made
their appearance afterwards were taken away,
along with the male flowers. Meanwhile
my four goui-ds grew rapidly ^ finding that
towards the middle of September they had
attained the ufual full fize, I gathered one,
in order to infpedt the internal parts. The
fleili was too foft, becaufe the fruit was
not. thoroughly ripe ; but in colour, ftruc-
ture, and tafte, it refembled fruit pro-
duced by plants which had their male flowers,
and which I examined both before and after-
wards at Pavia. The feeds were in great
number, and, as well internally as exter-
nally, were perfedlly formed ; the lobes, in-
deed, to which the plantule v/as attached,
did not occupy the whole capacity of the
feeds, but they had not attained their full
fize. At the end of the month the other
three gourds were quite ripe , I therefore
gathered them, and put the feeds of each
into a feparate box, that I might be able to
examine them at pleafure. The lobes filled
the whole infide of the feeds, and had all
the characters of perfed maturity.

XXI. Thus far there is a perfe(ft agreement
with the obfervations made on the feeds of
bafil, which feemed, notwithftanding they
were deprived of the efficacy of the pollen,

to

DISSERTATION H. 3-1

to have acquired the llime degree of perfec-
tion as thofe impregnated in the ufual man-
ner. But as they did not grow, however
perfedl they might be in appearance, becaufe
they had not been vivified by the pollen
(xviii), I imagined, that for the fame
reafon the feeds of my three gourds would
not grow. It was, however, proper to
make the experiment. I therefore dried one
hundred and fifty in the fun, and afterwards
planted them in three pots, fifty in each,
taken from feparate gourds. But the latenefs
of the feafon, it being the loth of October,
the conftant rain, and the coolnefs occa-
fioned by it, circumftances unfavourable to
vegetation, obliged me to place my pots in
a ftove, which, though it was not heated,
was kept warm by a contiguous chimney*
The event did not by any means correfpond
to my expecftation ; I took it for granted,
that none of the feeds would germinate, and
yet they almoft all came up very well. On
the 15th, ten days after they were planted,
' thirty-feven, out of one hundred and fifty,
had germinated i the number increafed daily,
infomuch, that on the 8th of November,
one hundred and thirty-three appeared above
the mould in the pots. I was unwilling to
leave the feventeen feeds that did not (hoot

unexamined ;

35^ DISSERTATION 111,

unexamined ; I found that they were eithei"
empty, or that the lobes and the plantules
were vitiated ; that is to fay, crifp and
v/ithered, becaufe they were unripe.

I referved the remainder of the feeds for
another experiment to be made the following
fpring. Before it can be aflerted that fruc-
tification has been complete, it is neceffary,
according to the determination of botanifts,
not only- that the feeds iliould grow, but
that they fhould alfo be capable of bringing
produdive feeds, or, in other words, of per-
petuating the fpecies. That I might learn
whether the feeds of my three gourds enjoyed
this prerogative, I caufed fome of them to
be planted in the fame place in May 1778,
and when they were grown to fome fize,
they were, as in the foregoing experiment,
carefully ft ripped of all their male flowers,
one female flower only being left upon each
individual. Thefe flowers were furnifhed
with fmall gourds, which grew ripe towards
the beginning of autumn, and the feeds they
produced grew I'uft as well as the former;
nor can I doubt that they would have
brought forth fruit juf!: as well, if I had

o

chofen to try them.

From thefe fads it appears, that the gourd
with ihield-form fruit does not agree with

bafil

DISSERTATION III* 353

bafil in the circumftances attendin^Tf senera-
tion. The feeds of bafil, to be produdive,
muft be impregnated by the pollen, but the
feeds of this gourd propagate the fpecies
without fuch help. The things which I have
related furnilh the moft certain and unequi-
vocal proofs of this affertion. It is im-
pollible to fufped, that the pov/der of the
male flowers, grov/ing upon the fame plant
with the female flowers, had any fhare in
producing this effect, becaufe I defliroyed
them long before it was ripe. Nor can it
reafonably be prefumed, that any pollen was *
carried by the air to the fpot from places at a
difl:ance, I purpofely chofe Scandiano (xx),
as there was not a gourd of this fpecies any
where in the neighbourhood. We mufl
therefore of neceflity conclude, that neither
the embryos of this plant, nor its frudifica-
tion, depend upon the powder of the fta-
mina.

XXII. I now come to the other fpecies of
gourd, the fecond plant, with male and fe-
male flowers growing feparately on the fame
individual of v/hich I propofed to treat (xx)*
One root of this fpecies was planted late in
the fpring of 1779, in the fame garden
which the two preceding years had produced
the g9urd with fhield-form fruit. The pre-
VoL. II. A a, fent

;J54 DISSERTATION 11X2

fent plant was in like manner deprived of all
its male buds, as foon as they began to ap-
pear, and a few female flowers only were left
for frud:iiication, fuppoflng it fhould take
place in tbefe circumftances. That this plant
might be infulated, and that no fufpicion
might arife concerning the influence of ad-
ventitious pollen, I took another precaution,
which he w^ho is aware of the delicacy re-
quifite in fuch experiments will not regard as
unneceiTary^ My precaution confifted in en-
clofing', in large bottles of glafs^ thofe
branches of which the female flowers were
about to open;, and fo to lute the necks with a
thick cement, as to prevent the paffage of
the external air, which is thought by many
to be the vehicle of the fecundating powder,
into the bottles. This contrivance eafed my
mind of another apprehenfion. Some bota-
nifts pretend, that the fecundation of feveral
plants is effected by means- of infedls. Ac-
cording to them, bees and other wdnged in-
fects of the fame kind, by creeping into-
flowers to fuck the honey, or extradl the wax,
are apt to brufh away the dull: of the itamina^
and to convey it on their bodies, from flower
to flov/er; in this manner, fay they, are
plants frequently impregnated. The in-
ftances of artificial fecundation, which will

be

Dissertation lirr 355

be hereafter mentioned, incline me to admit
this fuppofition. The difpofition of the
bottles in the manner above defcribed, not
only precludes all fufpicion of pollen being
conveyed to the female flowers by the air,
but it likev^ife hinders the accefs of infed:s«
Two female flowers about to expand, were
guarded in this manner by bottles wuth wide
bellies ^ but the bloflx)ms, as well as the
young gourds belonging to them, came to
nothing. The caufe of this failure was the
perfpirable matter ifliiing from the two en-
clofed branches: it colledied at firfl in the
form of dew upon the infide of the bottles,
and afterwards ran down in little ftreams
upon the flowers; hence they periihed in
three days. But the unfuccefsful termina-
tion of this trial did not caufe me to abandon
my purfuit ; it only taught me how to enfure
fiiccefs* I had only, as appeared from the
event of this experiment, to prevent the
flowers from relling upon the fide of the
bottle. I therefore contrived to fufpend
them in the middle, fo that they m.ight be
only jufl: as much moiftened by the perfpirable
matter, as v/ould be futRcient to keep them
in a ftate of vigour. In this manner two
female flowers were enclofed for eleven
days; that is to fay, from the time they were

A a z about

3^6 DISSERTATION III.

about to expand, till they were withered.
In the interval the fruit had grown a little.
Having thus eafed my mind of fear, left any
unperceived pollen iliould have been conveyed
to them at this moft critical period, I re-
moved the bottles on the twelfth day, and
expofed the fruit to the open air till it grew
ripe, which happened about the eighth of
September. They both fecmed perfeft; and
all the in fide of the feeds was occupied by
the lobes and plantule. The growth of the
feeds of the former fpecies gave me fome
reafon to hope, that thofe on which I was
employed would produce plants; and fo it
really happened : I planted an hundred, fifty
taken from each pumpkin, of which eighty-
nine were productive, and confequently
eleven failed : the caufe of their fterility was
the fame as in a former experiment (in which
feventeen feeds of the other pumpkin proved
unprodudlive (xxi). The plantule or the
lobes laboured under fome vice of organiza-
tion ; a circumftance by no means furprizing,
fince it is alfo obferved in the feeds of the
fame plants, when left to the care of Nature.
I planted the feeds of the prefent fpecies in
1780, as I had before fowed thofe of the
former in 1778; in both cafes the refults re-

• lative

DISSERTATION III, n^y

lative to frudlification were exactly alike. It
was therefore reafonable to conclude, that
frud:iiication in this plant does not, in the
fmalleft degree, depend on the powder of the
ftiimina^

A a 3 CHAP-

358 DISSERTATION IIi;

CHAP, IV,

generation of certain plants pro-*
ducing male and female indivi^
viduals5 on which the fecundat-^
jng dust was prevented from ex^

|:rting its influence, viz. canna-
bis SxlTIVA, HEMP, SPINACIA OLE-.
RACEA, SPINACH, MERCURIALIS AN-
NUA, ANNUAL MERCURY. -

XXIII . y^ANNABIS Sativa, hemp,
V->< During my relidence at Scan-^
diano, in the fummer of ij6j^
I obferved two phenomena, which deeply-
engaged my attention. The firft took place
upon a ftalk of hemp, that fprung up fpon-
taneoufly in my garden. It was ftrong and
tall, and on all fides furrounded by a wood of
branches. It produced a great number of
feeds, which, in all appearance were per-
fedly formed. I found, by experiment, that
they were.produftive, notwithftanding it was
the only plant in the garden which is very
large, and no male plants grew within a con-
fiderable diftance* Prejudiced as I was in

favour

DISSERTATION III, ^50

favour of the univerfally received fexual fy-
ftem, I felt feme flight fufj)icions arife in my
mind from this obfervation ; I could not re^
frain from mentionino; it as a finrular occur-
rence to feveral friends, and among others to
the celebrated naturalift Campi Somafco. I
however at that time thought, that the phx-
nomenon might be explained, from the fup-
pofition of pollen conveyed by the wind from
the hemp-yards, with which the marquifate
of Scandiano abounds — more efpecially as I
was aware of the great plenty of this powder,
which rifes in a thick cloud, when the plant
is fhaken. I imagined alfo, that from the
greater abundance of pollen aiibrded by the
male hop {a), the favourers of the fexual
fyftem, might account for the fruclificatiou
of female plants difcovered in places where
there are no males.

'XXIV. The fecond ph^nom.enon w^hicii I
obferved the fame year, was the following.
The inhabitants of the territory of Re^2:io
and. Modena, eradicate all the male indivi-
duals from the hemp-yards, about the fecond
or third of Auguft, and leave the females till
the end of September. In a feafon favour-
able to vegetation, the females continue to
grow above a month, and to produce new

[a) Hamulus Lupulas. Linn,

Aa 4 branches.

360 PISSERTATIOIJ III.

branches. Upon thefe branches fpring
flower-buds, which in time expand and bear
feeds. Of fuch female individuals I faw,
for the iirft time, great numbers growing on
the 8th of September, 1767; that is, thirty-
fix days after the male plants had been pulled,
as I was allured by a perfon of credit. I
fixed my attention chiefly upon the late
branches, on which as yet" the firfl: rudiments
of the ciofed flowers fcarce began to appear :
I moreover tied a thread loofely round them,
that I might try whether the feeds, if any
fhould be produced, would arrive at perfec-
tion. This a(^ually happened, as their
fhooting foon after I fowed them in October
irrefragably proved. This fecond phasnome-
non gave rife to ferious refledlions, as I could
not poflibly at firfl: comprehend how the pol-
len could have fecundated thefe female
flowers, which made their appearance upon
the branches fo long after the removal of the
male plants. After a little conflderation, I
perceived that the advocates of the fexes
might find fomewhat to adduce in their de-
fence. Notwithftandine the want of male
flowers, it might be faid, the pollen which
had been flied in fuch abundance, may float
in the air furrounding the individuals of the
other fex.

XXV,

DISSERTATION HI. 361

XXV. Eight years afterwards, in 1775, a
Memoir appeared in Rozier's Journal on the
fecundation of plants, the tenour of which
perfe6lly agrees with my obfervations on
hemp. The fubftance of this memoir, as
far as it relates to our prefent enquiry, is the
following. The author reared a female ftalk
of hemp in a pot at Paris, which produced,
at the ufual time, feeds of the common fize,
confifting of two well nouriihed lobes with
plantule or germ. When the feeds were
planted, they all without exception germi-
nated, and grew up in a fhort time. The
plant had not been covered by any thing; it
flood upon a window level with the ground,
at a great diftance from other plants of the
fame fpecies. The maker of this expew-
ment does not pretend, that it entirely ex-
cludes all fufpicion of the fecundating duft,
but only that the accefs of it is highly im-
probable ; he exhorts naturalifts to repeat
and improve his experiment. The author of
the Memoir does not make himfelf known
any otherwife, than by the initials M, F, de JS,
which feveral have fufpedled to deiign the
celebrated Mr. Fougeroux de Bondaroi, of
the Academy of Sciences, nephew to the iU
juftrious Duhamel. However this may be,
it appeared to me when I read the account,

that

3^2 DISSERTATION III,

that this delicate experiment had not been
conducted with fo much attention and fuch
precautions, as to produce convidlion in the
mind of the reader (a),

XXVI.

{a) Having communicated in a letter, written Sept. 18,
?777, to my illuilrious friend Mr. Bonnet, Tome refults relative
to the fecundation of plants, I received a very polite reply,
dated Nov. 29, the fame year. Among other things he men-
tioned this Memoir, fuppofmg I had never feen it. It was his
opinion, that the obfervation of the French Naturalift, whom
lie prefumes to be Mr. Fougeroux, is not fufficiently deciiive
ta exclude the fecundating powder. He was induced, by his
refpeft to truth, to make fome ftridures on different paflages
of this Memoir ; which, as they are conne<5led with my ob-
fervations on generation, it will be proper to tranfcribe.
** Various indadvertencies and miftakes have been committed
"l>y M. F. which might be overpailed in an author of inferior
reputation. I ihali point them out from a fhort account I gave
to another correfpondent. The propofitions diftinguiihed by
Italics are the wards of M. F.

** We are not Jure ^ that the chicken exijis before impregnation
in the egg, and n.ve mujl confequenily he ignorant , ^whether the
flant exijis in the feed before fecundation,

** The learned naturalift ought, I think, to have expreffed
himfelf very diiferently after the fine difcovery of Halier, of
the pre-exillence of the chicken, after your^s of the pre-ex-
iilence of the tadpole, and Mr. Muller's and my obfervations
on the pods of peafe. ■ Palingen, T. !. p. 416. In my eiTay
on the fecundation of plants, printed in Rozier's Journal, for
OSt. 1774, I had brought to the reader's recolleclion thefe fe-
deral difcoveries on vegetables and animals, as ftrongly tending
to eftablifli the great probability of the pre-exiftence of the
germ ; and M. F.'s Memoir evidently refers to mine.

** But is fecundation, by means of pollen, necejfary in all
plants ? Ha've none their parts of generatisn concealed, like thg
ike of plants {pucerotiA ?

<' The

DISSERTATION III. 3^3

XXVI. In relating my fubfequent experi-
ments on the generation of plants, I fhall

give

*' The parts of generation ia the lice of plants are not con"
(ealed. On the contrary they are quite obvious. I dwell pretty
largely on the amours of thefe infeds in my Infedclogy pub-
iiflied in 1745. -'■ ^^^^ defcribe at length their genital organs.

** Laying ajide all fyjlematical ideas j I abide by fa£is and
obfer vat ions t and foil onjo a celebrated guide, M. Duhamel, 'who^
before me, has tnultiplied fads and obfer-vations, '■without 'ven"
turing to decide.

*' It is doubtlefs commendable to abide in phyfics by fads
and obfer^ations. But found logic more than barely allows us
to deduce the moft immediate and dire6l confequences, as I
have endeavoured to do in my works, and in the eflay which
Mr. F. feems to have held in view. He expreffes his intention
to take Mr. Duhamel for his guide But the fine difcoveries
of Haller, Spailanzani, &c. were unknown to Mr. Duhamel
when he compofed his excellent Natural Hiftory of Trees,
which was publiihed in 1758. Mr. F. who publifhed his Me^
moir in 1775, was naturally called upon to weigh the confe-
quences refulting from thefe difcoveries, and to avail himfelf
of the analogical dedudions drawn by me refpeding vegetables.
This, however, he has not done, and I cannot but be fur-
prized at it.

*' ^hofe -who fuppofe the plant to exiji in the feed befort fe-
cundation, confder the pollen as co,?fJiing of a. number of fneaths
and cafes, of --which each contains a. number of feeds floating in a
thin liquor.

" Some naturalifts, as Needham, have confidered the pow-
der of the llamina in this light, but they do not allow the plarits
exijlence in the feed before fecundation. Mr. Needham who fo
well explained the compofition of the pollen, believed the germ
to be in the pollen itfelf. Mr F. has therefore expreffed himfelf
very incorredly ; but when He immediately afterwards fubjoins,
the plant, according to this opinion, exifts before fecundation in
the povjder of the jiamina, he fails into the moft glaring con-
tradiction*

3^4 PISSERTATION iir.

give an account of the means employed to
prevent the accefs of the pollen. Six fmall

flalks

tradiflion. ^hat the plant exifts in the feeds before fecundation ,
is an hypothecs which excludes the opinion, that the plant exijis
before fecundation in the po'vjder gf the flainina.

** But here only human intelleQ is be^-wildered. Hoiv can ^we,
iijlng cur reafon^ imagine the germs of all plants to be inclofed in
fuch a germ. What an abyfs ! Let us quit this clue as likely tot
mijlead us,

" What meaning has the word only in this place : It is pre-
cifely by the ufe of our reafon which does not imagine, but
ioncei^e, that we perfuacje ourfelves of the probability of that
hypothecs, according to which germs are inclofed one within,
another. If M. F. had rqad my Memoir more attentively,
and refle£led longer on the fubjeO, his mode of expreffiori
would have been more philofophical. Does it then belong to
the imagination to decide concerning matters lying exclufively
within the province of reafon ? Can the imagination reprefent
to itfelf an animalcule many million of times fmaller than a
fniteP Can it reprefent to itfelf a globule of light, feveral thou-«
f^nds of which fall at once on the eye of fuch an animal ? No;
never will reafoning or calculation overturn the hypothefis of
in^-volution. Great and fmall are merely relative terms ; and
we are acquainted with furprizing fadls that lead us to this hy-^
pothefis.

'' According to Haller, irrii ability is the prificiple 'which CQn->.
flitutes animality and produces life. The ponvder of the Jiaminci
exciting the irritability ^ and occajtoning the fluids to be impelled
in the organized body, produces in the 'vegetable the fame effects
as the fpermatic liquor in the animal germ.

*' Haller did not admit irritability in vegetables. He could
not therefore attribute to the powder of the ftamina thaty?zV««-
lating property which he acknowledges in the fpermatic liquor
of the animal: and yet, from M. F.'s expreflion, it would be
fuppofed that he does. But it was I, who, in my eflay on the
fuiindation of plants, fought to apply irritability to the fe^un*

dation

DISSERTATION III. ^^^

ftalks of hemp were tranfplanted from aa
hemp-yard into fix pots. As foon as they

had

Nation of vegetables — not, however, till I had declared my
ignorance of any fa6l which rigoroufly proves the exiftence of
irritability in the vegetable kingdom. Upon this occafion, I
threw out fome logical refledlions, calculated to caufe the fuf-
penfion of the reader's judgment. Let me be allowed to ob-
ferve, that no author in natural hiilory has been more careful
to dilHnguifh conjedlures from fafts : but I do not believe that
conjedures are unwarrantable. I have therefore confined my-
felF to fliew how we may conceive the influence of irritability
in vegetables, fuppofmg them to poflefs this property. M. F.
read me too rapidly, and without reflecting fufiiciently upon
my mode of arguing. Moreover, the irritability of plants
which I did but conjedlure to exift, feems to have been well ob-
ferved by the celebrated Gmelin in fome fpecies ; but I was
unacquainted with his obfervations in September 1774, when
1 was compoflng my efl"ay. That author, in his Difl^ertatioa
on Irritability, Ihews, that the antherae, or fummits of the
ftamina, appeared to him irritabky or at leafi endo'vjed nvith a
property nearly approaching to the property of animals called irri-
tability. He adduces many in fiances exceedingly remarkable,
and, among others, that of the orchis. 1 he anthers of this
plant, he obferves, recently gathered, and irritated in a ^varm
place, appeared to contrad, and then to relax, and to undergo a
kind of tr emulation. He adds, that he has frequently made the
experiment, and that it alnuays fucceeded.

'* According to Mr, Bonnet, the feminal fluid, in producing
impregnation, effects only the^^olution of <vjhat -Mas already
formed.

•* This certainly is my opinion : but to fay fo much is faying
nothing ; for fuch vague expreflions do not ferve to diliinguiih
my notions from thofe of other naturalilts who rejedt the do(Srina
of Epigenefis. I have reafon to preiume, that the worthy
M. F. has not ftudied with any care the nature and the con-
nexion of my principles on generation. He was doubtlefs too

much

366 DISSERTATION III.' .

had attained a certain height, and the male
plants could be diftinguiihed from the fe-»
males, the former, v/hich were four in num-
ber, were eradicated, and the two females
only were prefer ved. About twenty days
before they began to flower they were carried
into a room looking towards the fouth, v/here
they ftood forty-two days. There were twa
windows in the room, which were always
kept fhut, as alfo was the door, except when
I went in to water the plants. They thrived,
notwithftanding their confinement, on ac-
count of the rays of the fun fhining through
the windows upon them feveral hours a day.
Although this precaution feemed preferable
to that of the French anonymous writer,
who had placed his female plant -upon a

jxiuch prejudiced with the idea of generation being a myftery
not yet penetrated by the ablefi naturalills. God forbid that I
Ihould have the prefumptioji to think that I have dr^wn afide
the curtain that covers the myftery : I have only attempted to
lift up a corner of this curtain.

** When ixie read the opinions of moji natufalijisy do n.ve not
incline to, belie'vey that each, out of affeBion to his onvn ideas,
jlattets himfelf that he, has dinjined the fecret of Nature ? »

** I muil confefs that there are phyfiologifts and natural hif-
torians who defer ve this reproach ; but there are others who do
not deferve it ; and M. F, ought to have excepted them. Yoa
have read me, and, what is more, have ftudied me. You,
therefore, know whether 1 have ever propofed my notions as a
many --who fiattired himfelf that he had di~ji?ied the fecret of
Nature.''

windoW;,

DISSERTATIX)N IIT. ^6j

window, it did not fatisfy me. The pollen
indeed fuppoied to be difleminated through;
the air at the flowering of the hemp-yards,
could not very readily find its way into an
apartment kept fo clofely fliut, yet it cannot
be alierted that its ingrefs was totally pre-
vented; and yet it was of the utmoft import-
ance to hinder it, at leaft, from coming in
contact wdth the flowers. To attain this
end effedually, when I brought the pots
into the room I immediately introduced two
branches of my two plants, upon which
fome buds were growing, into two glafs
bottles, with long necks and large bodies.
The necks wereperfed:ly clofed with cement,
without injuring the branches. By being
perfectly clofed I m^ean, that all communica-
tion between the external air and the inlide of
the bottles was cut off, as was evident from
the following decifive proof. Along with the
branch of hem.p, I inferted, for about five
inches, an open tube of glafs, w^hich was
imbedded in the cement; the other end pro-
jected four feet from the neck of each bottle,
and was immerfed in a bafon of water to the
depth of feveral inches ; but I had firft taken
care to fuck a portion of air out of the bottles.
The water afcended to the height of a foot
■and three quarters into the tube, at which it

conilantly

^68 DISSERTATION III.

conftaiitly ftood, being only fubjedt to fuch
variations as are obferved in barometers, for
the tube was now actually changed into one
of thofe inflruments. The permanent ele-
vation of the water in the tube was a certain
iign, that no external air found its way into
the bottles : had a ftream of air made its
way through the cement, or any part of the
bottle, it is obvious, that the water in the
tube muft have defcended to the level of
the bafon. I muft own, indeed, that I was
obliged to renew the experiment feveral times
before I fucceeded. With this apparatus I
was certain that the external air, and con-
feqilently that the pollen, which may be
fuppofed to be difperfed through it at the
approaching flowering of the hemp-yards,
could find no accefs to the confined
branches.

xxvii. But all thefe precautions feemed
infufiicient to render the experiment quite
unexceptionable. It was neceflary, not only
to remove all fufpicion of external pollen
getting into the bottles, but likewife to
watch whether any of this powder was pro-
duced within. The botanical reader imme-
diately comprehends the reafon of my appre-
henfion. It has been obferved by Linn^^us,
Haller, Duhamel, and others, that male

flowers.

