The. Eats PL OrR 
fhort explanation, in which he juft takes notice 
of their difappearing in time; but this circum- 
fiance might be eafily known, and without the 
help of diflection, and I took notice of it myfelf 
more than twelve years ago. The gills hereto- 
fore defcribed, may be likewife feen within in the 
Frog’s mouth, through which the water flows 
upon them, and is then difcharged, after aiter- 
ing the blood that pafles through thefe organs. 
Nor could I ever yet difcover, that thefe bran- 
chie or gills, have any openings on the fides of 
the body, as is ufually the cafe in fifhes. 
Here it may be probably afked, whether the 
blood circulates in the young Frog, both through 
the gills and lungs? This I cannot abfolutely de- 
termine; for whilft I was engaged in thefe ob- 
fervations, I was difturbed with the cafes of 
many who were dangeroufly fick, which pre- 
vented my having time and leifure for examining 
this matter in the largeft young Frogs, one of 
which I have reprefented, Tab. XLVI. under 
No. V. otherwife I had refolved to render thefe 
obfervationson the generation and change of young 
Frogs as completeas poffible. I muft therefore de- 
fire the reader to accept what I now exhibit on 
this fubjeét, as the prelude only of a more per- 
fect work, to be hereafter publifhed. Though 
I have already obferved many things concerning 
this matter, I have not fuch confidence in my 
‘memory, as to prefume to publifh, before I re- 
examine them. | 
In order to make fome anfwer from my for- 
mer obtervations to the queftion I have juft now 
propofed, I am thoroughly perfwaded, that the 
greateft part of the blood circulates in the young 
Frog through the gills; and that only a {mall 
part of it is conveyed through the lungs; and 
this defigned probably only to nourifh them, and 
to fupply the remaining mafs of blood with air. 
The reafon why I propofe this opinion is, that 
only a very fmall portion of the blood circulates 
thus in full grown Frogs, in which the gills, be- 
ing probably thrown off with the laft fin which 
the Tadpole cafts, wholly difappear; and, on 
the other hand, the greateft part is after this dif- 
tributed into the whole body, out of the heart 
through the arteries, without touching the lungs, 
This is made evident in a letter, which I formerly 
wrote to the celebrated Oldenburg, fecretary to 
the royal fociety of London, and which is to be 
found in the philofophical tranfactions of that fo- 
ciety. I hope alfo, that by this obfervation, I 
have at length proved it, againft the opinion of the 
famous Malpighius and Needham, who think 
the blood is perfected in the lungs; that fan- 
guification, or the making of blood, muft be 
wholly attributed to the liver. I am perfuaded, 
that I can demonftrate it very eafily: though 
fome, ftimulated with envy and vain glory, bark 
againft it, like dogs again{t the glittering bright- 
nefs of the moon. My experiments concerning 
this matter, indeed, penetrate further than any 
perfon hath ever probably thought. But I return 
tothe Tadpole or young Frog. 
The heart, Tab. XLIX. Fig. 1. g, is placed 
between the gills in the Tadpole; and out of it, 
one may very diftinétly fee produced the great 
of. bwNe SB eC 4s., 
artery: this is divided into two branches; and 
thefe are further divided into very confpicuous 
{prigs or {hoots, which have all gills annexed to 
them: but whether fome of thofe branches are 
likewife tran{fmitted to the lungs, as is the cafe 
in full grown Frogs, 1 could not at this time, 
for the reafons beforementioned, examine: I am 
ftill doubtful alfo, whether all thefe thoots are 
diftributed to the gills alone. 
Near the heart is placed the auricula , which 
has not yet fuch a fituation or figure, as it has in 
full grown Frogs. But in the examination of 
the auricula, and its vefiels, ] have not yet ar- 
rived fo far as to fatisfy myfelf: therefore, I 
cannot exaCily declare, whether thofe two veins, 
which [ delineate under the Auricula, reach to 
the gills, and carry back the blood from them 
to the heart, or whether they communicate with 
the veflels of the lungs. All thefe matters fill 
remain to be inquired into. But for this reafon, 
I do not fcruple to delineate thofe parts, as they 
appeared tome, without examining them more 
exactly. 
Below thofe two veins is fituated the vena 
cava and liver,z; this I obferved to be divided, as 
it were, into four lobes: it is at this period 
whitifh, and fomewhat redifh. It is plainly 
difcovered, that the liver is compofed of very re- 
gular glandulons granules, which one may take 
for very fmall glands. Near the liver in the 
Tadpole is placed the gullet, 2, which defcends 
from the mouth to the fiomach, and is deline- 
ated here in that form. ut, in order to avoid 
confufion, I delineate the gall-bladder, 2, near 
the other fide of the gullet, That little bag of 
gall was at this time of a white, diaphanous hue: 
nay, the bile itfelf was limpid and perfpicuous, 
and without any bitternefs; though in the full 
grown Frogs, it is fometimes fo green and fluid, 
that it may be ufed to draw lines. The fluidity 
of the gall feems to me to depend on its piercing 
bitternefs, which is manifeft fome months after- 
wards, if paper, rabed over with fuch gall, be put 
into the mouth, The fpleen in the Tadpole is very 
{mall, triangular, but fomewhat irregular, and 
much more red than the liver: this is likewife 
the cafe in full grown Frogs. 
There was nothing more beautiful to obferve 
in this diflection, than the courfe of the gullet, 
ftomach and inteftines ; for thefe parts were ob- 
ferved to be very admirably convoluted in the 
body of the Tadpole. The firft Ginus, into which 
the gullet. was twifled, was about the liver, Tab, 
XLIX. Fig. 1. #, under which I have delineat- 
ed, 2, acertain portion of the mefentery, toge- 
ther with its blood veffels. The ftomach was 
in the beginning, and in its ftate of accretion, 
like a piece of red fleth, which being partly fitu- 
ated over the gullet and fmall guts, began o to 
{well and grow thick. But there was likewife 
obferved a great number of blood veflels, which 
diftributing themfelves through the ftomach, 
formed as it were a beautiful net. 
I here difcovered moft clearly, that the fto- 
mach in the beginning of the young Frog’s ace 
cretion, did not yet perform its office, which was 
in the mean time performed by its gullet and 
Gie inteftines 
117 