DISSERTATION 111. 3^9

flowers are not very infrequently found upon
female individuals : a root of fpinach, of
which I fliall fpeak below, furnifhed me
with a remarkable inftance ; and the fpecies
in queftion is fubjecft to the fame accident, as
I was informed by Mr. Bonnet, in a letter
dated Augufl 15, 1778* The letter gave
me notice of an experiment which he under-
took upon hemp, after I had communicated
mine to him. The paragraph to which I
allude is the following : ** I began this year
fome experiments upon hemp. I have fol-
lowed the method which I employed for
rearing the lice of plants in folitude. My
plants were covered with large tubes of glafs,
hermetically fealed at the top, and with the
bottom funk in the earth. But fortune did
favour me — inftead of a female I had a
male plant in one inftance, and in another a
plant of great expedlation, after putting forth
many flowers with piftils, produced fome
with ftamina, clofe to the former, which
totally difconcerted the experiment.'' It
therefore became me to watch diligently,
whether any male flower was produced
among the females; I therefore carefully
examined twice a day, both with my naked
eye and a glafs, the confined branches, which
were as open to infpedlion, as if they had
Vol, IL B b been

^70 DISSERTATION III.

been growing in the open air. In the meart
time, I did not neglect the other parts of mjr
two plants. That the examination might be
more certain, I ftripped off all the branches
except thofe which were inferted into the
giaffes, and took care to infpe(ffc the ftems as
clolely as the branches. But I can aflure the
reader, with the utmoft confidence, that
the flowers which fucceffively made their ap-
pearance, both on the bare ftems and
branches, were all female without a fingle
exception. For the fake of perfpicuity, I
will firft defcribe the trunks, and then the
branches. The former began to put forth
their flowers towards the end of Auguft, at
which time the hemp-yards were alfo in
bloom. Notwithftanding their conftant con-
finement, they produced feeds, and ripened
them by the end of September. When I
compared thefe feeds with fome which I
gathered in the hemp-yards, I found that
they were fmaller. Befides the number of
feeds produced by the ftems in the hemp-
yards, were in like circumftances confiderably
more numerous, than by the two ftalks con-
fined in my apartment. But notwithftanding
thefe differences, the feeds grew nearly as
well in the apartment as thofe which grew in
the open air, as I found by fowing feveral
, . hundreds

DISSERTATION HI. 371

hundreds of both forts; Such are the refults
afforded by the two flems.

XXVIII. I am now to relate what happened
to the two branches. The flowers, which
nearly kept pace with thofe of the trunks,
were fucceeded by feeds ; towards the 20th of
September they had acquired fuch a fize, as
inclined me to think them ripe; I therefore
refolved to take the branches out of the
bottles, and I found in fadl, that more than
^ an hundred v/ere arrived at maturity; this
was doubtlefs in fome meafure owing to their
having received no moleftation from the per-
fpirable matter, which was collected in large
quantities in the belly of the bottles. By
dilTe(fling fome of the ripe feeds, and others
that were more or lefs diftant from this ftate,
I was enabled to make the following obfer-
' vations: When the parts furrounding the
leaft forward are removed, a greenifli pyri-
form body prefents itfelf with two points
like fmall antennae, which are the rudiments
of the piftils. In the pyriform body is con-
tained a folid nucleus, femi-gelatinous, and
confifting of an homogeneous fubftance.
The nucleus in feeds further advanced, ex-
hibits an excavation in the center, full of a
liquid which, in feeds yet nearer mat^urity,
is thicker ; and in this infpiffated matter may

B b 2 be

372 DISSERTATIOH 4ll.

be jfeen a white point, which is eafily known
to be the lobes and plantule. If feeds ftill
more advanced be analyfed, in opening of
the lobes, which are bent into the fhape of
an arch, a cavity or depreflion is obferved,
and in it are lodged two whitifh dentated
leaves, which are inferted in the plantule, or
rather arife from it. Thefe leaflets are larger
in ripe feeds. Such were the appearances of
the product of the branches; and feeds ga-
thered in the hemp-yards furnifhed me with
the fame obfervations. Hence I was obliged
to infer, that Nature, in the producSlion, or
to fpeak more properly, in the evolution of
the feeds, had operated alike in the clofed
bottles, and in the open fields.

I faid before, that the feeds of the two
confined ftems were fmaller and in lefs
number, than of thofe in the hemp-yards.
I may now add, that the fmall fize of the
feeds that grew in the bottles was ftill more
remarkable, and that equal branches ufually
produce twice the number. But I fhall be
alked, did feeds (o much finaller and lefs
numerous grow when they were fown. To
this curious and important point all my en-
quiries tended. Of a hundred and fixteep
feeds, which were all that feemed to be ripe,

one

DISSERTATION III. 373

one half, viz. fifty-eight, were fet in a pot,
and they all, except five, came up.

XXIX. The refult of another experiment
correfponded perfectly with the foregoing.
Though a large quantity of pollen arifes from
the hemp-yards into the atmofphere, at the
feafon of flowering, and is tranfported to no
inconfiderable diftance, it is reafonable to
fuppofe, that in the courfe of feveral months
it muft be loft ; for the rain and fnow cannot
fail to carry it down to the ground, and free
the air from it : fhould any continue to float
in the atmofphere, it will probably in time
lofe its prolific virtue. This fuppofition,
which feems well founded, as will be more
particularly ihewn in the fucceeding chapter,
induced me to make fome female plants of
hemp blow before the hemp-yards were ia
flower. With this view, I fet at Pavia
twelve hemp-feeds in twelve pots, before the
middle of November -, the feeds were fome
that remained of the produd: of the confined
branches (xxviii). Although the feafon
was unfavourable to vegetation, eleven out
of the twelve germinated,, and continued to
grow, though but flowly, the whole winter,
the pots having been removed into a warm
room. When fpring arrived, the windows
were thrown open, and left fo till I had oc-

B b 3 cafiOA

374 DISSERTATION III.

cafion for the plants. Meanwhile they con-
tinued to advance, and about the 20th of
May, the male and female individuals could
be diftinguiflied. The former were deftroyed.
The remaining fem.ales, four in number,
were expofedto the air and fun on the outfide
of a window. That I might examine with
greater eafe and certainty, whether any male
bloffoms were produced upon thefe female
plants, I cut away all the branches, and
preferved only- the flalks, as in the experi-
ment related in the xxviith paragraph. But
fortunately no fiowxrs of this fort ever ap-
peared. Towards the end of May, flowers
'with piilils began to appear, fix weeks before
the flowering of the hemp-yards beyond the
Po (for there is no hemp raifed in the neigh-
bourhood of Pavia) and confequently before
the diffemination of the frelh pollen. About
the 8th of June moft of the feeds were ripe.
They were quite as thick and large as upon
the f!:ems reared in the fields ; I fowed feveral
hundreds, and molt of them germinated.
One immediate confequence may be deduced
from thefe variations of my experiment.
The perfed frudiiication of hemp is entirely
independent of the action of the fecundating
dufl.

XXX. But

DISSERTATION III. 375

XXX. But enough of the experiments on
hemp. I proceed to Ipeak, but much more
briefly, of fpinach (Spinacia Ok race a). I
made feveral different trials with this plant in
the courfe of fome years.

In the firft place, I tranfplanted in May
feveral roots into my garden at Pavia. As
foon as the different individuals could be dif-
tinguilhed, 1 deffroyed the males. The fe-
males, although they remained alone in the
garden, produced plenty of feeds, which,
when fown, germinated in great abundance.
At the time of flowering, I v/atched with
great care, whether any blofibms with ftamina
opened : my illuftrious colleague and friend
Counfellor Scopoli, alfo examined my fpina-
ches; but neither could that expert botanift
or myfelf perceive any.

I next covered a plant of fpinach with the
receiver of an air-pump ; the lower end was
preffed to fome depth into the earth of the
pot. Thus the communication between the
external and the internal air was cut off, un-
lefs the former may be fuppofed to have found
its way into the receiver, through pores in
the mould. I made ufe of this apparatus a
.tew days before the opening of the flowers.;
but was obliged, in thirteen days, to remove
the receiver, for the leaves began to wither,

B b 4 probably

37^ DISSERTATION III.

probably on account of their confinement.
Several flowers with piftils had in the mean
time fet, and the appearance of the feeds
promifed that they would do well ; nor was I
deceived in my expectation, for they ripened
perfedly, and when fown, came up in great
abundance.

XXXI, In the Modanefe and in the Mar-
quifate of Scandiano, the fpinach raifed by
the people of the country, is ufually in flower
from the 20th of May to the middle of June,
fo that the feeds are commonly gathered at
the beginning of July. I took advantage of
this prad:ice to procure piflilliferous flowers,
a long time after the bloflbms with ftamina
had decayed. For this purpofe, I fowed
fome fpinach towards the end of May ; the
female plants produced flowers with pifliils in
September, and many of the feeds came to
maturity ; but many others were checked by
the beginning coldnefs of the feafon : but
thofe which grew ripe were fown, and they
germinated. Notwithflanding, therefore, near
lix weeks had elapfed fince the falling of the
flaminiferous flowers in the fields and gardens,
my feeds were produdtive. It is difficult to
imagine, that the pollen could have been the
caufe of this fecundity; and the rather, fince
iti fpinach it is far from being in fuch

abundance.

DISSERTATION III. 377

abundance, as to be capable of diflemination,
like that of hemp, far and wide through the
air. My fpinaches were, moreover, con-
ftantly kept in an apartment.

XXXII. I neverthelefs undertook another
trial, which I believed would be decifive.
I had feveral young fpinaches tranfplanted
into pots in Auguft at Pavia, one into each
pot. Great attention being paid to them,
they grew before winter to a coniiderable
height. And being kept in a warm room,
they made fome further progrefs during the
courfe of this feafon ; and before the end of
March, the female plants, which were three
in number, began to put forth flower-buds
with piftils. But here an accident, which
is not very uncommon, and to which I have
already adverted (xxvii), occurred. In one
of my daily vifits to my three plants, I per-
ceived upon one individual an unexpecfted
conjundlion of male and female flowers, grow-
ing clofe together, and forming very elegant
groups.

The bloflx>ms with pifliils were very confpi-
cuous, but thofe with fl:amina w^ere fo little
advanced, that they could not be difl:ingui£hed
by the naked eye. Both forts appeared to be
equally numerous, but the union extended
only to two branches— all the refl: bore fe-
male

37^ D I^ S S E R T A T I O N III.

male bloffoms only. I may here incidentally
remark, that the great abundance of the
male flowers, in the prefent cafe, is a very
Angular phasnomenon. I have read in bota-
-nical writers, that a few male flowers are
fometimes found in company with females,
but never that they amount to an equal
number, a circumflance that excited my ad-
miration with refpedt to this individual; for
I counted two hundred and feventy-five male
buds,. This unforefeen accident determined
me to extirpate the plant. I confider it as
very fortunate, that I obferved it in time,
while the male bloflbms were yet in a very
immature fl:ate, and confequently before the
pollen could yet have produced any effedt.
Having thus freed myfelf from the trouble
of watching this extraordinary individual, I
continued to obferve the two others 5 they
produced only bloflbms with pifl:ils. April
was the fsafon of the maturity of thefe blof-
foms, which is generally efliimated by their
aptitude to be fecundated: it was earlier by
thirty-five days, than the ufual flowering of
this plant in the environs of Pavia. Before
the end of May, the feeds of my two plants
were almofl: all ripe. Every branch and
every twig was loaded, and they were of
equal flze with the feeds produced in the

neighbouring

DISSERTATION III. 379

neighbouring gardens the preceding year.
To complete the experiment, it remained to
try whether they would germinate. Of a
hundred and fifty, chofen among the whole
produd; as the fineft, a hundred and thirty-
two came up ; and of a hundred, which I
afterwards fowed, ninety-three grew. Thefe
proofs obliged me to conclude, that the feeds,
notwithitanding the privation of the pollen,
were produdtive.

XXXIII, The next and laft plant producing
male and female individuals, which I men-
tioned, is annual mercury [mercurialis an^
7iud), Five very fmall plants were removed
from a garden, on the 2 2d of Auguft, into
five pots. They were managed in the fame
manner as the fpinach during the winter
{xxxii), and were all fo far advanced at the
beginning of fpring, that there was no diffi-
culty in diftinguiihing the males from the
females ; of the latter there were three, and
thefe alone were preferved. By the 24th of
March bloffom.s with piftils appeared upon
feveral branches, growing out of the axillae
of the leaves, and in a few days more the
number was exceedingly increafed. They
were borne upon fhort flower-flalks, and, as
ufual, confifted of two fmall feeds refqinbling
tefticles. They were of a green colour and

hairy.

3S0 PISSERTATIOK IIi;

hairy. But here the event was jufl: contrary
to what happened in hemp and fpinach.
The greater part of the bloflbms dropped
prematurely ; of the few that remained the
feeds grew for fome time, but fell before they
were ripe, and when fown, they did not
fpring. As this took place before the male
plants in the gardens and the fields about
Pavia were in flower, I began to fuppofe
mercury to be one of thofe numerous vege-
tables, which cannot propagate the fpecies
without the powder of the ftamina. Mean-
while my three plants continued to put forth
new branches, and the old ones, inflead of
withering, vegetated with great vigour; but
ftill the feeds dropped prematurely. This
gradual evolution and production of frefh
branches, was of fuch long continuance,
that they fhewed no tendency to decay, but
were producing blofToms with piflils when
the mercury in the fields was in flower. I
therefore began to entertain hopes, that the
feeds now put forth, and thofe which fhould
follow, would fucceed better than the earlier
feeds, more efpecially as the pots were ex-,
pofed to the open air upon a window, and
looked into a garden, in which grew feveral
male individuals of this fpecies. But my
expedations were dilappointed : as long as

the

DISSERTATION III. 381

the three plants continued to thrive, the feeds
dropped almoft as foon as they appeared -, nor
did one of thofe that were fown ever cpme up.
I repeated the experiment two fucceeding
years with the fame event,

XXXIV. It therefore became neceflary to
vary the mode of conducting it. Being more
confirmed in my fufpicion, that the fterihty
arofe from want of pollen, which, though it
was at no great diftance, did not reach my
plants, I determined to bring it nearer ;
without, however, fetting individuals of the
different fexes in the fame place. Two male
plants of mercury, reared the next year in
two pots, were placed on the outfide of a
window, and two females growing likewife
in pots, were fet on the outfide of another
window. Both windows belonged to one
room, and had the fame afpecl. The four
roots of mercury were nearly of the fame
age, and of the fame fize. And I waited
with great anxiety to fee whether the females,
on account of their vicinity, would be im-
pregnated by the males. The feeds were
conftantly falling, but not in fuch abundance
as in the former experiment, when the males
were at a much greater diftance (xxxiii).
Thofe which adhered went on thriving, and
feemed as if they w^ould ripen ; and they did

accordingly

2^2 DISSERTATION III.

accordingly arrive at maturity, and, what is
of more confequence, were produd:ive; for
foon aft^r I had fown them in a pot, I had
the pleafure of feeing them fpring. It there-
fore appeared probable, that the vicinity of
the males to the females had been inftrumen-
tal in occafioning fecundation : their in-
fluence could fcarce be derived from any
fource, befides the adtion of the contiguous
pollen.

XXXV. This experiment obvioufly required
another : it was oroper to brinor the different

JL i O

individuals nearer to each other ; I accord-
ingly placed two males and two females upon
the fame window. It now became manifeft^
how much influence the approximation of the
two fexes has upon fecundation. The- two
females retained almoit all the feeds which
w^ere produced at this time, exceeding an
hundred. The feeds grew perfedtly ripe, and
when put into the ground, were unfolded into
as many plants.

xxxv I. The females having feveral branches
in vigour, and fall continuing to vegetate,
an experiment, the reverfe of the two pre-
ceding, fuggefted itfelf to me. I removed
the pots in which the male plants grew into
another chamber. This feparation ferved
further to corroborate the necellity of the

pollen

DISSERTATION III. 383

pollen in mercury; for in confequence of its
entire removal, all the feeds afterwards pro-
duced, by the growing branches fell before
their time, and were unprodudive.

Moreover, it is by no means furprizing
that females, at a diftance from males, fhould
be fterile. The pollen is in too fmall a quan-
tity to be widely dilTeminated. The in con- .
fiderable quantity which was afforded by
feveral male plants, at a time when the an-
theras, viewed by the microfcope, appeared
full, gave me ample proof of its fcarcity.

I fliall make upon mercury another obfer-
vation, veryneceffary to be known. I have
informed the reader, that moft of the unim-
pregnated feeds wither and drop, while a fev^
grow to fome fize, but are not productive
(xxxiii). The fcope of my refearches re-
quired that I ihould examine, w^hether thefe
feeds confift of lobes and a plantule. By
analyiing them repeatedly, I found that the
feeds, which fall foon after the flowering,
are full of an homogeneous and gelatinous
fubftance, and afford no veflige of plantule
or lobes. But impregnated feeds, examined
at the fame period, that is to fay, a little
after the feafon of flowering, exhibited the
■fame appearances. Many days elapfed be-
fore the lobes and the plantule could be dif-

-cerned.

DISSERTATION UU

cerned, an obfervation that is not confined
to mercury, but extends to every plant hi-
therto examined by me. In thofe feeds
which made a tolerable progrefs in their
growth before they fell, appearances were
very different. They firft became full of an
almoft fluid whitifh matter, which was gra-
dually infpiifated; and in the midft of this
matter, after fome time, might be feen a
little body, fo foft as to adhere to the finger
when it was touched ; but it afterwards made
fome refiftance to the touch, and now evi-
dently appeared to be the lobes and plantule;
which parts grew more confpicuous and dif-
tind: as the feeds advanced. The plantule
had the fhape of a cone, dilated towards the
bafe into two flat circular bodies, which were
the lobes. The fame was alfo the figure of
the lobes and plantule contained in pi;odudivc
feeds.

CHAP.

DISSERTATION III. ^^5

CHAP. V.

RECAPITULATION OF THE PRINCIPAL
CONSEQUENCES OF THE FACTS RELAT-
ED IN THE FOUR PRECEDING CHAP-
TERS.

Reflection

s.

XXXVII. A LL thefe fa(fls convey, in my
-*'•*' opinion, inftruclion fuffi-
cient to ferve as a foundation for fpeculating
on the mode obferved by Nature in the gene-
ration of plants. If we infpedl the ovaria
before fecundation, we find the feeds ex-
ternally folid : they continue in this ftate for
fome time after fecundation. They after-
wards became hollow within ; in the cavity
appears a fmall body, not diftinguiihable at
firft, but afterwards known to be the embryo
or the plantule with the lobes. The embryo
fometimes feems detached from the feeds, and
floating in a liquid, and fometimes is attached
to them by one or more connecting threads

(ll, III, IV, V, VI, VII, VIII, IX, X, xi^
XII, XIII, xxxvij.

Vol, II. C c As

386 DISSERTATION III.

As thefe fa6ls feemed favourable to the
opinion of thofe, who fuppofe the embryos
of plants to . pre-exift in the powder of the
antheras, and thence to pafs into the feeds,
which therefore do not contain an embryo
before fecundation, I was led to turn my re-
fearches towards the pov/der. I examined it
with the microfcope, but could nqt by any
means find that the embryos, or any beings
analogous to them, are lodged in it (xv).
Hence I proceeded to the expedient of in-
terrogating Nature in another manner : I en-
deavoured to prevent the accefs of the im-
pregnating duft to the ovaria, fuppofmg that
fuch means would furnifh the clue to this
abftrufe myftery. Three defcriptions of plants
were fubmitted to experiment; hermaphro-
dites ^ thofe v/hich bear feparately upon the
•fame individual,, male and female flowers;
.and, laftly, thofe which produce both male
and female individuals. The antherae of
the firfl: were cut away before the ripening of
the pollen; in the fecond the male flowers
were extirpated, and the female individuals
of the third were infulated. In the herma-
phrodite plants it appeared, that the privation
. of the pollen does not prevent the appearance
of the embryo in the feeds, though the feeds
are incapable of germinating; in fome plants

the

DISSERTATION III. 3S7

the abfence of the pollen neither hinders the
embryos from appearing, nor the feeds from
being produ(^l:ive ; the fame obfervation is to
be applied to feveral plants with female indi-
viduals; but in other plants of the fame clafs,
the want of pollen renders the feeds fterile,
though the embryo appears in them, (xviii,

XlX, XX, XXI, XXII. XXVI, XXVII, XXVIII,
XXIX, XXX, XXXI, XXXII, XXXIII, XXXIV,

XXXV, xxxvi).

The dired; and immediate confequence of
thefe refults is obvious : for if the embryo
appears without the co-operation of the pol-
len, and if befides, in many cafes, the feeds
grow, it is clear that their exiftence can have
no dependance on the pollen ^ and upon thofe
occafions on which the feeds do not grow for
want of it, we can only fay, that they ftand
in need of the condition requilite for their
further evolution, as the fetufes of animals
do not thrive for want of feed, although
they pre- exiil in the ovarium of the female.
Another confequence not lefs evident is, that
as the embryos do not belong to the pollen,
they muil neceifarily appertain to the ova-
rium.

Some naturalifts, of no vulgar reputation,
.have fuppofed, that the em^bryos of plants are
formed by two principles, one contributed

C c 2 by

388 DISSERTATION Hi;

by the powder of the ftamina, the other by
the plftils. But my obfervations, which
prove that the embryo has no dependance upon
the pollen, clearly prove the falfehood of this
fuppofitiorir.

XXXVIII. But the embryo, which I have
iliewn to belong exclulively to the ovarium,
may be conceived to belong to it in two
ways. It may be formed of matter furnifhed
by the parent plant, or it may pre-exift.
Now, which of thefe ways are we to admit ?
An Epigenefift, a Count BuiFon, accuftomed
to view Nature under an angle proportional
to his favourite ideas, would not probably
heiitate, if the facts obferved by me had
paiTed under his infpecftion, to embrace the
former opinion. The embryo, not being at
iirfl: vilible in the cavity of the feeds, but
appearing afterwards in the form of a gelati-
nous point, without any determinate ihape,
floating befides, in a liquid without any per-
ceptible connedlion with the feeds, continu-
ing to grow and becoming organized in it —
Thefe arguments would no doubt be fufficient
to lead that famous naturalifl: into the belief
of the embryo's formation in the feed ; he
would perhaps alfo believe, that it is formed
of the liquor in which it floats. But if we
lay afide all prejudice in favour of any fe<51:,.

and

DISSERTATION III, 389

and apply the ftrift principles of logic:, we
fliall find thefe arguments inadequate. Jii
the firft place, that a liquor, or any other
inorganic fubftance, fhould nourifli and pro-
mote the growth of an organized body, is a
propofition eafily conceived, and is indeed
proved, by daily obfervations on ourfelves,
on animals, and plants. But it is not fo
eafy to conceive, that an inorganic and
fhapelefs body, whether liquid or folid, can
be organized by mechanical laws only : and
with all his eloquence, and by all imaginable
efforts, the naturalift above-mentioned has
never fhewn, that one animal, orone veg;e-
table, even among thofe that appear the leaft
perfeft, and the lea It organized, owes its
origin to a mechanical oppofition of parts.
Secondly, though the ernbryo does not ap-
pear to be organized, this is by no means a
fure proof that it is not. During the firft
hours of incubation, the organization of the
chicken is not perceptible ; and yet we cannot
doubt that it is orgazined, if it can be proved
to exift before fecundation. Now Haller
has given the proof of this wath refpecl to
the chicken; and I have given it with refped:
to newts, frogs, and toads. It is therefore
beyond all doubt, that thefe amphibious ani-
mals are organized before fecundation. But

C c 3 their

390 DISSERTATION III."

their organization is not then apparent; mere
appearances would lead us to fuppofe them
formlefs bodies ; for we fee nothing but
fpherules, confifting of a cover or fkin filled
with a femifluid ir.atter. The fame feem-
ingly inorganic ftru^lure continues for fome
time after fecundation. The embryos of
plants, then, may alfo be organized, although
they do not appear to be fo ; and I have cer-
tain proofs that this organization, though not
at firft apparent, is actually prefent. When
I Opened the feeds at the time the gelatinous
point began to appear in the midft of the li-
quid, and examined it without uiing any
method of preparation, I could difcover
nothing that had the appearance of being
organized; I faw neither lobes nor plantule,
nothing in Ihort but a mucilaginous particle.
But if I firft boiled the feeds, this point oftener
than once put on a different afped;. It was
not only no longer gelatinous, but when I
turned it about, and preiTed it gently wdth
the point of a needle, it would fometimes
fplit into two exceedingly minute pieces, in
the middle of which was implanted a pointed
atom : it w^as not very diiricult to difcover
that thefe parts were the lobes and plantule,
as v/as ftiil more manifeft when a microfcope
of great magnifying power was employed.

This

DISSERTATION HI. 39I

This point, therefore, proved to be organized
at a time when it was not fufped:ed; nor is
this the firll occallon, on which the a(il:ion of
fire has been ufed as a convenient method of
afcertaining the organization of a body which
had no fuch appearance. It is well known
to the cultivators of Natural Hiftory, that
the worms generated by thofe winged infecfts,
ufually called carrion fies^ after having ac-
quired, by feeding on putrefied fiefli, a proper
fize, are formed into an eloneated bowl, in
which the fly is gradually elaborated ; or, to
fpeak more properly, unfolded. If thefe
bowls be opened a few days after they are
formed, no lineaments of a fly prefent them-
felves to the fight ; we find only a kind of
pap, without any fign of organization. But
the fcene changes, if the bowls be boiled
at different periods ; on the third day the
legs are vifible, on the fourth the wdngs,
foon afterwards the probofcis, and laftly
the animal perfecftly formed. Thefe obfer-
vations wxre firft made by Reaumur, and in
years paft I have amufed myfelf with repeating
them.

But the application of heat made me ac- ,
quainted with another truth. By boiling I
difcovered the point, or the embryo, fom.e
days before it ufually appears. I have not

C c 4 feea

392 DISSERTATION IIlJ

feen it indeed in feeds, containing a liquor in
which the embryo floats, but in fome of thofe
in which the liquor coagulates and is infpif-
fated. Several feeds were taken from the
fame ovarium, and fome of them were boiled
for a few inftants, and the reft left to them-
felves. In the latter I could not difcern the
embryOj but it was plainly to be diftinguiihed
in the former. The difference arifes from the
confolidation of the particle, or the embryo,
by the boiling water ^ in the other feeds it did
not ftrike the fight, on account of its tranfpa-
rency and fluidity.

XXXIX. I come to the objeftion derived
from the infulation of the embryo- in the
feeds; from this circumftance it might be
fuppofed to have no dependance upon them,
and confequently to originate from the liquor
in which it floats. The embryo certainly,
in fome cafes, feemed to fwim at liberty in
the liquor, nor could I difcover any connexion
with the feeds, but on other occafions I ma-
nifeftly difcovered the connedling medium,
as in the common bean, the radifh, and the
Syrian fhrubby mallow; it confifts of a mu-
cilaginous filament, of which one end infi-
nuates itfelf between the lobes, and is in-
ferted into the plantule, and the other end
paflTes out of the lobes, and is attached to the

infid^

DISSERTATION III. 39^

infideof the feed (vi. viii,xix). This fila-
ment probably confifts of a number of veffels,
defigned, like the umbilical cord in animals,
to convey nutriment to the plantule and
lobes, whether the nutriment be the liquor
lying in the cavity of the feeds, filtered and
rendered perfed: in thefe vefl^els, or the fub-
ftance itfelf of the feeds, at the expence of
which the lobes and plantule grow 3 for it
conflantly happens, that as thefe parts are
enlarged, the internal fubftance of the feed
is deftroyed, and at length reduced to a mere
fkin. But befides the manifeft communica-
tion formed by this filament between the em-
bryo and the feeds, I have found, in more
inftances than one, that it communicates at
other parts; as is obvious in broom, peafe,
kidney beans, chick-peafe (iv. vii. ix). If I
have fometimes not been able to find any liga-
ment paffing from the embryo to the feed, it
is not therefore to be concluded, that there
exifts none, but that it cannot be difcerned,
either on account of its minutenefs or tranf-
parency. For as the embryos, in which the
filament is vifible, are unfolded within the
cavity of the feeds, in the fame invariable
manner as is obferved by Nature, in embryos
appearing without this conneding medium,
we have juft reafon to infer, that it exifts in

the

394 DISSERTATION Iin

the latter as much as in the former. That
the minutenefs, and much more the tranfpa-
rency of thefe cords, may hinder them from
being feen; not to mention the proof afforded
by the embryos themfelves before they are
fubjeded to the ad:ion of fire (xxxviii),
is confirmed, by a ilriking in fiance, in the
tadpoles of the fetid toad, while they as yet
float in the liquor of the amnion : thefe tad-
poles are provided with an umbilical cord, but
which is not viflble on account of its tranf-
parency.

As it is evident, therefore, that we have
no foundation for fuppofing the embryo to be
mechanically formed in the ovarium of the
plant, and as it has been moreover proved,
that it does not depend upon the powder of
the male, it remains to be inferred, that it
pre-exifls in the ovarium. In favour of its
pre-exiflence we have another very powerful
argument, in the communication effedled by
the filaments between the embryo and the
feeds; for honce it is clear, that the feed and
the embryo compofe but one organic whole.
As then from all my obfervations it appears,
that the feeds pre-exifl in the ovarium long
before the opening of the flowers, I fee no
reafon why we fhould not alTert the fame
thing of the embryos.

XL. The

DISSERTATION III. 395

XL. The celebrated Muller, a gentleman
of Denmark, made at Geneva, feveral years
ago, under the infpedion of Mr. Bonnet, an
obfervation, nearly approaching to thofe re-
lated in this Diflertation. He found the feeds
of peafe arranged in rows within the pods
before the opening of the flowers, and con-
fequently before the adion of the pollen had
been exerted; but he was not folicitoua to
pufh his obfervation any farther, by examin-
ing the infide of the feeds, or by tracing the
progrefs of evolution. The philofopher of
Geneva could not but deduce important'con-
fequences from this fad;. He began to re-
fled upon the nature of the feeds, that they
were bodies admirably organized, bodies now
in miniature what they were foon to be at
full length ; that, like all ' the parts of the
egg taken together, all the parts of thefe
bodies confpire to form an organic whole.
He juftly concluded, that in the feeds of
peafe, fliewn to him by the Daniili naturahft,
the plantule exifted with its lobes, as in the
egg, however diminutive, the embryo, with
its covers, lies concealed. Hence he
thought himfelf authorized to infer, that as
the feeds of peafe exift before the expanfioii
of the bloffoms, and, of courfe, before the
afperiion of the fecundating dufc, fo the

lobes

39^ DISSERTATION IH.

lobes and plantule pre-exifl in like man-
ner {a)i the very fame confequence which I
have above deduced from my numerous obfer-
vations (xxxix).

I may poflibly be afked by fome curious
perfons, whether, after having abundantly
proved, that the embryos of my plants exift
before fecundation, or, to ufe an expreffion
equally applicable to thofe which require the
fecundating duft, and thofe which do not,
before the opening of the bloffoms, I ever
thought of having recourfe to fome contri-
vance for rendering them vifible before this
period. It is proper to inform fuch enquirers,
that the idea has not only occurred to me,
but that I have put it in pradice, though
indeed without eifed:. I have taken the feeds
out of the clofe and comoad: bloffoms, and
difTecSed them under a powerful magnifier,
but have never been able to difcover any
thing more than by a glafs of inferior power,
that is to fay, an homogeneous gelatinous
matter. I doubt whether the embryo might
riot be withheld from my view, more by its
tranfparency, for the jelly was tranfparent,
than its fmallnefs. I boiled fome feed for a
little while, and fteeped others in fpirit of

(a) Pallngencfie, T, i. page 420, 421.

wine.

DISSERTATION III. gpy

wine. The jelly was infplfiated in both
cafes, but the embryo was not rendered con-
fpicuous. Coloured infufions have fome-
times been employed by naturalifts, with the
utmoft advantage, to bring into view thofe
organs of plants, which are otherwife invi-
fible. By thefe means Mr. Bonnet has dif-
covered the fmall vellels which arife from
the embryo, and pafs in a ferpentine direc-
tion through the fubftance of the lobes {a).
I put feveral feeds into differently coloured
infufions, and they acquired, both externally
and internally, the colour of the infufion.
But the embryos were not rendered in the
fmalleft degree perceptible. Thus unfuccefs-
ful did thefe various trials, as well upon
clofed as expanded bloffoms, prove, with re-
fpecfl: to the embryos, nor were they more
fortunate with refped: to the lobes. The
fame thing happened after the falling of the
flowers, and the formation of the cavity fo
often defcribed. The whole advantage gain-
ed by my applications arofe from fpirit of
wine, which infpiffated the liquor of the ca-
vity and the embryo at the fame time, fo
that it might be difcerned five or fix days
fooner, as I collected from the examination
of other feeds of the fame a^e left on the

o
(a) Recherches fur I'ufage des feuilles.

plant.

398 DISSERTATION HI.

plant. This refult adds confirmation to the
truth above eftabUfhed, that the embryos are
not generated, but only unfolded in the feeds
(xxxviii, xxxix). It moreover proves the
extreme difficulty, I might fay, the impoffi-
bility of obtaining a view of the plantule
before the expanfion of the bloffoms. When
fpirit of wine enabled me to difcern it, it
was yet a moft diminutive atom, notwith-
ilanding fifteen days had elapfed fmce the
opening of the bloffom in which it grew.
Now the plantule had, doubtlefs, in this in-
terval, palTed through feveral fucceffive ftages
of growth. And how prodigiouily rapid is
the growth during this firft period ! How
inconceivably fmall, therefore, muft the
plantule be before the opening of the flowers !
Is it not then unreafonable to hope, that we
ihall be able to difcern an object fo exceffively
diminutive ?

XL I. The illuflrious Haller was the firft
who fhewed, that in birds the fetus exifts
before fecundation. I have extended this
difcovery to different fpecies of amphibious
animals. Thefe fzSis led me to believe it
probable, that the fame pre-exiftence takes
place in all animals. What has been dif-
Govered in various individuals of the animal

kingdom.

DISSERTATION III. 399

kingdom, has been alfo obferved in feveral
forts of plants. I have therefore an equal
ri"^ht to draw the fame conchifion with re-
fped to all plants. But if I may exprefs my
deliberate opinion on this important topic, I
dare not affirm that the embryos, in all cafes,
exiil: before the opening of the bloiToms.
Such a decifion would be precipitate; we
may learn from a thoufand examples the va-
riety of Nature, even in thofe operations
which are defigned to accompliih the fame
end. I therefore only obferve, that till the
contrary fhall be proved, we have juft reafon
to continue in. believing pre-exiilence to be
univerfal. Hence we have a new and ftrik-
ing point of analogy between plants and ani-^-
mals, to be added to the many others long
known; and hence the fufpicion, that thefe
two tribes of organized beings compofe, per-
haps, only one immenfe family, receives
ftrong confirmation.

xLii. Baiil and mercury are two plants,
which unite with many others, to fhew the
neceffity of pollen to fecundation. The
latter of thefe is particularly deferving of
the refiedions of the philofopher. Female
plants of m^ercury, at no great diftance from
the males, remain fterile, becaufe the fecun-
dating atmofphere, if I may fo fpeak, of the

latter.

400 PISSERTATION m.

latter, is not far diffeminated, on account of
the fmall quantity of pollen produced by
them (xxxiii. xxxvi). If the males be
brought near the females, they bear fome
produdive feeds (xxxiv) ; but if the males
be placed almoft in contadl with the females,
the greateft part of the feeds will adhere and
ripen and germinate (xxxv). Should the
males be again removed, the females return
to their former barrennefs (xxxvi). This
experiment is exactly conformable to one re-
lated by Duhamel and Bernard Jufiieu.
Thofe botanifts having obferved, that a fe-
m.ale turpentine- tree, growing in a garden at
Paris, remained conftantly barren for want
of a male, notwithftanding it flowered every
year, determined to bring one near it. The
very year they put their defign in execution,
the female bore a plentiful crop of fruit and
productive feeds. But the following year the
male, which grew in a pot, being carried to
its former ftation {a), the female relapfed
into its accuftomed ilerility (/5).

XLIII*

(a) Duhamel Phyfique des Arb. T. I.

(^) There is growing in the Bifhop of London's garden, at
Fulham, a male tree of this fpecies, and in the botanic garden
at Chelfea, a female. Some years fince an attempt was made
to fecundate the female, from which the feeds always drop
prematurely, by carrying fome branches cut from the male,

and

DISSERTATION III. 40I

XL II I. The fucGefsfijl experiment of Mr,
Gleditfch upon the palm, denominated Cha-
mairops^ by Linnaeus, and by Boerhavc Palma
dadlylifera major ^ fpinofa^ fcemina^ folio jla-
belliformiy has been much celebrated. This
palm, which grew in the Royal Garden at
Berlin, and is perhaps ftill growing there^
had never borne fruit, notwithftanding it was
eighty years old. The fagacious naturalift
fufpecting, that the faihire arofe from the
want of a male plant in the garden, and
having no opportunity of availing himfelf of
the expedient employed by the two Academi-
cians of Paris, had recourfe to the only alter-
native remaining. He procured fome pollen
from the male of the fame fpecies, and
fprinkled it upon fome of the female blof-
foms. The event correfponded admirably
with the views of the curious obferver. All
the flowers that were touched by the pollen

and fixing them upon the female^ But the experiment, from
whatever caufe, proved unfuccefsful : whether the antheras had
already ihed their powder, or whether it was fhaken ofF ia
carrying. Plants of the turpentine- tree are fcarce and valu-
able ; it would therefore be an object, not only of curiofity,
but of ufcj to fucceed in the fecundation of the female ; and
furely the end may be attained* by a little patience and dexte-
rity. Let fome pollen, for inllance, be gathered, and care-
fully fprinkled upon the female bloffoms, according to the me-
thod fuccefsfuUy employed by Mr. Gleditfch, jin impregnating^
the palm. T.

Vol. IL D d produced

402 DISSERTATION IIT.

produced dates in proper feafon, and from
the feeds which were planted there fprang an
equal number of young palms ; but the
other flowers, upon which the influence ot
the pollen had not been exerted, lofl: the
greateil part of their fruit, while it was yet
fmall, and in the little that remaained, there
w^as no ftone, nor did the feeds germinate (^2:).
One circumftance attending this artificial fe-
cundation deferves to be mentioned. The
pollen employed by the botaniil: of Berlin
was not frefh, but dry ; it had been gathered
nine days.

When I was making my experiments upon
mercuryv it did not occur to me to attempt
artificial fecundation; but 1 have not the
leafl: hefitation in fuppofing, that my fuccefs
would have been the fame as that of the Pruf-
fian naturalift. And as fuch experiments,
under the guidance of a phiiofophical mind,
cannot but throw great light upon the obfcure
fubjed: of the fecundation of plants, I ex-
hort botanifts to undertake them upon mer-
cury, a plant, not confined, like the palm,
to a few countries, but widely fpread over the-
globe. ' I could wifh, that, in the firft place,
if I may be allowed to exprefs my flender

(a) Acad, de PrulT. for the year 1767.

'}?.■ . " . '

S'iM' conceptions.

DISSERTATION III, 4O3

Conceptions, the pollen of the mercury might
be carefully examined, in order to difcover
what part of it is the immediate caufe of fe-
cundation. I have already obferved (xv),
that it confifls of veficles. In thefe veficles
the induftry of enquirers has detected a fub-
tile liquor, containing a multitude of glo-
bules. This fimple obfervation has given
rile to feveral difcordant opinions. Some
have fuppofed the globules to be the imme-
diate agents of fecundation; others have at-
tributed this effedl to the fubtile liquor; nor
have there been wanting: others, who have
imagined it to be produced by a fluid of ex-
ceffive tenuity, a fpecies of vital fpirit, ex-
haling from the above-mentioned liquor,
which ferves only as a vehicle to the fluid [a),
A few delicate experiments vv^ould perhaps de-
termine v/hich of thefe opinions is the true
one. With refpedl to the lafl:, v/e might
probably put it to the proof, by occafloning
the exploflon of the veflcles by moifture, and
expofing the liquor they yield for fome time
to the air. If it will not now fecundate the
female bloflbms of mercury, it would feem,
that it is effected by fuch a fpirit, or at leafl:
the moft fubtle, active, and volatile part of
the liquor, which by this time has evaporated.

{a) Adanfon families des Planter, T. i.

D d 2 But

404 DISSERTATION III.

But fhould fecundation neverthelefs take
place, infteadof imputing it to the fpirit, it
mufl be afcribed either to the hquor pr the
globules, and then the refult of my experi-
ments upon animals would be verified with
refpecl to plants : it would appear, that the
efficient caufe of fecundation is not the fubtle,
volatile part of the fpermatic liquor, but the
grofs fenfible portion. Next, in order to
learn whether the globules, or the liquor
independent of them, produces fecundation,
it will be neceffary to feparate the one from
the other, and touch different female blof-
foms with each ; nor do I think, that a
perfon accuflomed to delicate experiments,
would find it very difficult to eifeft this fepa-
ration.

XL IV. Mr. Adanfon lays it down as a cer-
tain truth, that the fmalleft particle imagin-
able of pollen falling upon the ftigma, will
produce fecundation (a) . If this were really
the cafe, the impregnation of plants would
in this particular agree with that of feveral
ramphibious animals, for which I have ihewn
an infinitely fmall drop of feed to be fufficient.
But this celebrated Academician mufl allow
me to remark, that what he advances is a
mere bypothefis, in fupport of which he

(a) L, C.

does

DISSERTATION III." 405

does not bring the fmalleft prefumptioii,
much lels any proof: nor does he offer cither
prefumption or proof of the exiflence of this
vital fecundating fpirit in plants, notwith-
ftanding he afferts, that the embryos of ani-
mals are impregnated by a fpirit of the fame
nature, iffuing from the feed; an •affertion
which my experiments fliew to be abfolutely
falfe. Nothing, however, can be eafier than
to bring this hypothelis to the tefl of proper
experiments, by artificially fecundating mer-
cury. And were fuch experiments diverfiied,
like mine upon animals, I have no doubt but
that they would furnilL new and curious in-
formation.

XLv. The feminal liquors of animals and
plants poffefs one property in common ; they
retain their virtue for fome time after they
have been taken from their natural refervcirs.
The feed of frogs and toads preferves its
prolific power for feveral days after it has
been taken out of the animals; and the fame
quality was obferved in the pollen of the
palm, feveral days after it was feparatcd from
the plant (xliii). But the feed of animals
becomes in no very long time inert. Are wc
to fuppofe that the fame thing happens to
the pollen after the dropping of the ftaniina ?
If we confider the phyfical caufe v/hich, ac-

D d 3 cording

406 DISSERTATION IH.

cording to every appearance, deftroys the
virtue of the feed of aninaals, it vi^ould feem
as if the inference was not very juiL The
feed of animals becomes unfit for fecunda-
tion exa<ftlyln proportion as it putrefies ; and
if it can be preferved from putrefaction, it
continues to be prohfic. This fpecies of
corruption does not feem fo much to be ap-
prehended in the pollen, or rather in the at-
tenuated liquor which it contains. From the
analyiis given by able naturalifts we learn,
that the liquor is of an oily nature, and re-
fufes to mix with water [c). It appears,
therefore, not unreafonable to fuppofe, that,
like other vegetable oils, it will keep for a
long time 5 hence fome may be induced to
think that the prolific virtue of the pollen
continues fo much longer than is generally
believed, that there is nothing extravagant in
imagining it to laft for many mionths, nay for
a number of- years. But notwithftanding its
oily nature, which may feem likely to pre-
fer ve it from putrefying, the following
reafons lead me to fuppofe that it foon lofes
its prolific power. In order that this liquor
may produce its proper effecl, and the fame
obfervation is applicable to the globules and
the fpirit of Adanfon (xliii), it muft at the

{c) Gleditfch. 1. c'

time

DISSERTATION III, 407

time it ads on the ftigma ifiue from the ve-
licles, or have been lately diicharged, for it
is natural to fappofe, that by expofure to
the injuries of the air it muft be difperfed,
altered, and rendered unfit for fecundation.
But this difperfion and alteration muft una-
voidably happen to pollen, that has been
ripe for fome time. According to Mr. Need-
ham's obfervation, which has been verified
as well by others as by me, that if the ripe
pollen of any plant whatever be examined by
the microfcope, we ihall always perceive
fome veficles from which the liquor has
efcaped ; thofe that ftill retain it will explode
if they be wetted, hke an eolipile fuddenly
expofed to a ftrong heat. It is equally agree-
able and furprifing to fee the fuccefiive explo-
fion of the veficles, and the projection of the
liquor, a few inftants after the application of
water. From this experiment it appears,
that the veficles remaining after fecundation,
whether they float in the atmofphere or 'fall
to the ground, cannot continue long vnthout
exploding and difpelling their contents, be-
caufe fome veficles will burft fpontaneouily,
and the explofion of the reft will inevitably
be occafioned by vapour, dew, or at leaft by
rain. Thefe agents will, I am perfjaded,
prevent the pollen from retaining its prolific

D d 4. virtue

408 DISSERTATION III.

virtue long after the feafbn of fecundatloriv
That rain, in particular, is deftrudive of this
quality evidently appears from thofe plant s>
which, during the time of flowering, are
expofed to violent rains, being either barren or
bearing only unprodu<flive feeds. This failure
is owing to the explolion of the veficles before
they reach the ftigma, the fituation in which
they fecundate the embryos contained in the
ovarium.

However this may be, to return for a mo^
ment to the continuance of the virtue of the
pollen, after the ftamina are withered. — -The
term ought certainly to be afcertained both in
mercury and other plants. The fubjecl is
highly interefting,

XL VI. It has been ufually admitted as a
decided point, that fecundation is effected by
fome veficles, or, according to the common
expreffion, by fome granules of pollen, which
entering through the fligma into the ftyle,
advance into its longitudinal dud, till being
ilopped by the narrownefs of the paffage, and
jnoreover moiftened by the juice oozing out
from the fides, they burfi: and fend forth the
fpermatic vapour, which penetrates as far as
the ovarium, and impregnates the feeds con-
tained in it. But this explanation has not
Jigd the good fortune of meeting with Mr.

Adanfon's

DISSERTATION III. 4O9

Adanfoii's approbation; not that he denies
the pre-exiftence of the feed in the ovarium,
nor that it is fecundated by the liquor of the
pollen, or, as he calls it, by the vital fpirit
refiding in it. But he pretends that the vital
fpirit does not pafs along this dud to the
feeds, becaufe in many plants there is no fuch
du6l exifting. He allows, indeed, that in
fome plants, as in feveral of the liliaceous
tribe, the canal extends from the ftigma to
the ovarium, but he aflerts that it is other-
wife in the greater number of other plants,
which have their piftils imperforated. In
order, therefore, to explain the manner of
fecundation, he imagines that his vital fpirit,
which in fubtility and adivity is equal to the
eledrical fluid, pafles along the tracheae that
terminate at the furface of the ftigmata into
placenta, whence it iniinuates itfelf into the
feed, and fecundates the embryo (a). The
illuftrious Bonnet, in a fenfible and profound
Memoir, entituled, Idees fur la Fecundation
des Plajttes (^), mentions the opinion of
Adanfon, but appears little fatisfied with his
hypotheiis concerning the trachece, on ac-
count of its being altogether precarious, al-

{a) L. C.

{b) Inferted in Rczier's Journal for 1774* and reprinted in
\i\i works.

though.

4IO DISSERTATION III.

though it is propcfed by the author as a well-
afcertained fact, and moreover finds great
diiiiculty in admitting that any piilils are
without a ducfr, and perfectly clofed. Hence,
prompted by his conftant ardour for the in-
veftiga'tion of truth, he takes occafion to
exhort philofophical botanifls to exam.ine this
matter afrefii. Although it was not my pur-
pofe, when I was making enquiries concern-
ing the generation of plants, to enter upon a
complete tx^mimtion of the internal ftruc-
ture of the piftil, I did, hov/eyer, occafionally
examine fome. For this purpofe I cut the
piilii tranfverfely into feveral pieces, and then
placed them vertically under the microfcope.
Thus I could afcertain whether they were
perforated or not. I found that fome piflils
were completely perforated from the fligma
to the ovarium; in others, the canal did not
reach above half the length, and fome times
not fo f:ir down. Laflly, in feveral other
piftils there appeared no perforation at all.
Upon the piitils of mercury I made no ob-
fervation, v/hicb, however, it would be
proper to do; and then the validity of that
hypothefis, according to which fecundation
is not effeded by the paffage of a fubtile im-
pregnating fJabftance along the duel of the
piilii, but along the tracheae, which termi-
nate

DISSERTATION III, 41I

nate on the furface of the ftigmata, may be
ibrutinized. I could wifh that fome pollen
might be laid upon their furface, while care
is, at the fame time taken, that none enters
into the aperture of the dud:: and that on
other piftils the inverfe experiment might be
attempted, that is to fay^ that fome pollen
might be introduced into the opening-, while
the furface remains untouched, and that we
might fufpend our opinion till we know the
ill Lie of the trial.

XL VI I. But although I could difcern no
du6l in the piftils of fome plants, I am not,
with Mr, Adanfon, difpofed to think that
there are nOne. V/hile I fincefeiy wiih for
knowledge extenfive as his, I fliouid be forry
to reafon in the fame m^anner. I have found
that the veficles or granules of pollen vary
with the fize of the plant, an obfervation
which has been made and publifhed many
years fince by other naturalirLS. Some are fo
large as to be perceptible by means of a fingle
glafs; while others are fcarce difcerned by
the aid of the microfcope. Hence I can be-
lieve, without reludlance, that there are fome
which no afliftance can bring under the
cognizance of the fenfes. If we fuppofe the
duel in the piftil to be the canal of fecunda-
tion, its area will be proportional to the bulk

of

412 PISSERTATION II!.

of the granules which are to enter it: if they
be large, the paffage muft be wide ; if they
be very fmall or inviiible, the paffage will
probably be fo alfo. According to this fup-
pofition then, we fhall not be able to fee the
duLl:, Ihould it even exifi. In order to de-
terniine whether my refledion be juft, it will
be only neceiBiry to obferve, whether the
granules of pollen are inviiible when the piftil
appears to be without a duc^. But Ihould
the granules be perceptible, and the piftib
have no canal, as far as the eye can judge, it
would hence follow, that this is really the
cafe, for it may eaiily happen, that the piflil
fhall be examined at a time w^hen the dud: is
either not yet open or has clofed. Let me at
once illuftrate and prove this propofition. In
the Sponfalia Plantaruraj which is without
doubt one of the beft differtations in, the
Amcsnit cites Academicce^ the celebrated Lin-
naeus defer ibing the amours of plants with
great complacency, and in the fame flrain in
which another naturalift would defcribe the
amours of animals. He adduces^ among
other evident marks of the female's appetite
for the male, the diredion of the iligma to-
wards the piftil and its dilation, like the gap-
ing of a ravenous dragon, longing for the
pollen of the male, with which, when it is

fatiatcd.

DISSERTATION III. 4I3

fatiated, it clofes. Gr at tola, thefe are his
exprelRoiis, (eflro venerea agitata pijiillum ftig^
mate hiat rapacis injiar draccnis nil niji mafcu"
linum puhcrem affeBans-, at fat i at a ritlum
claudit. He applies terms of like import to
various other plants. The reader muft by
this time perceive, that what I would obferve
is, that we may poflibly m.ifs the exa6t feafon
of the female's ardour for the male ; and
then the aperture of the ftigma will either be
clofed after fatiety, or not yet opened.
Hence we fliould falfely conclude, that thefe
ftigmas are without duds. A circumftance
of the fame kind happens to various animals,
particularly to fome of the am.phibious clafs,
as frogs, toads, newts, of which the females
have their ovidu'fls quite free and open at the
feafon of their amours ; but at all other times
they are fo narrow, that air can fcarce be in-
troduced into them by means of a fmali fy-
ringe. If I fhould be alked, w^hen the fe-
male is mofc ardent, and when, of courfe,
the duels are to be fought for, I would anfwer
with Mr. Gleditfch, that at this period the
delicate papillce upon the ftigma are flightly
covered with moifture of the fime kind as
that which tranfudes from the veficles of pol-
len, for then, according to that author, fe-
cundation takes place.

XLVIII.

414 PISSERTATION HI,'

XL VII I. I have before obferved, that the
furface only of the ftigma without the orifice
might be touched with the pollen of mercury
(xLvi). But I fhould wifh to know alfo,
what would be the confequence of touching
other parts, as for inftance the furface of the
ftile. Fecundation might be alfo attempted
upon the leaves and root of female mercury.
This idea is not my ov/n, but partly at leaft
Mr. Bonnet^s, who obligingly communicated
it to me fome time fince, that I might put it
to trial, but I have been hindered by my other
purfuits. Let us hear him in his own
words: *^ The author," (v/ho is, as he fup-
pofes, M. Fougeroux, fee the long note at
paragraph xxv), ^* finiihes his Memoir with
fome ingenious views, which to him appear
worthy to be followed up : I earneilly wiih
you could undertake this talk : He would be
glad, for inftance, that attempts v/ere made
to fecundate female plants by the root.
This idea certainly deferves to be brought to
the teftof experiment. But the root is at a
great diftance from the flower, and the impreg-
nating fpirit DTiuft travel far before it can
reach the ovarium. It would be therefore
proper to try the fhorter road of the leaves,
and above all of the petals/'

XL IX.

DISSERTATION III. ^t ^

XL IX. But it is time to proceed from mer-
cury to other plants, not lefs worthy of the
attention of the naturahfl. In mercury, as
well as in bafil, we have teen the neceffity of
pollen to fecundation. The pumpion or
gourd with ihield-form fruit, the citron
pumpion, hemp, fpinach, exhibited a phe-
nomenon diredtly contrary : they produced,
without the influence of the male duft, feeds
capable of perpetuating the fpecies. And in
order to be fatisiied that the dufi: had no fliare
in producing the efFed:, recourfe v/as had to
the moft vigilant precautions, and the molt
decifive proofs. The pumpion v/ith Ihield-
form fruit flowered in a place many miles
diftant from any plant of the fame or a neigh-
bouring fpecies : moreover, the male flowers
were all plucked off at their firft appearance
(xx, XXI ). The fame precautions were
ufcd with reipe6t to the other fpecies of
pumpion^, with the addition of a third; the
accefs of the external air to the female
flowers, was prevented during all the time,
in the ccurfe of w^hich they muft, in the
opinion of botanifts, be impregnated by the
pollen > for this purpofe the blofibms and
branches v/ere introduced into giafs bottles
perfedly clofe (xxxii). Various precautions
were likewife taken with hemn. In the flrft

place.

4t5 dissertation in,

place, feveral female individuals were fhut
up in an appartment> from three weeks be^
fore their flowering to the time of the ripen--
ingof the feeds. Secondly, fome branches
were inclofed in bottles for the fame fpace,
as in the citron-pumpion. Thirdly, fome
female ftalks were made to flower fix weeks
before thofe which grew in the hemp-yards.*
Lafl:ly, I aflured myfelf, that no male blof-
fom ever grew upon the females (xxvi,
XXVII, XXVIII, xxix). Precautions of the
fame kind were obferved with refped: to
fpinach ^ fome femiale plants were raifed in a
garden, in which there were no males; fe-
condly the pot was completely covered with a
glafs receiver, when the flowers with piftils
were in bloifom ; thirdly, bloflx)ms with
piftils were procured earlier than the ufual
appearance of bloflbms w^ith ftamina in the
gardens and fields: laflly, I took care to
fatisfy myfelf, that none of the females ever
produced any male flower (xxx, xxxi, xxxii).
One circumftance relative to hemp I mufl
not omit to repeat ; the feeds of individuals
confined in an apartment, were lefs numerous
and fmaller than of thofe which grow in the
open air. Both thefe defects were fl:ill more
remarkable on thofe branches which were
introduced into bottles (xxvii, xxviii).

Are

DISSERTATION III. 4X7

Are we to fuppofe, that thele defedls arofe
from want of pollen? I am little inclined to
admit fuch a fuppofition ; it is far more pro-
bable, that they were owing to confinement
in an apartment, and what was ftill more
unfavourable, in bottles : hence the plants,
and confequently the feeds could not attain
the fame degree of perfection as thofe, which
in the fields enjoyed the benefit of frefh and
open air, and were fubjedl to the dired: in-
fluence of the folar rays. My opinion is
ftrongly confirmed by thofe plants which
flowered fix weeks earlier than the others,
and, notwithflanding the abfence of the pol-
len, produced perfect feeds as large, and in
as great abundance as thofe of the hemp-
yards, becaufe they were conllantly expofed
to the kindly influence of the air and fun
(xxix). From thefe obfervations on hemp,
pumpions, fpinach, compared with others
made on bafil, mercury, pilm, turpentine,
&;c. &c. it may in general be inferred, that
if a great number of plants require the
powder of the male, in order to fructify,' in
many others fructification has no dependence
on this powder. And although we are as yet
acquainted with a few only belonging to the
latter clafs, it will doubtlefs increafe in pro-
portion to the number, application, and fa-
VoL. 11. E e gacity

4t3 DISSERTATION III.'

gacity of thofe who ihall employ themfelve^
in cultivating this branch of the Natural
Hiilory of vegetables.

L. But by affirming, that there are plants
which bear produdtive feeds independently
of pollen, I am aware, that I (hall incur the
difpleafure of all modern naturalifts and bo-
tanifls. They will exclaim againft me with
the utmoft indignation, and reproach me
with having advanced the moft abfurd of all
poflible propofitions. I fhall be told, that
from the days of Caefalpinus to the prefent
hour, every naturalift of diftinclion. Grew,
Ray, Camerarius, Morland, Geoifroy, Vail-
lant, the Juffieus, Duhamel, Adanfon, Bon-
net, &c. 8ct. have admitted the two fexes of
plants, and the neceffity of both to fecunda-
tion— that the prince of m.odern botanifts
has confecrated an entire eiTay to the celebra-
tion of the amours of plants, and to the de-
fcription of their fexual parts — -that upon
this difliincrion of fex, as upon a folid and
im.moveable bafis, he has founded the great
edifice of his famous Sy/iem of Nature — that
in conformity with this theory he defines the
blolToms, the or gam of generation in plants^
iddich are fubfervient to the impregnation of the
feeds — that in the effay, to which I have re-
ferred, he ihews, that the duil of the fta-

mina

tJlSSERTATION III. 4!^

mina is not diffiifed, till the ftigma of the
piftil is in a fit condition to receive its in-
fluence— that the piftils are always difpofed,
with refped; to the ftamina, in a fituation fa-
vourable for the reception of the pollen.
They will bring to my recoil edlion the proof
of the neceffity of the piftils and ftamina to
fecundation, deduced from experiment ; for
if the ftamina or piftils of hermaphrodite
flowers be cut away before the time of blow-
ing, fructification will infallibly be prevented ;
and the fame failure is obferved whenever
the ftamina are converted in petals, or the
piftils are expanded into little leaves. Finally,
they will adduce, in full confirmation of
thefe aflertions, the various inftances of arti-
ficial impregnation, fuccefsfully attempted
by different naturalifts upon various fpecies
of plants, by means of pollen. From all
thefe confiderations, it would feem no
longer to be queftioned, that the fecunda-
tion of plants, in confequence of the a(flion
of pollen, is one of the moft univeriai laws
of Nature.

LI. Such are the objedtions which I feem
to hear urged againft me by the learned and
worthy maintainers of fexualifm. I m.uft-,
however, inform them, that I was not un-
acquainted with thefe arguments, when I

E e 2 made.

420 DISSERTATION III.

made my experiments upon plants. I knew,
moreover, that fome of them were diredly
oppofite to experiments related by the northern
Pliny; as that, for inftance, defcribed by
him in the following terms. *' Cannabem
llores mafculos tantum ferentem, li ante di-
vellit ruilica quam cannabis feminifera fiores
piflilliferos non aperuerit, nullam aut fane
exiguam portabit feminum copiam [a), I
alfo had in view an affertion, nearly alike, of
the iiluftrious Duhamel, in his Phyfiqiie des
Arhres. It has been cbferved^ fays he, that
an infulated pla?it of fpinach produces but a
'very little feed capable of germinating. When
I firft read this writer, 1 gave full credit to
his affertion, for I had no reafon to doubt of
it; and even quoted it in a note on the Con-
iernplation de la Nature^ tranflated by me, and
publiihed at Modena, in the year 1770.

Thefe refpectable authorities ferved only to
render me more diligent, cautious, and affi-
duous in my experiments. They had not
fuch influence as to make me adopt an opinion,
contrary to that to which fads pointed : nor
fhall they now hinder me from making, with
proper deference, fuch fl:rid:ures upon the
inftances juft . quoted, as are fuggefled by
the difpaffionate love of truth. To begin

(«) Spons Plant.

with

DISSERTATION III. 42 1

with the fad: mentioned by Linnaeus, it does
not appear that he made any experiment upon
hemp ; he feems merely to have adopted the
vulgar notioKi, according to which, if the
male hemp be pulled before the flowering of
the female, the latter will produce either no
feeds at all, or only very few. To fl:iew the
falfenefs of this notion, 1 have only to advert
to my experiments, in which every ftalk of
hemp proved fruitful, though they were all
kept fo clofe, as to be perfedly exempt from
the influence of pollen — not to mention the
common pradice, in the territories of Reggio
and Modena, of pulling the male plants at a
period, after which the females grow vigour-
oufly for feveral weeks, and bear productive
feeds. I intreat the learned reader to call to
mind the twenty-fourth paragraph, in which
this pradice is defcribed; and alfo to com-
pare the force of my obfervations on hemp,
with the few contrary exprefiions of the late
Upfal Profeflx)r, and- then to decide. I give
the fame anfwer to Duhamel's intimation
concerning fpinach. If that illufl:rious na-
turalifl: had deduced the barrennefs of this
plant when infulated, from experiment of his
own, I would have difcuffed them, and have
rendered them all the juftice they would have
deferved; but he barely mentions the com-

E e 3 moA

422 PISSERTATION III,

iBon fuppoiition, which is contradided by
the facts adduced by me. ^

Vi^ith refped: to the diffufion of the pollen,
which was the firft of the three- arguments in
favour of the fexual fyftem, only at a time
when the ftigma is in a fit condition to re-
ceive it; and with refped: to the favourable
polition of the ftamina and piftil, the philo-
fopher will immediately perceive, that thefe
are by no means dired: proofs of the fexual
fyftem, but mere confiderations relative to
convenience, calculated^ if I may employ the
expreffions of the great Verulam, rather to
allure, than to extort aflent.

Lii. Of the fecond argument, deduced
from the failure of frudification, when the
ftamina or piftils are either cut away or dege-
nerate, I muft take the liberty to obferve, that
fuch inftances do not prove that thefe parts
are the organs of generation, but merely that
they have fome concern in this fundion, as
w^ell as m.any other parts, which yet have
never been fufpeded to be appropriated to
generation. The only fads which clearly
evince the diftindion of fexes in plants, are
inftances of the failure of frudification in
females placed at a diftance from males, and
of artificial fecundation, which was the third
argument adduced. But ihall we conclude,

with

DISSERTATION IIT. 423

with thcfe worthy naturaUfls, that fuch fads,

of which fo few- are known, in comparifon

with the imnienfe multitude of plants, are

Sufficient to eftabliili an univerial diftindion

of fexes ? Is it not, on the contrary, evident,

that they have deduced a general conclufion

from particular premifes ? They ought at moft

to have faid no more than that, confidering

the clofe analogy which plants of different

clafTes, genera, and fpecies, bear to one

another in their properties, and that as a dif-

tinction of fcxcs has been demonftrated in

fome individuals, it probably extends to

others. Thus, from my difcovery of the

fetus's pre-exiftence in the female of different

amphibious animals, and from a like obfer-

vation made on birds by the great phyfiologifl

of Berne, I fuppofed that I might juiily

infer, that the fame pre-exiflence extends to

other animals. After I had found, that the

embryos of feveral plants exift before the ap-^

pearance of the flowers (xlx), I made the

fame inference with refped to all. others.

But the favourers of the fexual fyllem are not

warranted, by fo inconfiderable a number of

fads, to cflablifh it as an univerfal law, as

others have done, befides Linnaeus, who,

without limiitation, defines flowers, the organs

of generation of plajits^ which are Juhfervient

E e 4 td

424 DISSERTATION Iir^

to the fecundation of the feeds ^ Hence he at-
tributes to plants as many males, or huf-
bands, as there are ftamina. But before he
fo decifively determined the number of huf-
bands, he ought to have been fure that they
perform the office. If this far-famed natu-
ralift had facrificed lefs to nomenclature, and
more to the fpirit of inveftigation, he would
have been led to ftudy the parts of flowers
more philofophicaliy and more profoundly ;
hence he would have been better enabled to
afcer tain the truth or falfehood of his fyftem :
but he was in too great haile to ered: his
own fyftem upon the ruin of Tpurnefort's
and his eagernefs has not, perhaps, been
highly advantageous to the philofophy of
botany.

LIU. Among various particulars concern-
ing the generation of plants, which I com-
municated to Mr. Bonnet, in a letter dated
Odober the i8th, i777> and alluded to in a
note, at paragraph xxv, I mentioned fome
experiments, which were then indeed im-
perfedl, but feemed to fhew, that in fome
plants the fecundity of the feeds was totally
independent of the powder of the ftamina.
Hence I concluded, that botanifts in general
had been guilty of a fpecies of fophifm,
- Although what I then wrote to my illuftrious

friend

DISSERTATION III^ 425

friend was but a fketch of thofe experiments
which I afterwards undertook, yet he ac-
cepted it with complacency, and admitted
my conclufion, notwithflanding his opinion
was before different. In his anfwer, dated
November the 29th, the fame year, he fet
forth the reafons why he had adopted the
fexual fyftem, and fubjoined the following
acknowledgment, which amounts to a pane-
gyric on his candour. ** I am, however,
fufficiently convinced by your experiments,
that all the great naturalifts whom 1 have
enumerated, as well as myfelf, were deceived.
We had all formed a hafty decifion, and
drawn a general conclufion from particular
premifes. We had deduced the neceflity
of the pollen in fecundation, from experi-
ments executed on different fpecies of
plants ; whereas we ought only to have faid,
that it feems to follow, from thefe experi-
ments, that in fuch fpecies the influence of
the pollen appears to be neceffary to fecun-
dation.''

Liv. Such indeed is the fatal rock on
which the genius of fyftem-makers ufually
fplits. — They illogically deduce general pro-
politions from particular proofs. Finding
that certain parts are common to a number
of plants, and that in them they perform

particular

42^ DISSERTATION

III.

particular fuiKflions, and have particular pro-
perties, they determine, with wonderful fa-
cility, that the fame things take place in all
other plants : and on thefe plants performing
fuch funffions, and endowed with fuch pro-
perties, they found their fyflem of botany,
without perceiving, that before the fyftem
can have fuch an unlimited generality as they
pretend, they ought to be acquainted with
all the plants of the earth. But how many
are yet unknown? How many more than are
known ? With what propriety then can the
whole vegetable kingdom be comprehended
under one law ? Does the organic world
afford a fmgle lav/, which can be called uni-
verfal? Have not the laws, which haftily
and imprudently were eftabliilied as uni-
verfal, been found not to be really fuch ? The
learned botanift, Necker, in his Phyjiology of
Moffes {d)y ably points out this defeCl: of
fyftem-makers, in which he diftinguifhes
them from obfervers ; not indeed v/ith great
purity of ftyle, yet vv^ith the utmoft juftnefs
of fentiment. '^ Alterum fyilematicum, al-
terum obfervatorem diftinguimus. Ille non
nifi quibufdam plantarum fpeciebus univerfa
ftabilit fyftemata : a particulari ad univerfale

(fi) PhyHologia MuTcorum, Manhemii, i774'

Concludit,

DISSERTATION III. ^27

concludit, i. e. omnibfis globi terraquci ve-
getabilibus eafdeni proprietates ac iis qiuT ex-
perimentis explorata llint, tribuit. Obfer-
vator omnia theoretica rejicit fyitemata, foils
oblervationibus necnon experimentis innixus,
Naturam pcrfcrutans : perfedtio botanices ab
indlviduorum fingulorum inter (c affinium
eorumque identicorum charaderum notitia
effentialiter pendet. Ea proportione notitia
haec acqiuretufj qua obfervatorum Humerus,
qui valde exiguus, augebitur fyllematico-
rumque cumulus minuetun Certum indu-
bitatumquequod fyftematicum ingenium prs-
cipua caufa fit cur de modico prefeclu bota-
nices dolemus. Syflemata botanica cum tem-
pore exolefcunt, quia Natura ac experien'ia
potiilimum non nituntur."

Lv. That Nature fhould follow a different
procefs in different plants — that fome lliould
require the influence of pollen in order to
multiply the fpecies, while it is not neceffary
to ot'hers, is perfectly conformable to what
we every day obferve in animals to which
they are fo analogous. Numberlefs animals
are incapable of multiplying, without the
concurrence of both fexes, or, at leaf!:, with-
out the intervention of that liquor, upon
which depends the perpetuity of the fpecies ;
^s -is evident in m^an, quadrupeds, birds,

filhes.

428 !>. ISSERTATION III.

fiihes, reptiles, and •infeds. But a vafi
number, on the contrary, propagate without
fuch. means ; as for inftance, the polypes;
under which denomination is included an im-
menfe variety of fmall animals, inhabiting
the bottom both of the freih water, of
ditches, ponds, puddles, and of the fait
water of the fea. To thefe may be added,
the lice of plants, a moil compreheniive clafs ;
\vhole armies dwelling on a iingle individual.
The animalcules of infufions, moreover,
agree with the lice of plants and polypes, in
the mode of propagating the fpecies. I have
ihewn, in my fir ft ejfay^ relative to the nd"
tural hi/lory of vegetables and animals^ that
many fpecies are multiplied by a natural di-
vifion of the body, fome fplitting into two
portions, fome into four, fome into fix, and
others into eight, &c.---that fome are ovi-
parous, others viviparous, and that all are
ftridly hermaphrodites, each individual pro-
pagating its kind, without needing the con-
currence of another. Thus it may, and
really does come to pafs in fome plants, which
multiply without the influence of the fecun-
dating duft.

Lvi. One objection, however, may be
ftarted, and it would be inconfiftent with my

impartiality

DISSERTATION III. 429

impartiality to fuppreis it. It may be urgcd^
by the advocates of the fexual fyftcm, that
although at the time I was making my expe-
riments upon the pumpion with ihield-form
fruit, the citron pumpion, fpinach, and
hemp, I was perfedlly certain that the pollen
had no accefs, yet it might previouily have
impregnated the feeds. It may be faid, that
the female individuals might have been fe-
cundated feveral years before, and that by
this fingle adl, not only the feeds of the cur-
rent year, but thofe of feveral fucceffive ge-
nerations, might have been fecundated.

This obje(fi:ion is only a repetition of v/hat
was modeftly fuggefted by the illuftrious
Trembley, to Mr. Bonnet, v/hen he made
his celebrated difcovery of the hermaphro-
ditifm of the lice of plants. Who kno'ws^
Xaid that naturaliil, fo cautious and deliberate
in his deciiions, but that cm copulation may
fervefor many generations {a) ? Although my
excellent colleag-ue acknowledg-es the quefticn
to be altogether gratuitous, yet, as it was
put by a Trembley, he was anxious to repeat
his obfervations 3 and he juftly concludes,
that the fufpicion is entirely removed by the
produ6lion of ten fucceffive generations with-

(«) Bonnet Corps Organ, p.. 311. Ed. in 410.

out

430 DISSERTATION III.

out copulation (^). With refpedt to my
plants, I muft frankly acknowledge, that I
did not obtain from any of them more than
three generations without the intervention of
pollen. Nor did the nature of the thing
allow me to fatisfy my curiofity fo foon as
P^lr. Bonnet, for he, in the ihort fpace of
three months, .obferved ten fucceflive gene-
rations 'y whereas not lefs than ten years mufl
have paffed, before I could have obtained an
equal number in the fubjects of my experi-
ments. I have not, therefore, been able to
derive fufficient information from this fource ;
yet I can adduce confiderations weighty
enough to overturn the objed:ion. In the
firfl place, all Nature does not afford a iingle
in fiance, wherein one act of fecundation
ferves for feveral generations. The only
cafe, concerning which any fuch fufpiciork
hasarifen, has been abundantly cleared from
it. Secondly, we have inilances of many
fucceflive generations, without copulation or
fecundation, as in the polype with arms,

{b) Notwidiilanding Mr. Bonnet has difcovered and pub-
llihed this fad (o many years ago, and notwithlhnding it has
met with no oppofition from any obferver, Linnaeus advances,
in K\% Syfiema Nature y and in the lafl edition of 1767 re-
peats, this fcandalous propofition. '' A copula parentum
ftscundas nafci filias, neptes^ proneptes, abneptes alfeverant
eutomologi.'*

From

DISSERTATION III. 4^1

From the body of this fpecies fprout fmall
polypes, which, during their evolution, pro-
duce other fmaller polypes, and thefe again
others Hill fmaller and fo on : hence we have
at laft a fcries of generations, growing one
out of another, and all fupported by the
mother polype, of which we are certain,
that ihe has never had any fort of commerce
with her fellows ; becaufe llie was torn, while
yet very fmall, from the body of another,
and ever afterwards kept in the moft perfed:
foiitude (^z). Since, therefore, we obferve
fo many fucceffions in animals, indepen-
dently of the affion of any feminal principle,
why may not, or rather why m.uft not, the
fame thing take place in fome kinds of plants ?
We have no fad: w^hich proves a number of
fucceiiive generations in any organized body,
to be the effect or the refult of an antecedent
ad of fecundation.

Lvii. Although the many fads which I
have related, compel me to rejed the adion
of the powder of the males in feveral plants,
yet I dare not altogether deny the poflibility
of fecundation. What I mean to infinuate
is, that in the courfe of my frequent medi-
tations upon this important fubjed, a doubt

(^J Trembley, Polypca d'^au douce.

has

43^ DISSERTATION IIlJ

has arifen in my mind> whether the feeds In
the ovarium may not be fecundated by fome
feminal principle refiding in the piftil. I
have frequently feen upon the ftigma of cer-
tain plants, a kind of powder exceedingly
like that of the ftamina, though I had at the
fame time clear proofs, that the latter had
not yet burfh from the antherae. But i did
not, I muft own, make any careful obferva-
tions on this fubjecl. My furmife was how-
ever ftrengthened by reading in Kolreuter,
not without furprize, that the properties of
the feminal powder belonging to the ftamina,
are exaCtlv the fame as tbofe of the matter
furniihed by the piftil. Now I have fome-
times doubted, v/hether the duft of the ftig-
ma may not produce the fame effeds on fome
plants, as that of the ftamina on others.
But this is a mere fufpicion, which it would
give me great pleafure to fee confirmed or
deftroyed by fome able obferver. And as I
am fpeaking of the ftigma, let me add, that
I wifh this organ were more carefully exa-
mined, than it has ever yet been; great at-
tention ftiould be paid, in order to determine
whether it is imperforated or not in fome
plants (xLvi, xLvii). Such refearches,
united with others relative to the ftamina,
would contribute to diffipate the mift which

covers"

DISSERTATION 111. 433

covers the fecundation of plants. As I have
derived great advantage in my attempts to
illuftrate this fundion in animals, from arti-
ficial fecundation. I cannot but ao;ain re-
commend the fame means; nor do I doubt,
but that they will throw as much light upon
plants as upon animals.

Lviii. By thefe exhortations, fuggefted
by an unfeigned defire of attaining truth, and
extending the limits of botannical knowledge,
I wifh to induce naturaliftsto ftudy in a more
philofophical manner the natural hiftory of
plants. The ligneous fpecies have, it is
true, been much illuftrated by the profound
enquiries of Grew, Malpighi, Hales, Du-
harnel, and Bonnet ; but the herbaceous
kinds fo much exceeding the others in num-
ber, and fo deeply interefting to mankind,
on account of the fuftenance they afford,
have been hitherto almoft totally neglected.
We have at moft a bare nomenclature, i'n
w^hich their different parts are defcribed ac-
cording to the fyftem adopted by the author.
I do not on this account condemn nomencla-
tures ; the necefTity of them is evident, fmce
it is impofTible to enter upon a rational invef-
tigation of plants before we are acquainted
with them ; and we cannot be acquainted

Vol. II. Ff with

434 UISSERTATIOl* TIT.

with them without the fcience of names (^).
I obferve only, that nomenclature ghding
along the furface of things^ is incapable of
furniihing fuch informationy as- \ti\\ fatisfy
the curioiity of the profound enq^uirer, and
advance our knowledge of the vegetabk
kinedom. The bodies of Nature are not
fnnple, but exceedingly complex ; Mufchen-
brock juftly compares them to^a clocks eon-
hfting of many wheels, and enclofed in a
cafe, v/hich prevents us from obtaining a
view of the fize and mutual dependency of
the wheels, and the various acflions of the
fprings. To fee, therefore, the internal
parts, and underftand them properly, it be-
comes neceffary to open the cafe: we muft
do the fame with refpe(5l to natural bodies,
and not be contented with barely infpeding.
the outfide, bat endeavour to penetrate fur-
ther, and inveftigate the wonders lying with-

{a) Befidcs beirvg obliged to learn the nonjenckture^
(whence it may be called the grammar of natural hifrory, and
thofe who teach it the grammarians) we are under the neceffi^y
of ufing it when we write, if we wifh to be generally under*'
ilood. Thusy in treating of plants and animals, unlefs they
haopen to be the moft common of all, it would appear, that
at prefent we cannot do without Linnaeus, If, at leall, wc
make ufe of the names in his Syfiema Natm-ay whatever glar-
ing defedls that work may contain, we are fure of being under-
flood by all Europe, I faid plants and animals ; {qt/oJ/jIs Wff
"ufe-Cronfledt and Wallerius> as the clafiical authors.

DISSERTATION III. 435

in. When the firft mineralogifts charac-
terifed the produdions of the foffil kingdom,
by difference in colour, in tranfparency,
opacity, by rough nefs or fmoothncfs, by
their granulated or fibrous ftrucflure, &c.
they held out only fuperficial, vague, and,
for the moft part, fallacious notions. Be-
fore they could be properly underftood, it was
neceffary that chemiftry fhould fearch thefe
produ(ftions by its analyfis. What this
fcience has done for foffils, anatomy has per-
formed for animals. We cannot but acknow-
ledge the greateft obligations to Swammer-
dam, Redi, Vallifneri, Reaumur, Lyonet,
Daubenton, and, above all, in the clafs of
infeds, to the immortal Malpighi, w^hofe
diflertation on the filk-worm is a tiillie of
difcoveries, and may be juftly coniidered as
alone fuperior to all the nomenclatures of in-
fects hitherto publifhed. I could wifh that
the fame attention, which fo many able na-
turalifls have beftowed upon refearches con-
cerning foflils and animals, was paid to her-
baceous plants. Their o^conomy, the prin-
cipal object of natural hiftory, ought, above
all, to be the aim of our enquiries. But it
will be impolTible to fulfil fuch an intention,
till a careful examination has been made,
both of their internal and external ftruc--

F fa ture.

43^ DISSERTATION 111.

ture {a) . I am aware, that refearches of this
nature require quicknefs of apprehenfion,
pertinacity of attention, fertility of rcfources,
exadlnefs of judgment, the utmoft vigilance
in noticing the phaenomena, and no lefs faga-
city in diilinguifhing them^ thefe requifites
do not feem indifpenfably ncceffary in the
learned nomenclator, who is generally con-
fpicuous chiefly for memory ; and this is the
true reafon why, at a time when we are rich
in nomenclators, we are poor, nay beggars,
in obfervers. But it is only by fuch laudable
exertions, and fuch valuable accompHfh-
ments, that v/e can hope to advance any far-
ther in this noble fcience, and to increafe the
ftores of ufeful knowledge. I cannot, there-
fore, but fet an higher value upon the genius

{a) Thofe who, from a defire to ferve the public, and to
contribute to the progrefs of human knowledge, fliall apply to
the lludy of plants, and indeed of minerals and animals alfo,
would do well, in my opinion, to follow the example of Erxle*.
ben, a late celebrated academician of Gottingen. Mr.
Kceftner, Prefident of that refpeftable academy, draws, in his
elogy, the following exemplary charader of him, and iubjoins
a very juftrePieclion. *' Hilloriam Naturalem, quam vocant,
judicabat (Erxleben) animalium, plantarum, foflilium, non
cataiogum efTe, fed phyficam. Itaque horum corporum llruc-
turam, analyilm, proprietates, ufus docait, non negleftis ta-
men notis quarum ope velut in indices poffent referri. Quos
indices folos qui memoriae mandant aut ad evolvendos illos oia-
nus habent exercitatas, frullra fibi perfuadentj librum ipfum
Na.tur^ fe tenere."

of

DISSERTATION III. 437

of thofe naturallfts, who confine their atten-
tion to Ibme part of natural hiftory not yet
fufficiently elucidated, than upon the art of
thofe, who only employ themfelves about no-
menclatures ; and I have the pleafure of
agreeing in opinion with thofe great men,
whofe moft earneft wifh is the greateft pof-
fible improvement of fcience, and who, while
they recommend it, with patriotic zeal, to
others, advance it themfelves in their im-
mortal produdlions. Not that thefe illuf-
trious WTiters defpife nomenclature, which is
fo neceifary, that it may be called the key of
the three kingdoms^ but they confider the
purfuits of nomenclators as not of the moft
ufeful tendency, becaufe the defire of com-
prehending, in voluminous nomenclatures,
like fo many Briareufes, the whole of Na-
ture, as more than one have attempted, feems
to them equally prefumptuous and puerile.
If Men would go about to difcover things,
and not words ^ if they would inveftigate
Nature, and bring to light fome part of her
inexhauftible ftores, they would render far
greater fervice to the fcience which they cul-
tivate, and deferve better of the republic of
letters. Left this reprefentation fhould ap-
pear exaggerated, I will adduce, from
among many refpedtable authorities which-

F f 3 are

DISSERTATION III.

are at hand to confirm it, thofe of the in-
comparable d'Alembert, and of the fubhme
contemplator of Nature. '^ We by no
means wilTi to refemble that tribe of natu-
raUfts, who have been fo juflly cenfured by
a modern philofopher ; inceflantly employed
in dividing the productions of Nature into
genera and fpecies, they fpend in fuch labours
the time which would much better be dedi-
cated to the ftudy of their properties." Such
are the exoreffions of the former in that moft
n:iaftet']y produdlion, the Preliminary Dijfer-
tat ion to the E?2cyclop(^dia, I fliall conclude
wdth the words of the latter. '' What
ought we to think of thofe pompous nomen-
clatures y which are arrogantly offered to us as
the Syftem of Nature ? They immediately
fuggeft the idea of a fcholar, who attempts
to form the index of a large folio, after hav-
ing read only the title and a few of the firft
pages. And are we in poffefiion of even the
iirft pages of the book of Nature ? How
many paffages do they contain which we do
jiot .underiland, and of which the hidden
meaning probably contains intereiling truths ?
I wifh not to extirpate nomenclators ; they
ilrive to give our knowledge feme arrange-
^ mentj but I will venture to fay, that a mere
aomenclator will never make any great dif-

covery^

DISSERTATION IH, 439

covery. I will add, that I fet an higher
valne upon a good treatife concerning a fingle
inled, than upon a whole entomological
nomenclature. — Study the admirable hiftory
of the polype, perufe the fine memoirs on
infeds, and then compare the ufefulnefs of
thefe producftions with that of the m.oft
boafted nomenclatureSc Of which would
you fooner chufe to be the author? Which,
think you, imply m.ofl fagacity, genius, and
invention, and have the greateft tendency to
improve anatomy and natural hiftory? We
ought, in my opinion, not to be fo anxious
to make a catalogue of human knowledge, as
to increafe it. Let us colletl more materials
before we think of erecting a temple to Na-
ture. She will elfe refufe to dwell in it. In-
fteadof correfponding to her majefty, it will
only be proportional to the meannefs of the
architedt (^)/'

(a) Contemplation de la Nature.

END OF DISSERTATION III

Ff4 APPEN.

[ 441 ]

APPENDIX.

AN ABRIDGEMENT OF MR. DEMOUR S OB-
SERVATION IS TO BE FOUND IN THE
FRENCH MEMOIRS FOR I74I, p. 28.
IN THE MEM. FOR I778, PRINTED IN
I781, p. 13, WE FIND THE ACCOUNT
IN HIS OWN V/ORDS. THE TITLE IS,
^' OBSERVATION DE DEUX ANIMAUX,
DONT LE MALE ACCOUCHE LA FE-
MELLE.

THE eulogies of Naturallfts upon the in-
duftry of animals are boundlefs. It
has been pretended, that man is^ indebted to
them for the ufeful arts ; and fome are ex-
travagant enough to affirm, that even the
moft abftradled faiences have been borrowed
from brutes [a). According to Pliny and
feveral other naturalifts, the idea of bleeding
was fuggefted to phyficians by the hippopo-
tamus; and that of injedion by the ftork,
which, on account of the great fervices it
rendered them, was formerly worihipped by

{a) Gio'vatini Bonnifacio, I'arti liberali e mechaniche, come
fiano fiate dagli animali irrationali, agli Kvjomini dimolirate.

the

442 APPENDIX.

the Egyptians. The bear and the dog
pointed out the advantage of emetics; the
former by fvvallowing ants, the latter by eat-
ing the leaves of dog's grafs- Happily for
medicine, the fad: recorded in this Memoir,
was unknown to thefe naturaliils, otherwife
they would not have failed to afcribe the ori-
gin of the art of midwifery to the animal ii>
q:uefLipn.

One evening during the dog-days, I ob-
ferved near fome fteps by the great bafon ia
the king's garden, in which I at that time
occupied the onice of demonftrator, and
keeper of the cabinet of Natural Hiftory,
two land toads of the fm.aller fpecies [a) m
the a<5t of copulation* I faw that the male
frequently moved his hind legs ; a defire to
difcover the caufe of thefe movements led me
towards the placcp where I was furprized by
two phsenomena, which I believe have not
been hitherto noticed. The firft was the
difficulty with which the female brought
forth her eggs, which was fuch that fhe ab-.
folutely required foreign aid, what no other
animal with which we are acquainted does.
The fecond phenomenon was the efforts made
hj the male to extrad the eggs with his hind

{a) Rubsta uiinort GefnerL

feet.

APPENDIX. 44^

feet, and his thus performing the ofEce of an
a'ccoucheur.

I could not conceal my fatisfacElion at a
fpedacle fo uncommon. My attention re-
doubled, and I feated myfelf quietly on
the ground, in order to obferve more ac-
curately; and efpccially to watch whether the
male impregnated the eggs as he extradled
them.

To underftand the operation completely,
it muft be remarked, nrfc, that the fore as
well as hind feet of thefe animals are divided
into feveral toes, by the help of which the
male draws the eggs out of the vent of the
female.

Secondly, that thefe animals copulate hke
frogs, i. e. the male gets upon the female's
back, and em.braces her v/ith his fore feet.
In the frog the feet are long enough to clafp
the female completely, wdiereas in the toad
they reach only to the fide of the breaft,
againft w^hich the animal preiTes with fuch
force, that an ecchymoiis often takes place
before he quits his fituation.

I mull: obferve in the third place, that the
fcggs of this fpecies of toad confifi: of a flrong
membranous cover, within which the em-
bryo is contained. The eggs are about two
lines long, and of an oblong iliape ; they are

connecfted

jf'44 A P P E N D I X.

connecled by a iliort and flrong cord. A
pretty jufl: idea of theie eggs rnay be con-
veyed, by comparing them to a necklace, of
which the beads lie at about half their own
length from each other. They are difcharged
at the vent, becaufe the receptacle in which
they were contained, opens into the lower part
of the rectum.

There is reafon to fuppofe, that the firft
egg is expelled by the exertions of the fe-
male, and that the male extrads the reft.
He performs his office v>^ith an addrefs that
one would not txpcS: in an animal naturally
fo aukward. When his motions drew my
attention, he had extracted the fecond, and
was endeavouring to extract the fucceeding
egg. The firft was fixed between the toes
uf the right foot, by the filament which
conneds it with the fecond, and it was by
ftretching out the foot, that he drew tliem
from the anus of the female, which con-
tinued motionlefs during the whole time.
He tried to lay hold of the cord with his left
foot, and made feveral attempts before he
fucceeded. My prefence undoubtedly fome-
times drew off" his attention : for he would
now and then ftop fuddenly, and look at me
¥/ith an air expreffive either of inquietude or

fear i

A P P E N D IX. 445

fear: then he would refume his employment
with frelh alacrity, and foon relax again fo
much in his ardour, as to feem irrcfolute
whether he fliould proceed or not. The fe-
male alio teflified her difquiet by movements
that difturbed the operations of the male,
but {lie never feemed defirous of returning
to the ilation under the ftone which Ihe had
quitted.

At laft, whether from my filence and im-
mobility, or from the urgency of the cafe,
the female became ftill, and the male re-
fumed his employment : he foon laid hold of
the cord with his left toes, and now drew it
out with both feet, by extending them gently.
When he had ftretched them out as far as he
could, he withdrew the left foot, without
quitting the eggs that adhered to it, and con-
tinued to extr^^dt with the right alone. But
here his difficulties recurred a fecond time.
The portion of cord that lay between the
middle fingers of the right foot, often pre-
vented him from getting hold of a new part
-of the cord with that foot. He made feveral
ejfforts without fucccfs, and flopped of a
fudden oftener than once. I was afraid, that
the movements of my head were the caufe
©f thefe interruptions, and I then fat mo-

tionlefs.

r

446 APPENDIX.

tionlefs, and held in my breath. Sometimes
I was incHned to attribute them to the diffi*
culty of the operation itfelf ; this tempted
me to affift the animal, but I forbore, for fear
of breaking off the procefs. My attention
had hitherto been divided between two ob-
je(fls j while^ on the one hand, I admired
the dexterity of the male, I watched on the
other, whether he bedewed the eggs with
femen as he extradied them, but as yet I
could not fee any appearance like this, though
it feemed abfoiutely neceffary to the fecunda*
tion of the eggs, and was, at the fame time,
the chief objed: of my curiofity: I thought
the want of light might prevent me from
feeing it, and therefore, at all hazards, fct
them on my hand, that I might infped: them
more clofely.

This change of fituation put a flop to the
procedure of the male for a few moments j
but the urgent neceffity for delivering the
female, doubtlefs made him colledl courage
to refume his employment. I now tried
only to obferve, whether the male impreg-
nated the eggs as he drew them out ; but
notwithftanding all my folicitude to fee
a phaenomenon, of which the waters
newt had before furnifhed me with an
/ example.

A p p E N D I :t. 447

example (a), I could not perceive any thing
like what I expeded. The evening now
clofed in, and after obfcrvine: them for
about half an hour, I was forced to fet them
down in the place from which I had taken
them.

My meeting with thefe animals was one of
thofe fortunate occurrences, of which a na-
turalift alone can ellimate the value. It af-
forded me the view of a facl, fmgular and
hitherto I believe unnoticed. The affiftance
yielded by the male I faw diftindly ; but it
was quite otherwife with refped: to the other
part of the obfervation. I could not, with
all my attention, perceive any thing like what
Swammerdam faw in frogs, viz- that after
forty days of coitioi> the male impregnates the
eggs as the female difcharges them, by be-
dewing them with femen.

Though I could not perceive this irrora-
tion, yet there is reafon to fuppofe, not only
that it is neceflary for the fecundation of this
fpecies of fry, but alfo that it takes place in

{a) The female newt is impregnated without -coition. The
male keeps at about the diftance of an inch above the female,
and throws out the feminal liquor upon her fides, which ren-
ders the water a little turbid. This obfervation is to be found
at the end of the firll volume of my tranllation of the Edin-
burgh Eifays,

th^

44^ APPENDIX.

the fame manner as in the frog. The exadl
conformity between the ftrudlure of the in-
ternal parts of thefe animals, between their
mode of coition and their embryos, which
in each kind pafs through the jftate of tadpole
before they attain the form of frog or toad,
ftrongly confirms this conjedlure. I fhould
therefore fuppofe, that the male performs
this fundion at fome other time. He pro-
bably, as well as the frog [a), bedews all the
eggs at once, which he can not accomphih
when he has them entangled about his feet.
In truth, the wafle would be too great if he
impregnated them fucceilively, and in this
cafe a great quantity of femen would fall on
the ground, and my hand, upon which the
male operated for about a quarter of an hour,
muft have received fom^.

This obfervation apprized me of a miftake
I had formerly committed. During the two
laft years of M. Duverney's life, I affifted
him in his anatomical labours ; and I had
once occafion to feek by candle-light for
newts, w^hich the heat and drought of the
feafon confined in their places of retreat in
the day-time. Near a refervoir, confifting

(«) How far this fuppofitlon is to be admitted, the reader
luaj learn from the firil of the preceding differtations. T.

A P P E N D I X.\ 449

of a barrel that projedted eight or ten inches
above the furface of the ground, I perceived
a toad of the fpecies above-mentioned, with
a bundle of eggs on his back. The animal
traverfed round the barrel to no purpofe ;
the edge w^as too high for him to difcharge
his burden into the water. I took it up with
an intention to relieve its diftrefs, by throw-
ing it into the water; in an inftant I felt
fomething move in my hand, and upon
bringing the light near I perceived feveral
little tadpoles juft come out of their enve-
lope ; they were very lively, and as full
formed as tadpoles of frogs that have loft
their tail, and which confequently have
quitted their cover fifteen days. The cord
of eggs was fo entangled in the hind fc^t,
that the animal could make but very fhort
fteps. At that time I fuppofed it to be the
female, but the obfervation which I have
now rekted proves, that it muft have been
the male which is charged with the cares that
attend incubation. Nature, in the prefent
inftance, has divided the toil that relates to
the progeny equally between the two fexes.
The female has the burthen of the eggs be-
fore delivery, and likewife fupports the male
upon her back, probably for forty days, as
Vol. 11. Gg in

450 appendix:

in the frog and water toad. The male, in
his turn, delivers the female, and carries the
eggs on his back till the time of the exclu-
fion of the tadpoles, which happens fooner
or later, according to the feafon, and he
then depofits them in a proper place: He
throws himfelf into thefirft water he meets,
and is frequently the vidtim of paternal at-
tention. If he gets into a place whence he
cannot eafily find his way out, he perifhes
in a few days, as I have feen in many
inftances. This fpecies, which Ol. Ja-
cobseus confiders as the Rana fhrynoidesoi
Gefner, and which fome authors call Ru^
beta minory in order to diftinguifh it from
the common toad, which they denominate
Riiheta major^ is incapable of living in water
after he has once quitted it. He paffes
the former part of his life in water, and the
latter upon dry land. This, according to
Gefner, was known to the ancient naturahfts,
who affert the fame thing of the common
•frog.

The fpecies here mentioned quits his en-
velope in the form of a tadpole without a
tail; at this time it has gills, and lives in
water like fifhes : there it continues till the
gills begin to be effaced, which happens as

^ ^ foon

APPENDIX. 45 1

foon as the fore-feet burft through the mem-
brane which contained them : when the ani-
mal can walk or jump it feeks a different ele-
ment, and quits the water before its tail is
entirely ^effaced.

Gg2 Discoveries

45^ APPENDIX.

l)lSCOVERIES ON THE SEX OF BEES, EX-
PLAINING THE MANNER IN WHICH
THEIR SPECIES IS PROPAGATED ;
WITH AN ACCOUNT OF THE UTILITY
THAT MAY BE DERIVED FROM THOSE
DISCOVERIES BY THE ACTUAL APPLI-
CATION OF THEM TO PRACTICE. By

Mr. John Debraw, apothecary to
Addenbrqjok's hospital at Cam-
^ridge> and member of an oeco-

NOMICAL SOCIETY IN THE PRINCIPA".

LiTY OF Liege, in Westphalia.
Communicated by the Rev. Nevil
Maskelyne, b. d. f. r. s. an©
astronomer royal.

Read Nov. 21, 1776.

THE republic of bees has at all times
gained univerfal efteem and admira-
tion : their culture, an object fo worthy of
our attention, has attracted and ftill does en-
gage that of naany of the learned, and has
arrived at a confiderable degree 6f improve-
ment of late years -, but their mode of pro-
pagating their fpecies, feems to this day to

have

APPENDIX. 45^

have baffled the ingenuity of ages in their
attempts to difcover it. The moft ikilful
naturaHfts have been ftrangely mifled in
their apinion, that the bees, as well as the
other tribes of animals, are perpetuated by
copulation -, though they acknowledge that
they have never been able to dete(fl them m
the adl.

Pliny, who was like wife of the fame
opinion, that in this particular they do not
differ from other animals, obferves, *' Apium
coitus vifus eft nunquam." Swammerdam,
that fagacious obferver, having never been
able to difcover it, entertained a notion, that
the female or queen bee was fecundated with-
out copulation ; that it was fufncient for her
to be near the males ; that a vivifying ciitra,
exhaling from the body of the males, and
abforbed by the female, might impregnate
her eggs. At laft the incomparable Reau-
mur thought he had in a great meafure re-
moved the veil, and brought their manner of
generating nearly to a proof. This part of
phyfics has been the principal objed: of my
refearches for feveral years paft, having been
infenfibly engaged in it by the pleafure I took
in fo curious an enquiry ; and although this
purfuit has been attended v/ith more difficul-
ties and embarraffments than can be well

G g 3 imagined^

454 APPENDIX.

imagined, I have not been difcouraged, and
have carefully avoided launching into con-
jedures. To introduce a new fyftem in the
dodlrine of bees, which in a great meafure
contradicts all former received opinions, re-
quires, previous to its appearance, every fanc-
tion the various experiments, fuccefsfully re-
peated, can poffibly give it. The refults of
thofe experiments, made in all glafs-hives,
which carry with them an intire evidence,
afford fufficient reafons to affert, that bees
belong to that clafs of animals among
which, although they have fexes, a true co-
pulation cannot be proved -, and that their
ova, like the fpav^n of fifties, moft probably
owe their fecundation to an impregnation from
the males, as will appear in the fequel of this
narrative..

I am not a little pleafed . to find, that the
celebrated Maraldi had fuch a notion, and I
lament his neglecting to confirm it. He fays,
in J^is Obfervatic7is upon BeeSy in the Hifcory
of the Academy of Sciences for the year
1712, p. 332: '^ Nous n'avons pu decouvrir
jufqu' a prefent de quelle maniere fe faite
cette fecondation, fi c'eft dans le corps de la
femielle, ou bien fi c'eft a la mianiere des poif-
fons, apres que la femxclie, a pofe fes ceufs :
la matiere blanchatre dont V oeuf eil envi-

ronne

APPENDIX, 455

ronne au fond de I'alveole peu de temps apres
fa naiflance, femble conforme a la derniere
opinion, auffi-bien que les remarques faites
plufieurs fois d'un grand nombre d'oeufs qui
font reftes infeconds au fond de Talveole
autour defquels nous n'avons point vu cette
matiere." — *' We never yet were able to
difcover in what manner this fecundation rs
performed ; whether it is in the body of the
female, or whether it is after the manner
of fifhes, after the female or queen-bee has
depoiited her eggs : that liquid whitilL fub-
flance, with which each egg is furrounded at
the bottom of the cell, a little while after
its being laid, feemingly eftablifliing this '
laft opinion, as well as the frequent remarks
made of a great number of eggs remaining
barren in the cell, round which we could
not fee the above-mentioned whitifli fub-
ilance/' .

This ingenious naturalift, by a nice exa-
mination of the ftrufture of the drones, had,
as well as Swammerdam, difcovered fome
refemblances to the male organs of genera-
tion ; and from thence conjedtured, they Vv^re
the males of the bee-infed:; but he owns,
with the reft, that he never could difcover
them in the adl of copulation.

Gg4 Having

45^ APPENDIX.

Having flood the trials of fo many prying
eyes in every age, the bees, as has been ob-
ferved by an ingenious author, had gained
the character of an inviolable chaftity, till
Reaumur blafted their reputation. He makes
the queen no better than a Meflalina {a) ;
though he could fee no more than what
would raife a mere jealoufy or generate fufpi-
cions.

In order to be the better underftood in the
relation of my own experiments on the fe-
cundation of bees, I here premife the out-
lines of the opinions adopted by the above-
mentioned naturalifts on that head. They
affert, that the queen is the only female in
the hive, and the mother of the next gene-
ration j that the drones are the males by
Xvhich fhe is fecundated ; and that the work-
ing bees, or bees that collect wax on the
flowers, that Jcnead it, and form from it the
combs and cells which they afterwards fill
with honey, are of neither fex.

But of late Mr. Schirach, a German na-
turalift, has given us a very different view of
the clafTes that conflitute the republic of
bees, in an ingenious publication in his own
language, under the title of The Natural

(a) yid. Juvenal^ Sat, vi. ver, 128.

Hifory

APPENDIX. 457

Hi /lory of the ^ee?2 of the Bees^ which has
. been fince tranflated into French ; an account
of which has been given in the Monthly
Review, from which I beg leave to rekt^
the author's doftrine with regard to the
working-bees only ; the quality and fundlions
ef the drones being points which do not ap-.
pear to be yet fettled by Mr. Schirach him-
felf. He affirms, that all the common bees
are females in difguife, in which the organs
that diftinguhh the fex, and particularly the
ovaria, are obliterated, or at leaft, through
their exceffive minutenefs, have not yet been
obferved : that every one of thofe bees, in
the earlier period of its exiflence, is capable
of becoming a queen-bee, if the whole
community fhould think proper to nurfe
it in a particular m^anner, and raife it to that
rank. In fhort, that the queen-bee lays
only two kinds of eggs, viz. thofe that are
to produce the drones, and thofe from which
the wx)rking-bees are to proceed.

The trials made by Mr. Schirach feem to
evince the truth of his conclufions in the
moft fatisfadtory manner, lingular as they
appear to be at firft fight ^ and indeed in my
own judgment, from the conftant happy
refult of numerous experiments, which I
b^gan near two years before Mr. Schirach's

publication.

458 APPENDIX.

poblication, and repeated every feafon fince,
I am enabled to pronounce on their reality.

Chance, I own, befriended me in that
difcovery, whilil I was moft anxioufly en-
deavouring to aicertain the ufe of drones. It
was in the fpring of the year 1770, that I,
for the firft, difcovered what Maraldi had
only conjeftured, I mean the impregnation of
the eggs by the males ; and that I was made
acquainted with the difference of fize in the
drones or males, obferved by Maraldi in his
Obfervations upon BeeSy inferted in the Hiftory
of the Royal Academy of Sciences for the
year 1712, p. 333, in thefe words :

** Nous avons trouve depuis peu une
grande quantite de bourdons, beaucoup plus
petits que ceux que nous avions remarque
auparavant, & qui ne furpaffent point la
grandeur des petites abeilles ; de forte qu'il
n'auroit pas ete aife de les diftinguer dans
cette ruche des abeilles ordinaires, fans le
grand nombre que nous y en avons trouve,
11 fe pourroit bien faire que dans les ruches
ou Ton n'a pas trouve de gros bourdons, il y
en eut de ces petits, & qu'ils y aient ete con-
fondus avec le refte des abeilles, lorfque nous
ne favions pas encore qu'il y en eut de cette
taille," — *^ We have of late found a great
quantity of drones, much fmaller than thofe

we

APPENDIX. 459

we had formerly obferved, and which do not
exceed in fize the common bees ; fo that it
would not have been eafy to diftinguifli them
in that hive from the common bees, had not
the quantity of them been very confiderable.
It might certainly have happened, that in
thofe hives, where we have not been able to
difcover large drones, there were a great
number of thofe little ones, which may have
been intermixed among common bees, when
we were yet ignorant that any fuch fmall drones
were exifting/'

Reaumur himfelf, p. 591, of his Natural
Hiftory of InfeAs, fays, ^' We have likewife
found drones that were no bigger than the
common bees/*

They have notwithftanding efcaped the
obfervation of Mr. Schirach, and of his
friend Mr. Hattorf, member of an academy
in Lufatia, who, in a memoir he prefented in
the year 1769, annihilates entirely the ufe of
drones in a hive; and advances this lingular
opinion, that the queen -bee of a hive lays
eggs which produces young ones, without
having any communication with the drones.
For what purpofe fliould wife Nature then
have furniflied the drones with that large
quantity of feminal liquor ? To what wk fo

large

4.6o APPENDIX.

large an apparatus of fecundating organs, fo
well defcribed by Reaumur and Maraldi? .

But I beg leave to remark, that thofe
gentlemen feem to have drawn too hajfty con-
clufions from their experiments, in rejeding
the drones as bearing no fhare in the propa-
gation of thofe infedts. Their obfervations,
that hives are peopled at a time of the year
when there are no drones in being, is no
ways conclulivej as it is evident, that they
had {cQn none but drones of a larg& fize, their
fiJence on the difference in the fize of them
juftifying my remark. But to refume the
narrative of my experiments : I had watched
my glafs-hives (a) with indefatigable atten-
tion from the moment the bees, among
which I had taken care to leave a large
number of drones, were put into them, to
the time of the queen laying her eggs, which
generally happens the fourth or fifth day. I
obferved the firft or fecond day (always before
the third) from the time the eggs are placed
in the cells, that a great number of bees,
faflening themfelves to one another, hung
down in the form of a curtain, from the top
to the bottora of the hive, in a fimilar manner
they had done before at the time the queen

(a) Glafs-hives were ufed in preference to boxes, for a pur-
pofe wo obvious to need explaining.

depofited

A p p E 1* D I X. 46r.

depoiited her eggs ; an operation which (if
we may conjedlure at the inftindts of infects)
feems contrived to hide what is tranfadling:
be that as it will, it anfxvered the purpofe of
informing me that fomething was going for-
ward. In facl, I prefently after perceived
feveral bees, the fize of which, through this
thick veil, (if I may fo exprefs myfelf ) I could
not rightly diftinguiili, inferting the pofleriur
part of their bodies each into a cell, and
finking into it, where they continued but a
little while. After they had retired, I faw
plainly with the naked eye a fmall quantity
of a whitifh liquor left in the angle of the
bafis of each cell, containing an egg : it was
lefs liquid thaQ honey, and had no fweet tails
at all. Within a day after, I found this
liquor abforbed into the embryo, which on
the fourth day is converted into a fmall worm,
to which the working-bees bring a little
honey for nourifhment, during the firft eight
or ten days after its birth. After that time
they ceafe to feed them; for they fhut up
the cells, w^here thefe embryos continue in-
clofed for ten days more, during which time
they undergo various changes too tedious here
to defcribe.

To evince the reality of this obfervation,
and to prove that the eggs are fecundated hy

tha

4^2 appendix;

the males, and that their prefence is neceflary
at the time of breeding, I proceeded to the
next experiments. They confifted in leaving
in a hive the queen with only the common
bees, without any drones, to fee whether
the eggs fhe laid would be prolific. I ac-
cordingly took a fwarm, fhook all the bees
into a tub of water, and left them in it till
they were quite fenfelefs, which gave me an
opportunity to diftinguifh the drones without
any danger of being ftung. After I had re-
covered the working-bees and their queen
from the ftate they were in, ^by fpreading
them on brown paper in the fun, I replaced
them in a glafs-hive, where they foon began
to work as ufual : the queen laid eggs, v/hich
I little fufpeded to be impregnated, as I
thought I had feparated all the drones or
males, and therefore omitted watching the
bees 5 but at the end of twenty days (the
ufual time of their hatching) I found to my
furprize fome of the eggs hatched into bees,
others withered away, and feveral of them
covered with honey. I immediately inferred
that fome of the males, having efcaped my
notice, had impregnated only part of the
eggs 5 but, in- order to convince myfelf of
the truth of my fuppofition, I thouglit it
neceiFary to take away all the brood-comb

that

APPENDIX. 463

that was in the hive, in order to oblige the
bees to provide a frefh quantity, being fully
determined to watch narrowly their motions
after new eggs fhould be depoiited in the
cells. This was done accordingly, and at
laft the myftery was unravelled. On the
fecond day after the eggs were placed in the
cells, I perceived the fame operation which
I have related in a former experiment ; I
mean, the bees hung down in the form of a
curtain, while others thruft the pofterior part
of their body into the cells: I then intro-
duced my hand into the hive, broke off a
piece of the comb containing two of thofe
infe(fls, and kept them for examination. I
found in neither of them any fting, (a cir-
cumftance peculiar to drones only) ; and
upon diffed:ion, by the help a Dolland's mi-
crofcope, difcovered in them the four cylin-
drical bodies, which contain the glutinous
liquor of a whitifh colour, obferved by Ma-
raldi in the large drones.

Having till then never obferved any dif-
ference in the fize of drones, I immediately
perufed the memoirs on bees, publifhed by
Meff. Maraldi and Reaumur, and found that
they had remarked it frequently. I have
inferted, in a preceding page, the fubftance
of their obfervations on that head, as taken

from

464 'appendix.

from their writings. The reafon of that
difference muft, I doubt, be placed amongll
other arcana of nature. I found myfelf,
therefore, under a neceflity, in my next
experiments, to be more particular in deftroy-
ing the males, even thofe which might be
fulpeded to be fjch.

I once more immerfed all the- fame bees in
water ; and, when they appeared to be in a
fenfelefs ftate, I gently preifed every one of
them between my fingers, in order to dif-
tlnguifh thofe armed with flings from thofe
which had none, which lafl I might fufpedl
to be males. Of thefe I found fifty-feven,
exadlly of the fize of common bees, yielding
a little whitifh liquor on being preffed be-^
tween the fingers. I killed every one, and
replaced the fwarm in a glafs-hive, where
they immediately applied again to the work
of making cells ; and on the fourth or fifth
day, very early in the morning, I had the
pleafure to fee the queen-bee depofiting her
eggs in thofe cells; which fhe did by placing
the poflerior part of her body in each of them..
I continued on the watch mofl part of the
enfuing days, but could difcover nothing of
what I had feen before.

The eggs, after the fourth day, inflead of
changing in the manner of caterpillars, were

found

APPENDIX, 465

found in the fame ftate they were in the firft
day^ except that fome o^ th?m were covered
with honey. But a very Angular event hap-
pened the next day about noon : all the bees
left their own hive, and were feen attempt-
ing to get into a neighbouring common hive,
on the ftool of which I found their queen
dead, having, no doubt, been flain in the
engagement. The manner in which I ac-
count for this event is as follows : the great
deiire of perpetuating their fpecies, which is
moft obfervable in thefe infects, and to which
end the concurrence of the males feems fo
abfolutely neceifary, made them defert their
own habitation, where no males were left, in
order to fix their refidence in a new one, in
whicji, there being a good ftock of males,
they might the better accompliih their pur-
pofe. If this does not yet eftablifh the
reader's faith of the neceffity of the males
bearing a fhare in the fecundation of the ova,
the next experiment cannot, I prefume, fail
to convince him.

I took the brood comb which, as I ob-
ferved before, had not been impregnated; I
divided it into two parts ; one I placed under
a glafs-bell, N° i . with honey-comb for the
bee's food; I took care to leave ^ queen, but
no drones, among the commQU bees I con-

VoL.IL Hh fined

A P P E N D I X,

fined in it. The other piece of brood comb
I placed under another glafs-bell, N' 2'. with
a few drones, a queen, and a number of com-
mon bees, proportioned to the fize of the
glafs i the reft I difpofed of as before. The
refult was, that in the glafs, N"^ i . no im-
pregnation happened : the eggs remained in
the fame ftate they were in when put into the
glafs; and, upon giving the bees their li«
berty on the feventh day, they all flew away,
as was fc>iind to be the cafe in the former ex-
periment : whereas, in the glafs, N° 2. I faw,
the very day after the bees had been put un-
der it, the impregnation of the eggs by the
drones in every cell containing eggs; the bees
did not leave their hive on receiving their li-
berty ; and, in the courfe of twenty days>
every egg underwent all the above-mentioned
neceffary changes, and formed a pretty nu-
merous young colony, in which I was not a
little ftartfed to find two queens.

Fully fatisfied concerning the impregna-
tion of the eggs by the males, I defifled for
the prefent from any further experiments on
that head, being exceedingly anxious to en-
deavour to account for the prefence of this
new queen,

I conjedured, that either two queens, in-
ftead of one, mull have been left among the

bees

APPENDIX. 467

bees I had placed under that glafs; or elfe,
that the bees could, by fome particular means
of their own, transform a common fubje(^
into a queen.

In order to put this to the teft, I repeated
the experiment with fome variation. I got
four glafs-hives blown flat, which I thought
preferable to the bell-fliaped ones I Tiad ufed
before, as I could with thofe better examine
what was going forward. I took a large
brood-comb from an old hive, and, after
having divided it into feveral pieces, I put
fome of them, containing eggs, worms, and
nymphs, with food, viz. honey, &c, under
each of the glaffes ; and confined within each
a fufficient number of common bees, among
which I left fome drones, but took care that
there fliouid be no queen.

The bees finding themfelves without a
queen, made a ftrange buzzing noife, which
lailed near two days 3 at the end of w^hich
they fettled and betook themfelves to work :
on the fourth day I perceived in each hive the
beginning of a royal cell, a certain indicatiofi
that one of the enclofed worms would foon be
converted into a queen. The conilrudion of
the royal cell being nearly accompliilied, I
ventured to leave an opening for the bees to
get out, and found that they returned as re-

H h 2 gular]y

A p p ;e N t> I x:

gularly as they do in common hives, and
ihewed no incUnation to defert their habita-
tion. But, to be brief, at the end of twenty
days I obferved four young queens among
the new progeny.

On relating the refult of thefe experiments
to a member of this univerfity, well conver-
fant in the natural hiftory of bees, he deemed
it neceffary that they fliould be repeated, in
order the better to eftablifh the truth of a
faft, feemingly fo improbable, that the eggs,
deiiined by Nature to produce neutral or com-
mon bees, fhould be transformed into females
or que';ins. He ftarted an objedion to me,
which, by the publication of Mr. Schirach
appearing a little time after, feems to have
been pointed out to that author alfo by Mr,
Withelmi, his brother-in-law, namely, that
the queen-bee of a hive, befides the eggs
\vhich ihe depofits in the royal cells, might
alfo have laid royal or female eggs, either
in the common cells, or indifcriminately
throughout the different parts of the hive.
He further fuppofed, that in the pieces of
brood-comb, which had been fuccefsfully
employed in the laft experiments for the pro-
duction of a queen, it had conftantly hap--
pcned, that one or more of thejfe royal eggs,

or

appendix; 469

er rather the worms proceeding from them,
had been contained.

But the force of his objedlion was removed >
foon after, by the fame fuccefs having at-
tended a number of other experiments which
I fmce made, an account of which would
take up too much room here; and this Gen-
tleman, together with Mr. Schirach's bro-
ther-in-law, was at laft brought to admit,
that the working-bees are in veiled with a
power of raifmg a common fubjecft to the
throne, when the community ilands in ne^d
of a queen; and that accordingly every worm
of the hive is capable, under certain circum-
flances, of becoming the mother of a genera-
tion : that it owes its metamorphofis into a
queen, partly to the extraordinary iize of the
cell, and its particular pofition in it; but
principally to a certain nourifhment appro-
priated to the occafion, and carefully ad-
miniftered to it by the working- bees while
it is ia the worm-ftate, by which, and pof-
fibly other means as yet unknown, the de-
velopement and expanlion of the germ of the
female organs, previouily exifting in the em-
bryos, is effedted, and thofe differences in its
form and iize are produced, which after-
wards fo remarkably diflinguifli the queen
from the common w^orking-bees. And finally

H h 3 it

470 APPENDIX.

it appears evident, from the experiments
made by Mr. Schirach and mj^felf, that the
received opinion, that the queen lays a parti-
cular kind of eggs, appropriated to the pro-
duction of other queens, is erroneous/ I am
not a little flattered vi^ith the fimilarity of my
difcoveries with thofe of the ingenious Ger-
man naturalift, in proving the fex of the
common bees, although we fo widely differ
in what relates to the ufe of the males, whom,
as' we have i^^vi before, he imagines to be
quite ufelefs. I am alfo not a little pleafed
to find, that our experiments-on the produc-
lion of a queen from a common embryo agree
fo well. ' .

I iliall now beg leave to point out the ad-
vantage that may accrue to the public from
thefe obfervations, which is that of forming
artificial fwarms or new colonies ; or in other
words, of furnifliing the means to bring .on
a numerous increafe of thofe ufeful infeds :
an object of fome importance to this king-
dom^, as being the only means to prevent the
annual exportation of confiderable fams in
thepurchafe of wax, a great quantity of v/hich
is loft every feafon for want of keeping up a
fufficient flock of bees to collect it.

The practice of this new art, Mr. Schirach
tells us, has already extended itfelf through

Upper

APPENDIX. 471

Upper Lufatia, the Palatinate, Bohemia, Ba-
varia, Silefia, and even in Poland. In fome
of thofe countries it has excited the attention
and patronage of government ; and even the
emprefs of Ruffia has thought it of fuch im-
portance, that fhe has fent a perfon to Klein
Bautzen, to be inftrudied in the general prin-
<:iples, and learn all the minutice of this new
art.

The narrow^ limits of this paper do not per-
mit me here to give an account of Mr, Schi-
rach's ingenious obfervations. I beg leave
to refer the curious reader to the work itfelf,
which, with the reviewers, I wifh was tranf-
lated into the Englifh language, as it contains
many particulars highly deferving the notice
of the fpeculative naturalift, as well as of
thofe who cultivate bees either for profit or
amufement.

Hh4 PART

[ 472 I '

■i

PART OF A '

L E T T E R

(
FROM THE

ABBE' SPALLANZANI/

trO THE

MAR QJJ IS LUCCHESINI,

Chamberlain to the King of Prussia.

T WAS fome time ago favoured, by your
"*• means, with a letter from the king, I
had before been agreeably furprized by the
repeated inftances of efteem and kindnefs,
with which that great monarch has con-
defcended to honour me at different times :
but I now feel much greater fatisfadion than
ever, on account of his gracious acceptance
of my laft publication (^), which I humbly

(«) His DiiTertations,

offered

APPENDIX. 473

offered him by you. In confequence of his
command you made an extradl, which he had
the goodnefs to read, and to confider as not
unworthy of his royal approbation. Two
particulars, you inform me, efpecially drew
the attention of this acute philofopher : the
firft, my difcoveries refpefting the generation
of feveral amphibious animals. By thefe ob-
fervations he thinks, that the dodlrine of £/>/-
genejis is fully confuted, and that of the pre-
exiftence of germs eftabliflied, an opinion to
which he is much inclined. The other par-
ticular is, the artificial fecundation of various
animals. This made the deepeft impreffion
on his mind, as 1 collect from your following
expreffions : " But no part of your book ex-
cited fuch aftonifhment as that which treats
of artificial fecundation. On reading the
analyfis of it he thought of a thoufand expe-
riments, worthy of the notice of the natura-
lift, as to extend the difcovery from porticu-
lars to general, and to enlarge, if it be pofli-
ble, the kingdom of animated nature by new
colonies of various forts of mules." Thefe
two views are , certainly the moft interefting
of all which natural philofophy affords ; but
I now confider them as more interefting than
ever, fince they have appeared fo agreeable in
J;he eyes of this philofophic king. With re-

fped

A P f E N D I X.

fped: to the firftj I rejoice exceedingly with
the favourers of the pre-exiftence of germs,
among whom are included the moft judicious
naturalifts of the prefent age, that we are
joined with (o wife and great a monarch;
and I cannot but be proud of his glorious
approbation, fo graciouily accorded to my
difcovery.

With refpedl to artificial fecundation, the
fubjeft being, I prefume, w^orthy of your at-
tention, permit me to detain you a little while
upon it,--- And in the lirft place, a few words
concerning amphibious animals. Finding
that I had reaped in a field which I may term
niy own, I was tempted to revifit it, by the
hope of adding fome new ears to what I have
already gathered. After the publication of
my work I therefore made frefh experiments,
^vhich proved fortunate beyond all belief.
Words cannot exprefs the abundance of the
produce. I knew, by experience, that thofe
topics of natural hiftory, which we fuppofe to
be exhaufted by our induftry and patience,
when refnmed, prefent themfelves under new
and unexpected afpeds, w^hence refult either
new truths or ufeful confequences : all the
works of the fupreme Archited: being ftamped
with the feal of his infinite perfections, can-
not be exhaufted by human induftry. I will

not

APPENDIX. 475

not detain you with the particulars of my new
obfervations on the artificial fecundation of
my amphibious animals> for the abundance
of matter is ill adapted to the limits of a letter,
I will rather take the liberty of doing it,
when I fhall have fufficient leifure to extract
from my journals the fum of my obfervations.
In order to compofe a fupplement to my pub-
lication on that fubjedt.

' Meanwhile, I pafs on to the artificial fe-
cundation of quadrupeds, concerning which
I will obferve to you, that I feel the greateil
fatisfa<?:ion at finding that my fentiments do
not differ from thofe of your fovereign.
When I fucceeded in the artificial fecunda-
tion of a bitch, meditating with furprize

. upon my difcovery, I conceived that it might
be an excellent way to procure, if the thing
be poflible, different forts of ftrange monies, an
idea in which my illuftrious friend Mr. Bon-
net, to whom I ufually firft communicate my
experiments, concurred. Hence I refolved
to provide myfelf, at my convenience, with
a number .of female quadrupeds, as- cats,
bitches, rabbits, and to try to fecundate them
with the feed of fome different fpecies, at the
feafon of their amours. I like wife communi-
cated this idea, to Dr. Rofii, a celebrated Pro-
feilor in the Unlverfity of Pifa, that he might

put

476 APPENDIX.

put it in practice : Dr. Rofli, as you perhaps
know, is the naturalift, who laft year re-
peated, with fuccefs, my experiment on the
artificial fecundation of a bitch. Towards
the middle of laft November, when I returned
to the univerfity of Pavia, I procured two
cats, one two years old, which had once
brought young, the other eleven months old,
and which had never produced. Both had
the liberty of my chamber, but they could
not get out, nor was any mak ever permitted
to enter : there was only in the fame apart-
ment a little fpaniel three years and a half
old, the fame which had furnifhed the pro-
lific liquor that fecundated the bitch. Th«
older cat was firft in fcafon ; this fell out on
the 3d of December: inceflant loud cries,
fnfficiently expreffive of her wants, afforded
a clear proof, that fhe now began to feek and
to invite the male. Being unable to fatisfy
her defires by means of a male of her own
fpecies, and being by nature, like all other
female cats, exceedingly falacious, flie for the
prefent forgot her antipathy to the dog-kind,
and did not hefitate to approach the fpaniel,
and to invite him, by ftroaking his belly, and
reiterated carefles; but he, without either
hurting the cat or flying, never confented to
her wiihes^ though he was of a very volup-
tuous

A P Pi E N D I X. 477

tuous difpofition ; he would fmell her, and
then turn with indifference another way*
The third day after the appearance of thefe
ligns, I tried to fecundate my cat artificially
with twenty-two grains of feed, furnifhed by
the fame dog. The fame means and precau-
tions were employed as in the experiment on
the bitch. But having obferved that the fe-
males of this fpecies receive the male many
times, I was not fatisfied with a fijigle injec-
tion, but repeated it thrice more before the
cat went off her heat, which happened on the
lith of December^ I kept her confined
along with the other, as in a former expe- •
riment.

You may conceive my anxious expedlation
of the refult of this unattempted experiment.
Should any one of my injedlions prove pro-
lific, and fhould the young partake, both in
form and manners, of the female which con-
ceived them, and the male that furniflied the
feed, I fancied, that the moft Angular mules,
and fuch as had never been before feen,
would now be produced. With refpe(ft: to
juanners, two moft oppofite natures would
be kneaded together and be confounded ; the
one, that of an animal fufceptible of educa-
tion, full of courage, abilities, and fentiment,
all ardour, all affedion,. all obedience to bis

mafter,^

47S APPENDIX.

mailer; the other, that of an animal in in-
teriiai quaiities, far inferior, by inftindl in-
tradtable, abhorring all fubjedion, faithlefs
to its owner, affedionate only through in-
tereft, and born with an irreconcileable en-
mity to the former. Nor would the nature
of thefe two animals engrafted together, be
lefs different in a phyfical point of view,
whether we coniider the external configu-
ration, the proportion of the limbs, or the
internal organization. But unhappily this
was an occurrence not eafy to be brought
about by the experimenter, and in which his
labour is not crov/ned with fuccefs. The
cat, notwithlianding all my care, was not
fecundated. I was not, however, difcouraged
by this failure from repeating my attempt
with the feed of the fame dog and the fame
precautions, upon the other cat, which began
to be in heat on the 18th of January, and in-
ftead of four, I injedted feed feven times;
that is to fay, once every day as long as the
feafon of her amours lafted. At each injec-
tion i did not introduce lefs than eighteen
grains of feed; but im.pregnation did not
take place; for from the laft injedion to
the date of this letter, thirty-two days have
elapfed, and there does not appear the leaft
intumefcence of the cat's belly. This is

alfo

.APPENDIX. 4jg

alfo the cafe with the other, though the ex-
periment was made fo long before. We
know, that thefe animals brine: forth in
about 55 days, and bitches in fixty-three at
far theft.

I would not, notwithftanding, pronounce
the attempt impradicable, for I think that,
to warrant fuch an affertion, a greater num-
ber of trials is necefTary. Thefe two experi-
ments, however, may juftly render us mif--
truftful of any that ihall be hereafter attempt-
ed; I ihall not be furprized if they fhould
prove unfuccefsful, conlidering the widely
different nature of thefe animals . But fnould,
this really happen, we ought not to be dif-
contented, fmce Nature has thus replied to
our interrogatories 3 and her refponfes, what-
ever they may be, ihould be held precious by
us, as they ferve to increafe the ftores of use-
ful knowledge. Further, the failure of thefe
attempts, ought not to prevent us from making
others upon animals differing in their nature.
It is true, that every kind of feed will not
fecundate every fpecies of animal. This li^
quor, on which depends the perpetuity of the
fpecies, muft have a certain relation with the
embryos to be fecundated; and it is natural
to fuppofe, that fuch a relation does not be-,
long to all kinds of {Q^d. But it is alfo true,

that

4 So APPENDIX*

that we can only learn from the effefts, that
is from experiment, when this relation does
fubfift. The very experiments which at firft
feemed contrary to the production of fuch
and fuch mules, when repeated in a better
manner, proved favourable to it. BufFon
deftroyed our hopes of procuring mules, by
keeping rabbits and hares together, feeing
that in the experiment he adduces, the orie
fpecies never copulated with the other. But
this conjundlion has been effected by other
hands [a), and hence hare-rabbits have been
procured. A dog and a fhe-wolf, kept to-
gether for a long time by the fame author,
never jfliewed any fign of mutual attention.
But the experiment, when repeated by others,
had a very different degree of fjccefs. The
mules that were by thcfe means produced pro-
pagated their kind [b) : Buffon failed in the
fame manner with refpecfl to dogs and foxes :
this experiment has not, as far as I know,
been repeated by others. I fhould think,
that in more expert hands, it would have been
•attended v/ith a more fortunate refult. But
in the race of mules, there is nothing per-
haps fo curious and furprizing as the famous

(a) In thofe of the Abbe Amoretti.
{}) Bonnet CEuvres, T. 3.

Jumart.

APPENDIX. 481

Jumart. Three varieties, you know, are
enumerated, the offspring of the bull and
mare, the afs and cow, and the bull and ihe-
afs. Leger and Shaw admit the exiftence of
all without hefitation ; but Buffon, in his hif-
tory of animals, reckons them all imaginary.
Yet in his fupplement, he does not abfolutely
deny the poiTibility of their exiftence, though
he doubts it much. But in truth, the
French Pliny was miftaken. Mr. Bourge-
lat, formerly infpedlor-general of the Ecole
Veterinaire at Lyons, in a letter to the il-
luftrious Bonnet, exprefsly fays, that he had
been in poifeilion of feveral of thefe Jumarts,
and that one was diifecfted under his in-
fpedlion in the fchool at Lyons 5 and he com-
municates the refult in his letter to the phi-
lofopher of Geneva [d), .The authority of
this celebrated and ingenuous perfon, merits
the utmoft deference. AiTuming then the
exiftence of this iingular fort of mule, I
could wifh that they fhould be multiplied
much more than they have hitherto been,
both beca'ufe they are well adapted to throw
fuller light upon the great function of gene-
ration, and becaufe they may poffibly prove
highly advantageous to mankind, as they are

(«) I.e. V

Vol, II. li faid

482 APPENDIX.

faid to have been poffeffed of extraordinary
ftrenorth. Natural fecundation, tho' ftudi-
ouily attempted, would not very fully accom-
plifh this objeCl, on account of the indif-
itrence, or rather the averfion of quadrupeds
of various forts to copulate together, ef~
pecially w^hen they happen to be placed at a
ereat diftance from each other. Thefe il-
legitimate marriages take place only, when
the afs or the bull cannot find the means of
fatisfying their defires upon their own fpe-
cies, and are moreover uncommonly ardent.
Artificial fecundation, properly performed,
would be moll: convenient in this cafe. I
will add, moft refpe6table Marquis, that I
am well difpofed to put it in pradlice; but
my public and private engagements have
hitherto prevented me, as alfo the expence,
for I will openly acknowledge it, of keeping
thefe animals for feveral months, to which
the narrow income of a philofopher is not
very adequate. Hence I made application
to a rich perfon in Lombardy, to aflifi: me in
thefe experiments ; but he was infenfible to
the propofal, a circumflance which did not
fiirprize me, as it certainly will not furpri^e
you, v/ho knov/, that the nobility in many
cities of Italy are not very friendly to fcience
and literature. In order to fatisfymy wiflies,

I fee

appendix; 483

I fee no better expedient, you will excufe my
philofophical freedom, than that of apply-
ing to you. The high honour you enjoy, in
poffeffing a ftation in the court of one of the
greateft princes upon earth, fuitable to your
eminent virtues and valuable endowments,
of a prince, who is at once the delight of his
happy kingdom, and the great protedlor of
letters and learned men : your ardour for na-
tural philofophy, and for whatever has a ten-
dency to ennoble and advance it; your clofe
conned:ion with our famous royal academy of
fciences and polite literature at Berlin, which
is fo defirous of enlarging the limits of this
noble branch of knowledge, by the fure gui-
dance of accurate experiments: thefe favour-
able circumftances afford me hopes, that you
will not refufe to fecond my wifhes. I am
willing to believe, that you will choofe the
moft advantageous moment to fpeak to your
fovereign of this curious project; nor do I
defpair of his encouragement, fmce it may, in
fome fort, be termed a thought of his own.
But enough of this. I proceed to another
fubject.

[The remaining part of this letter^ having
m connexion with any topic treated in the fere ^
going DiJfertationSy is omitted,']

I i 2 S PA L-

4^4 A P P E N I>

Spallanzani having adverted. In more
Paffages than one, to the Fecundation
OF Fishes, Mr. Ferris was induced to
fend the following Observation to the
Editor of the "Journal de Phyfique.

AT the age of about fourteen or fifteeny
he happened to be on the bank of a
river abounding in fiflies. The ftream was
rapid, but the water was fo lliailow and clear,
that at about the depth of two feet, he ob-
ferved two falmons ftirring the fand with
their tails, which were turned to each other.
They made a hole in the ihape of a funnel,
over which the female placed the extremity
of her tail, and difcharged a quantity of red
liquor : her place was then immediately taken
by the male ; who, in the fame pofition, e-
mitted a conliderable jet of white liquor.
They then in concert covered the hole with
fand and parted.

. This obfervation is fucceeded by a paper,
copied from Mr. Duharners work on fifhes
and fiilieries, on the mode of producing fal-
mons and trouts, as it is prad:ifed on the
banks of the Wefer. It is not furprifmg that
an effay,- written chiefly with oeconomical

views.

APPENDIX. 485

Views, fliould not in every refped fatisfy the
curiofity of the philofopher. A box or cafe
of wood is directed to be made with an aper-
ture towards the bottom of two oppofite
fides. The aperture is to be fecured with a
grate of iron. The bottom is to be covered
with fand and gravel, and a gentle ftream is
to be brought through the box. In No-
vember, when the falmon repairs to brooks
and rivulets, in order to propagate the fpe-
cies, a female is to be held by the head over
a bucket of clean water. If the eggs be
quite mature, they will drop out of them.-
felves; or if they fhould not, gentle pref-
fure on the belly will bring them out. The
male is to be treated in the fame manner, and
w^hen the furface of the water appears white
with milt, the operation is finilhed. The eggs
are now to be carried to the box. Some-
times the young are formed in five v/eeks,
and may be {^cn to move in the egg. They
inay be diftinguiihed by their eyes, which
are black, while the other parts are yet dia-
phanous : in eight days afterwards they break
through the fkin or membrane of the egg.
This period, however, varies with the tem-
perature of the water, and of the atmofphere,
and is fometimes prolonged to ten weeks.
While the young fry is growing in the egg,

I i 3 a fine

485 APPEND

X.

a fine pellicle, diftinfl: from the external mem-
brane, may be obferved; to this pellicle the
little fifh is attached ; it forms a fac round it.
The fac fills almoft the whole capacity of the
egg, and ferves the fetus Jor a jlomach and
bowels. The firil feeds upon the matter con-
tained in it four or five weeks after it is hatch-
ed. During this time the mouth, which is
at firfl fhapelefs, gradually elongates ; after-
wards the fac totally difappears, and the ani-
mal affumes its perfect figure.

The fame method is to be obferved with
refped: to trouts, but their eggs are not ma-
ture till December and January.

The author obferves, that fiihes do not co-
pulate, and that fecundation is external. He
procured from a trout fome eggs perfectly ma-
ture, and took the utmofl care of them, but
he put no milt upon them, and they all fpoiled
without producing a fmgle young fifli.

Among the trouts produced according to
the method above-defcribed, there appeared
many varieties of monflers ; the author ex-
plains, thefe phasnomena from Lewenhoeck's
hypothefis concerning the fpermatic worms.

But the mofl curious experiment in this
paper is the following. The author took
the mature eggs out of a trout, which had
been dead four days, and which was now

very,

APPENDIX. -487

very putrid and offenfive. He covered them
with the milt of a Hving male, and the pro-
duce of fry was as abundant, as if the eggs
had been furniflied by a living female.

He next propofes to fecundate the eggs of
the trout with the milt of the falmon, and
reciprocally. He pretends, that certain wa-
ters, and a particular kind of food, will con-
vert trouts into falmon- trouts.

He afferts, that the eggs of both thefe
fpecies infallibly perifh, if any impurity ad^
heres to them, or if they lie long upon the
ground; hence he deduces the final caufe of
their depofiting their offspring upon the gra-
velly bottom of rivulets, in places where the
flream is continually freeing them from im-
purities*

AH

A N

ANALYTICAL INDEX

OF THE

CONTENTS

O F T H E

DISSERTATIONS.

INTRODUCTION.

/^N the pre-exiftence of genus, and the artificial fe-
^^ cundation of animals and plants - Pao^e i

DISSERTATION I.
C H A P. I.

GENERATION OF THE GREEN AQUATIC FROG,

I', Why Co called - - ^

II. Difference between the male and female • ib.

III. Eflential difference between t/iis fpecies, and that
called by Roefel by the fame name - 6

IV. Seafonof its amours. Ovarium and eggs defcribcd ib.

V. Miftake of Vallifneri - * y

VI. Eggs of frogs increafe in fize at the feafon of their
amours. Duration of copulation. They bring forth,
though confined - - 8

vii. Condition neceffary to parturition - 9

VIII. Diff'erent fituations of the eggs during copulation.
Great difference between the eggs in the ovarium and
in the ovidu61:s, as well as uierus • ib.

IX. Proofs that the eggs are not fecundated in the body
of the female. Miftake of Linnaeus - ib.

X. Miftake of Profefifor Menzius - lO

XI. XII. Mode in which fecundation is effe6led without
the body of the female « - it, 12

XIII. Cu-

INDEX.

xiii. Curious and inftru<Slive experiment to hinder the
fecundation of the eggs, propofed by NoUet, and fuc-
cefsfuUy performed by the author - 13

XIV. Defcription of the eggs at the time of parturition 14

XV, XVI, XVII. The globules, hitherto called eggs, are
not eggs but tadpoles. Succeilive evolution of
them - - 15, 16, 17

XVIII, XIX. proofs that the fetus of this fpecies exifts
before the acceffion of the male. Important confe-
quenc^s dedyced from this difcovery - 17-19

CHAP. ir.

GENERATION OF THE TREE-FROG,

XX. Defcription of this frog. Its habitation 20

yxi. The embrac&s of this are different from thofe of

other fp€cies of frog - - ib,

XXII. Difference of duration of copulation of this fpe-
cies in Italy and Germany - 21

XXIII. Roefel knew not the mode of fecundation in
this fpecies - - ib.

XXIV5 XXV. The author was more fortunate, He faw
the femenof the male irrotate the eggs 21, 22

XXVI. Fecundation external, yet fometimes takes place
internally - - 22

XXVII. Miflake of Roefel about the gluten of the eggs 23
xxviii, XXIX. Progrefs of evolution. Animation.

Difcoyery that what were thought to be eggs, are fe-
tufes - - 23, 24

XXX. They pre-exift in the female - 25

xxxi. The fetufes of this fpecies continue longer in
the amnion than thofe of the preceding - 26

xxxii, xxxiii, xxxiv, XXXV, XXXVI, xxxvn. Sum-
mary of Roefel's obfervations on the tree-frog. His
miflakes - - - 26, 27, 28

31XXVIII. Singular fhape of the tadpoles that perifh in

the amnion r. ' ' ^^

XXXIX. ?re«»

I N D ^ X.

XXXIX. Precaution neceflary to the growth of the
young - - - 29

CHAP. III.

GENERATION OF THE TOAD, DENOMINATED BY ROESEI,,
BUFO TEREESTRIS, D08.SO TUBERCULIS EXASPERAXO,
OCULIS RUBRIS.

XL. Two fpecies of this toad. No dliFerence between
them in what refpeils generation - 30

xLi. Seafon of their amours. Difference of fize be-
tween the male and female. The male adheres to the
female when fhe flies - ib.

XLii. The eggs adhere to the ovarium at the beginning
of copulation. Its duration. Salacioufnefs of the
males ~ *" 31

XLiii. Noife made by the male at this time * 32

XLiv. Inteftine motions in the female's body, while the
eggs are pafling through the oviducts and uterus ib.

XLV. Duration of the diicharge of the eggs in two
cords - - ib.

xLvi. Remarkable length of the cords. Number of
the eggs - . 33

XLVii. The males do not quit the females when they
are removed out of the water - ib.

XLViii. Poftuie of the male when fecundating the eggs 34.

XLix. The eggs are fecundated by the feed, which is
' •'■ brought gently into contact with them - ib.

L, The manner in which thefe very long cords are fe-
cundated - - - ib.

LI. Decifive proofs that the liquor with which the male
bedews the eggs, is the fecundating feed - ib.

Lii. Fecundation lakes place in thefe animals without
the female's body - 35

LIU. Whether the bodies hitherto called eggs are tad-
poles, and if fo, whether they exilt before fecundation ib.

LIV,

INDEX.

tiV, IV5 LVi, Lvii. Analyfis of thefe coipiifcles, with
direit proofs, that they are tadpoles not yet evolved,
and they are to be found in the females before the ac-
cef£on of the male - - -^q, -^6

Lviii. Pre-exrilence of the amnion before fecundation 36
Iix. The blood manifeftly circulates before there ap-
pears the leaft motion in the tadpole - ib.

C H A P. iV.

CENERATION OF THE FETID TERRESTRIAL TOAD,

LX. Specific difference between this animal, and that
called by Roefel, Bufo terrefhis foetidus 39

LXi. Refpefis, in which the male and female differ,
and in which they agree - - 40

Lxii. Stagnant waters are chofen by thefe animals for
the purpofe of propagation - ib.

Lxiii. Seafon of copulation - - ib,

LXiv. Great difference of the feafon of amours of this
fpecies, and that defcribed in Chap. III. The former
require a warm temperature - - 41

XXV. The duration of copulation in frogs and toads,
appears to be inverfely as the heat of the atmo-
fphere - - - 42

ixvi. The female does not discharge her eggs without
the embraces of the male - 43

txvii. Eggs fallen into the thorax and abdomen.
Way in which this may happen - 44

Lxviii, LXix. Duration of copulation. Manner in
which the eggs are fecundated - ib.45

Xxx. The eggs, when difcharged, are inclofed and im-
bedded in cords of gluten, which matter is generated
in the cavity of the eggs. The eggs do not grow
when ftripped of the gluten or amnion - 46

xxxi. in this fpecies alfo the round bodies^ hitherto
called eggs, are tadpoles - 47

Lxxii, They pre exift in the female - ib.

txxiii. As alfo does the amnion, and probably the
umbilical cord - - 4^

LxxiV. Pie-

INDEX.

Lxxiv. Precautions for the life of thofe who fiiall de-
fire to repeat thefe experiments - 4Ji

XXXV, Lxxvi. Dried eggs of Hilies lofe the power of

producing, wiiich alfo happen'* ro tadpoles in the form

^of eggs. Confequence^ refpecting th'^ exp' cation qivea

by fome authors, of the appearance of fiOies in places

where they no longer exilted - " 50*52

CHAP. V.

GENERATION OF THE WATER-WBWT OR SALAMANDER,

Lxxvii. Marks of tke two fpecies examined by the
author " ~ " 54

Lxxviii. Their places of abode - 55

Lxxix. Remarkable, phasnomenon obferved by the au-
thor, with refpe(Sl to newts in fpring, and in autumn ib.

Lxxx. Singular manner in which the male impreg;nates
the female without copulation - 57

Lxxxi. Confirmation of this obfervatlon. Inftanta-
neous eonjun£tion of wall-iizards - ^g

Lxxxii. Agreement of the author's obfervations witiv
thofe of a French Naturalift - 6r

Lxxxiir. Eggs, ovarium, and ovidu^ls described 63

JLXXXiv. Eggs get into the du6xs at the feafon of a-
mours. Thofe only are fecundated which are upon
the point of being discharged - 64

ixxxv. Although the more are fecundated afterwards.
Duration of the amours of newts - 66

Lxxxvi. Miftakes of Bomare - 67

J.XXXV11. Gradual evolution of the eggs, which fliews
that they are only newts in miniature - 69

ixxxviii. The young newts, as they are further
evolved, not being capable of being contained in the
amnion, burft it - - y2

Lxxxix. Time requifite for thefe animals to pafs from
the fallacious form of eggs, to the true one of newts.
Great difficulty in hatching them - 72

xc. Afterwards reared more eafily. Evolution of the
hands and feet. Duration of the gills. 74

xci. Pre-

N D E X.

xcr. Pc(p-exlftence of the fetus - ^6

xcii. Generation of another fpecies - 77

c H A P. vr.

REFLECTIONS,

xciii. Seafon appointed for the generation of quadru-
peds and birds. In infecSls the feafon varies according
to the warmth or coldnefs of the weather - 79

xciv. As alfo in the amphibia above-mentioned. They
copulate fooner in warm than in cold climates 80

xcv. They are to be removed from among oviparous
to viviparous animals. They have a diftinguifhing
charafteriftic j for which it does not feem difficult to
account - - , 82

xcv I. They appear to have the fame forefight as other
animals, for the multiplication of the fpecies - 85

xcvii. The end for which the male fo clofely embraces
the female. Difcuffion of the opinions of two Natu-
ralifts - - - ^ 87

xcviii. Caufe of the perfeverance of the male in em-
bracing the female fo long, and of their neglecting
their owr? fecurity - 90

xcix, c. Piinitures, incifion, cutting off the limbs, de-
capitation, do not prevent the male from adhering to
the female, and fecundating the embryos 92-94

cr. An highly improbable opinion of Swammerdam 96

cii. Curious obfervation of Demours. Reflections 97

cm. The manner of fecundation in thefe amphibia, de-
ftroysa law hitherto fuppofed to be univerfal 99

CIV. Mode of fecundation in other fpecies of the fame
genera unknown, and fhould be inveftigated. The
Fipa of Surinam deferves particular attention. Sketch
of Mr. Bonnet's and the author's experiments on this
fpecies > • ib.

cv, cvi. Doubts relating to the generation of fiflies.
Kidiculous opinion of Linnseus. A mode propofed of
inveftigating themyftery - 104,105

cvii. Fecundation of bee's eggs external. Number of
animals in which this takes place, very fmall in com-*
parifon with thofe in which it is otherwife 107

cviii. Re-

INDEX.

cvni. Rcflc(!lions upon the fingular fecundation of
newts - - - loS

cjx. The author's difcovery of the pre-exiftence of the
fetufes in thcfe amphibia, totally overturns the fyftefn
of Epigenefis ; as alfo that of the Vcrmicul'ijh, Every
reafon to fuppofe that the fucceflive orders of fetufes,
which every year become conspicuous in the ovaria,
have co-exifted with the female - iir

ex. Examination and confutation of a fingular opinion
concerning the generation of frogs - 114

CHAP. Vll.

EXAMINATION OF SOME RECENT OBJECTIONS MADS
AGAINST THE SYSTEM OF THE P RE-EXISTEN C £ OF TKR
GERM IN THE FEMALE,

cxii. Dr. Pirri's obje£lIons to the author's difcovery,
with replies - - 119

cxii. Reply to two objections made by Dr. Pirri 125
cxiii, cxiv. Identity of the tadpole and frog 126-129
cxv. Objection of Dr. Pirri againfl Haller 132

cxvi, cxvii. Extract of a letter of Mr. Bonnet 136^ 137

DISSERTATION II.
C H A P. I.

ARTIFICIAL FECUNDATION OF THETERRESTRIALFROG,
WITH RED EYES AND DORSAL TUBERCLES.

exviii. Vain attempt of Malpighi and others, to fe-
cundate the filk-worm. The author's defign to make
the experiment on frogs and toads - 1 42.

cxix. He fucceeds on the prefent fpecies - 144

cxx. A greater quantity of tadpoles produced by a
greater quantity of feed - - - i^y

cxxi. The experiment fucceeds alike, whether the tad-
poles be wetted with feed before or after they are im-
merfed in water. Artificial fecundation equally cal-
culated to animate the tadpoles with the natural 148

cxxii. Thc^

I N r> E Dt,

cxxti. They may be fecundated while yet in the ute*
ruSi Abience of the fpermatic worms from the feed,
not at all unfavourable to fecundation - 149

cxxiii, cxxiv. Artificial fecundation cannot be ef-
fected at the upper part of the oviducts. The rea-
fon, nor does it fucceed on thofe that have acciden-
tally fallen into the abdomen, and thofe that are net

- yet feparated from the ovarium - 151*153

cxxv. Juice exprelTed from the tefticles, juft as fit for
fecundation as feed - - 154

cxxvi. New fpecies of toad. Artificial fecundation
fucceeds in this, as well as the former - 156

cxxvii. The fame law is obferved by Nature in the
generation of this fpecies, as in the other amphibia be-
fore defcribed « ^ - i^S

CHAP. ir.

ARTIFICIAL FECUNDATION OF THE WATER-NEWT,
AND FETID TERRESTRIAL TOAD.

cxxviii. Artificial fecundation unfuccefsfully attempted
in the witer-newt, with pure feed - 161

cxxix. Obtained in fome meafure by feed mixed with
water. Juice of the tefticles equally efficacious, if
mixed with water - - 163

cxxx. In the fetid toad we may obtain the various forts
of fecundation mentioned in paragraph cxix, cxx,
cxxi, cxxii, CXXIII. Seed of this toad fit for
fecundation, after it has continued in the veficles of
the animal feveral hours after death - 165

cxxxi. As' alfo after landing in a vefiel. The time
at which it iofes it, depends on the temperature of the
air. Phyfical caule of the inennefs of the feed 168

cxxxii. Juice of the tefticles keeps its virtue longer
than feed - - 170

cxxxiii. The tefticles, when fhrunk, are not deflitute
of this virtue , but they are, when dried, as alfo when
expofed to a ftrong hear. Tefticles of toads kept by
themfelves, >uid of thofe which are too young, are un-
fit for fecundation " - J 71

cxxxiv. Seed

INDEX.

cxxxiv. Seed and juice of the tefticles does not lofe
their prolific power when incorporated with other li-
quors - - - jy^

cxxxv. Tadpoles preferve the power of being fecun-
dated and evolved, after continuing for a certain time
in the dead uterus - - 1-5

cjycxvi. A few minutes immerfion in water, render
tadpoles incapable of being fecundated. Phyfical caufe
of this - . - 1-78

cxxxvii. The male bedews with feed only thofe tad-
poles which havejuft fallen into the water. Fecunda-
tion in frogs and toads very different from that of
fiihes, according to the common opinion - 1 80

CHAP. III.

ARTIFICIAL FfCUN'DATION OF THE TREE-FROG, AND
THE GREEN AQUATIC FROG.

cxxxviii. The fmall number of tree-frogs In the au-
thor's poiTeflion, confined him to a fQw experiments.
Defcription of the genitals of the male of the green
aquatic frog - - 182

cxxxix. Very little difference In the refults relatircr
to the green frog, from thofe defcribed in the two pre-
ceding chapters - - •^03

CXL. Fecundation is effected by touching any point of
the mucous fpherules furrounding the tadpoles. A veiy
fmall particle of feed fufHcient - 184

-cxLi, And that though it fliould have to pafs througK
a thick ftratum of gluten - I'Sy

CXLii. Three grains of feed, mixed with a pound of
water, retain their virtue - 189

cxLiii. And even with a pound and half, more water
is prejudicial ; but in twenty- two pounds it preferves
fome portion of its virtue - 19I

CXLIV. Other facls proving yet more directly, that an
inexpreiTibly fmall quantity of feed is fulficient for fe-
cundation - - 192

CXLV. Three grains of feed, mixed with a confiderabie

quantity of water, does not become effete, after hav-

VoL.II. iLk ins

INDEX,

lag fecundated a prodigious multitude of tadpoles. Fe-
cundation takes place alike, whether they be kept im-
merfed for a long time, or a few moments ; only this
mixture continues prolific for a number of hours, efpe*
cially in cold weather - - 192

cxLvi. Juice of the tefticles of equal efRcacy in all
refpe6ts - - - 194.

cxLVir. The two fpecies of toad defcribed in the two
preceding chapters, afford the fame refult in experi-
ments of this kind, as the green aquatic frog. Ufeful
precautions - - - 195

cxLViii. Tadpoles and newts artificially fecundated, dif-
fer in no refpedl from thofe fecundated by nature igB

CHAP. IV,

R E F L E C T J 0 N &.

CXLIX. Artificial fecundation v»^ith feed without wontis,
is a new and decifive proof that they are not the au-
thors of generation - - 2C0

CL. Subterfuges in defence of this theory,\incompatible
with the experiments related - 203

CLi. Thefe obfervations alfo demonftrate the falfehood
of Epigenefis ^ ■ - - - 204

CLii. The feed muft penetrate into the body of the tad-
poles. Pores for its admiilion. Why the tadpoles are
animated, whatever part be touched - 205

CLiii. The animation of the tadpole is according to alf
appearance occafioned by the irritation of the heart,
from the impulfe of the Jeed - 208

CLiVo Properties of the ieed of frogs and toads, which
do not preveit its flimulating the heart - 21a

CLV. Quantity of feed fufHeieat to fecundate a tadpole^
expreffed in numbers - - 211

CLvr. UluHration by examples - - 214

CX.VII. 7'he quantity, when leflened, is incapable of ef-
fecting fecundation. Reafon to believe that the quan-
tity v/hich produces fecundation, is always exceedingly
fmall - - 215

cLViii. Whe-

1 N I) 5 x:

Gtviti. Whether this holds in other animals. We havs
not data fufficient to folve the qudtion with certainty,
how to procure them - 217

CLix. The feed of frogs and toads is probably not a nu-
tritious liquor, it is a true ftimulus - 220

CLX. Whether the feed of other animals alfo retains its
qualities for fome time - - 224

CHAP. V.

WHETHER FECUNDATION IS AN EFFECT OF THE AURA
SEMINALIS. WHETHEa OTHER LlQ^OR3 ARE CAPABLE
OF PRODUCING FECUNDATION. TRIALS TO PROCURE
ARTIFICIAL MULES IN THE AMPKIBIOUS ANIMALS iH
QUESTION, ARTIFICIAL FECUNDATION OF THE SILK-
WORM. ATTEMPT TO IMPREGNATE A BITCH ARTI-
FICIALLY.

\

tlxi. It is yet doubtful whether fecundation is produced
by the aura fpermatica^ or the grofs part of the kic:d 226

CLxii. Tadpoles immerfed in the aura fpermatica alone,
and yet not animated - - 228

CLxiii, CLxiv, CLxv. Clear confirmation of this, and
conclufion that the grofs and vifible part only of the
feed is capable of fecundating tadpoles 230, 231, 232

CLxvi. This is alfo true of the juice of the tefticles.
In other animals, and in man, the aura feminaiis is pro-
bably inefficacious - - 233

CLXVii. The part of the feed that occafions fecunda-
tion, is not a fpirituous or very volatile liquor, as many
have fuppofed - - 234

CLXViii. ElciSlrical fluid accelerates the growth of fe-
cundated tadpole^;, but is incapable of animating un«
impregnated ones - - - _ 235

CLXix, CLxx. Nor any other liquors different frora
feed - .- 238-24.0

CLXXi. Seed of the water-newt incapable of fecundating
the embryos of frogs and toads, and reciprocally. Nor
can the feed of frogs fecundate the young of toads, and
reciprocally. Toads never copulate with frogs 241

CLxxii. Eggs of the moths produced by the filk-worm,
grtihcially fecundated - r " ^4^

CLxxai. Ai-

INDEX.

CLxxiir. Artificial fecundation of a bitch - 248

CLxxiv. Small quantity of feed fuiHcient for the pur-

pofe. Highly probable that the quantity of feed which

occafions fecundation in other animals, is exceedingly

minute - * ^51

Two letters from Mr. Bonnet - 253

DISSERTATION TIL
CHAP. I.

GENERATION OF THE PLANTS DENOMINATED BY LtK»
N^US, SPARTIUM JUNCEUM, VICIA FABA, PISUM SA-
TIVUM, DOLIGHOS UNGUICULATUS,

I. The ovarium of plants, chofen by the author as the
principal obje^i: of his refearches, and propofed to be
examined at three periods - - 31^

II. Seeds of the fpartium junceum exift long before fe-
cundation, though the plantule and lobes do not ap-
pear - - - 315

III. Neither do they appear in feeds about to be fecun-
dated, or at the time they are fecundated - 317

IV. A cavity begins to form in the feeds, fome time af-
ter the falling of tl>^ flowers, and in this appears a lit-
tle body, at firil iliapelefs, but afterwards known to be
the piantule and lobes. Attachment of this body to
the feeds, Furthe,r evolution of them, the plantule
and lobes » - - 319

V. Confequenc^s from thefe experiments,, which fhew
that the integuments of the feeds appear before^ fecun-

;dat!on, but the plantule lobes not till afterwards 321

VI. The feeds alfo of beans exift in the ovarium before
fecundation. Cavity is formed afterwards. Appear-

\ance and evolution of the plantule and lobes, mucilagi-
nous iiiament v/hich connects the feeds and planiule ib,
Yii. The fame phasnomena obferved in peafe and kidney
beans " - " 3^3

CHAP.

INDEX.

C H A P. ir.

GENERATION' OF THE PLANTS DENOMINATED BY LIK-
HJEVSt RAPHANUS SATIVUS, CICER ARIETINUM, IXIA
CHINBNSIS, DELPHINIUM CONSOLIDA, CUCURBITA
PCPO, CUCUMIS SATIVUS. EXAMINATION OF THE

POWDER OF THE STAMINA.

vni, IX. Radifh and chick pcafe agree with the fore-
going plants. More points of conne6tion between
the feeds and plantule - 326, 327

X'. Exiftence of the feeds of the Ixia Cbinenjis before fe-
cundation. A cavity begins to form in the feeds about
the time of fecundation, full of a liquor which is gra-
dually infpiflated, and at length becomes hard, without
{hewing any appearance of plantule and lobes. The
enquiry left unfinifhed, for v/ant of ripe feeds 328

XI. Appearances nearly refembling thofe of the Ixia
Chinenfis^ in the Delphinium confolida^ with this phas-
nomena befides, that the plantule and lobes are dif-
cerned in the condenfed liquor of the feeds. Strong
fufpicion that this is the cafe in the Ixia^ as is after-
wards verified in ripe feeds - 329

XII. Seeds of the common pumpion appear in the fruit
long before the female blofToms are expanded, Ana-
lyfis of thefe feeds, whence it might be fuppofed that
the plautale and lobes appear before fecundation. Ana-
lyfis of feeds further advanced ; whence it appears, that
the lobes and plantule are not vifible In a month after
the v/itheiing of the flowers. Mucilaginous, and ap«
parently organized body, inferted by one end into the
apex o/the feed, and by the other into the plantule 330

XIII. The fame phaenomena in the feeds of the cucum-
ber. All the other plants, which the author had an^
opportunity af examining, alfofhew that the feeds ap-
pear before fecundation, and the lobes and plantule af-^
tervvards. Thefe refuks correfpond with DuharaeFs
obfervation. Reafons for fuppofing this to be a law of
Nature - - - 334

XIV. The non-appearance of the plantule in feeds be-
fore fecundation, feems a plaufibie argument, that the
plantule pafTes from the pollen to the feed. Motives
for diihufting this arg^ument • 335

XV. Upwn

I N D E X*

5CV. Upon examining the component parts of the fe-»
cundating dud, there feems no reafon to think, that
the embryos are concealed within. Means imagined
by the author to remove all doubt * - 337

CHAP. III.

GENERATION CF SOM?) HE R M AP?1 R ODITE AND MONOI-
COUS PLANTS, ON WHICH THE POLLEN NEVER ACTED.

svi, XVII. Lopping off the anthers, when the blofibms
of fv/eet bafil are ahout to open, and preventing the
accefs of the pollen of other individuals, do not hin-
der an individual from producing the fame kind of
feeds as are produced by others, not deprived of their
antherae - - 342, 343

jcviti. Reafons for fufpe£ling, that the pollen a£ls as a
fecundating principle fome time before the opening of
the Rowers. Verification of this fufpicion 345

^ix. The total want of pollen piroduces the fame effedls
upon the feeds of the Hibifcus Syriacus, It is not,
therefore, the pollen which conveys the embryos into
the feeds^ of thefe two plants - - 346

XX, XXI. Seeds of the pumpion, with fhield-form fruit,
independently of the a(3:ion of the pollen, produce
a plantule and lobes ; and, when fown, other fertile
feeds - - - - 348-35<>

3CXII. As alfo happens in the feeds of the citron-pumpkin,
though the accefs of the external air was prevented 3^0

CHAP- IV.

GENERATION OF CERTAIN PLANTS PRODUCING MALg
AND FEMALE INDIVIDUALS, ON WHICH THE FECUNDA-
TI-NG DUST V/AS PREVENTED FROM EXERTING ITS IN-
FLUENCE,

^xiii. Sufplcions that the pollen of male hemp plants is
notueceilarytothefecundauon of female individuals 358

xxjv, Qthef

I N D E X.

XXIV. Other fufpicions ftill ftronger - 2^()

XXV. Experiments of a French anonymous writer 361

XXVI. XXVII, XXVIII. Experiments on confined female
plants of hemp - - 3^3*3^8-371

XXIX. Perfect fru6lification of hemp, entirely indepen-
dent of the action of the pollen - 373

XXX. Infulated female fpinaches produce fertile feeds 375

XXXI. XXXII. Experiments to the fame tendency 376, 377

XXXIII. Experiments of diiFerent tendency with female
plants of mercury - - 379

XXXIV. Approximation of the male individuals tends
to fecundate the feeds - - 3^1

xxxv, A nearer approximation produces more fertile

feeds - _ - 282

xxxvi, Experiment inverted - - ib.

CHAP. V.

RECAPITULATION, REFLECTIONS.

XXXVII. The confequences of thefe fa^ls are, hrfl, that
the embryo does not at all depend for its exiftence up-
on the powder of the ftamina ; therefore, feccndly,
the embryo exiftsin the ovarium independently of this
powder; thirdly, nor is it the refultof two principles,
one depending on the pollen, and the other upon the
piiVil, as others fuppofe - - 385

xxxviir. Whether the embryo is formed mechanically'
in the ovarium, or pre-exifls there. Reply to fome
ieemins; proofs of fuch a formation ; direct proofs
that though the embryo does not appear, it really
exifts ; and when its organization cannot be feen, it
is really organized - - • 388

xxxix. As the embryo is in mofl cafes vifibly attached
to the feeds, there- is reafon to fuppofe, thauit always
is, though the connecting media are either too fmall,
or too tranfparent to be vifible. As the embryo and
lobes thus form one wjiole witii the fe^s, and as the

fe^ds

index;

feeds exift before fecundation, it is highly probable that
the embryo pre-exifts likewife - -7^2

XL. The fame confequence deduced by Mr. Bonnet from.
a fimilar obfervation. We cannot, notwirhftanding^
hope to difcern the embryo before the opening of the
blolToms - - - OQC

XL I. This pre-exiffence, which has been (hewn in fome
plants, probably takes place in all - 398

XLii. The phaenomcna of bafil, and cfpecially thofe of
mercury, prove the neceility of pollen to the fecunda-
tion of thefe plants. A phasnomenon of the fame kind
obferved formerly on a female turpentine-tree 399

'XLiii. A palm artificially fecundated by Mr. Gleditfcho
The author's widi, that experiments of the fame fort
were made on mercury : and that that part of the pollen,
which occafions fecundation, ihould be determined 401

XL IV. And that Mr. Adanfon's opinion, that the moft
minute particle of dull is fuificient for fecundation,
iliould be brought to the teft of experiment 404

3SLV. And that it fhould be tried upon mercury whether,
as in Mr. Gleditfch's experiment, dry pollen will an-
fwer the purpofe, and how long it retains its virtue.
Reafons for fuppofing that this virtue does not laft
long, efpecialiy where the pollen is expofed to the in-
juries of the atmofphere - - 405

XLvi. And to inquire, how the pollen paffes into the
ovarium ; and, at the fame time, to try the validity of
an hypothefis of Mr. Adanfon, and likewife to deter-
iTiine, whether the piilils of mercury, and fome other
plants, are imperforated, as he pretends - 408

XLvii. The non-appearance of du6b in certain plants,
is not a clear proof of their non exiftence. How they
may be feen at fome feafons, and not at others. Inftan-
ces in the ovidu(?-S of certain animals. At what feafon
they iliould be fought for - - 411

XLviii. To attempt artificial fecundation on the leaves
and roots, &;c. of mercury - - 414

XLix. If mercury and bafil require pollen for their fe-
cundation, the two fpeciesof pumpion, hemp, and fpi-
nach, are contrary inftances. The fraaJlnefs and
paucity of fertile feeds of hemp, procured in a clofe
apartment^ do not depend on the abfence of pollen.

General

INDEX.

General confequence, that if many plants require tlie
action of pollen for fecundation, others do not 415

L, LI, Lii, Liii, Reply to objedions that may be ftarted.
Defective mode of reafoning, hitherto employed to
maintain the diftin<5tion of fexes 418, 419-422-424.

Liv, This defedt common among fyftematic writers.
Different ways in which an adherent of fyftem, and
an obferver, examine Nature - 425

IV. Some plants requiring pollen, and others not, is
perfe6lly conformable to what we every day obferve in
animals - - . 427

Lvi. Highly Improbable, that the fertile feeds obtained
by the author, fliould be the produ6t of antecedent fe-
cundation. Confiderations in proof of this 428

XVII. Though it is proved, that the pollen does not ef-
{^tt the fecundation of the above-mentioned plants,
the author does not altogether deny the poffibility of
fome fort of fecundation; perhaps the piftil has a
fecundating principle. Reafons for this conjedture.
Exhortation to botanifls - - 4^1

Lviii. Herbaceous plants are a clafs of organized beings,
which deferve to be better known to Naturalifts, for lit-
tle more is known of them, than the bare nomenclature.
How much a fpirit of obfervation and experiment is to
be preferred to the knack of nomenclature, if we wifh
to increafe the ftores of ufeful knowledge - 433

APPENDIX.

Remarks on the abridgment of Mr. Demour's Obferva-
tion de deux animaux, dont le male accouche le fe-
melle - - 441

Debrav/s difcoveries on the fex of bees - 454

Part of a letter from the Abbe SpallanzanI to the Marquis
Lucchefmi - - 472

Obfervation on the fecundation of fiihes - ■ 484

TRANS.

TRANSLATION

OF THE

LATIN, FRENCH, and ITALIAN
Passages in this Volume.

Pa2;e lo. Neither fecundation or impreg;nation of the
■^gg^ takes place in any living body in Nature without
the body of the female.

Page 50. yf II things were created good,

Pafjc 1 14. The male frog, firmly feated on the female,
waits for difcharge of the eggs; he then emits his em-
bryos, fuch as I obferved them , they attach themfelves
to the Q^^.5^j and h^A upon them for a few day?, till they
are capable of taking coarfer food. Xhefe embryos re-
tain the figure which they had in the veficle of the male
for about a month j they then change their fbape like filk-
worms. Their hind fttt are next developed and fepa-
rated ; the hind feet vs^ere at firft united, and formed the
tail of the tadpole.

Page i!^. 1. 14. He advances ss ferious trutiis, tales
equally ridiculous with thofe told by old women, as they
fpin by the iire-fide

lb, I. 24- I will therefore venture to afTert, not onlf
that Gautier bad made little proliciency in the anatomy
of the frog^ but that he was fcarce acquainted with the
external form of this animal.

Page 118. 1. 4. Were it poilible that Gautier fhould re-
late his difcoveries to Pythagoras, I firmly believe, that he
would enjoin him fiience, not for two jor for five years,
but for ever.

Page 126. As often as the female difcharges any eggs,
the male bedews them with feed, as I have repeatedly ob-
ferved at my houfe, with fome admiration.

-P^S^ ^33* ^ refign this Dr. Pirri to you. He is in
good hands, and you will be fufHciently able to defend
the go®d caufe of Nature. It Is always a mark of te-
Eijerity to attack experiments by jcafoaii ng.

Pag€

TRANSLATION, 8cc.

Page 134. Laftly, we have a demonftration, which
directly proves the exiftcncc of the young in the female,
at leaft in birds. For the inteftine of the young bird is a
continuation of the membrane of the yolk, and the in-
ternal coat of the inteftine Is a continuation of the epi-
dermis, the external of the fkin : in fhort, it is the fame
as the membrane of the yolk.

Page 252. Nature, when I have been contemplating
her, has often perfuaded me to fuppofe nothing incredible
which relates to her.

Page 420. Should the hemp, producing male flowers,
be pulled before the feminiferous individuals have opened
their piftilifcrous flowers, there will either he no crop of
feeds, or only a very fmall one.

Page 426. We diftinguifh the obferver from the ad-
herent of fyftem. Tne lacter builds whole fyltems upoa
a certain number of fpecies : he concludes' from parti-
culars to generals, that is, he afligns to all plants the
fame properties as are poflTelled by thofe upon which
experiments have been made. The obferver rejects all
theories, and relies on obfervation and experiment alone.
The perfection of botany efl^entially depends on the know-
ledge of individuals related to each other, and their cha-
racleriftics. This knowledge will be acquired in pro-
portion as the numbers of obfervers, which is very in-
con fiderable, fhall increafe, and the croud of fyftem-
makers fhall be leflened. Syftems of botany become
obfolete in time, becaufe they are not chiefly founded oa
Nature and experiment.

Page 436. He was of opinion, that Natural Hiftorv
does not confiil: in a catalogue of animals, plants, and
foflils, but in the knowledge of their qualities. He
therefore taught their ftruiture, analyfis, properties an4
ufe, without neglecting, however, fuch marks as may
enable us to arrange them in an index. Thofe v/ho com-
mit to memory nothing but fuch indexes, or are dexte-
rous in turning them over, in vain perfuade themfelves,
that they are in polTeiuon of the book of Nature.

ERRATA;

In a PalTagf, tv'iich the Tranilator c^nKct nov\'- find, for mfreptated^ rea^
nnmprtvv.aud. The Coiitext wiii eafily cr'.abie the Rea(!,er to make this Cor—
recStion in the p?cpey Place >

TlieT'C- are aifo a few Iraproprieties iJi the Pun(Sufc'deK> whjck the Ra^d«s
1 s alio sisfired to corre^*

^

AfWH ,'Jm,■.'i;'S4Jvl^\lmm■ N-3tB„f/?rrrf_

J\M/?u/ /'Jeru^lje^i. lyJJ^^umiv A^.jtB^f/Mr/.

Pa^.^-

FigXVI

XVII

XX

J'r//'y&/i1/aK'i.^l4.(rIJf:uni'J"d2j!f<r^/6if,r/

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