FRO 
The tranfparent liquor nourifhes the tadpole, and 
anfwers the fame purpofcs that the whites of eggs 
do to birds. 
During the four firft hours after the eggs are 
emitted, no perceptible change takes place; but 
after that Ij^ace they begin to grow larger, to af- 
iume a lighter colour, and foon after to re-afcend 
to the furface of the water. At the expiration of 
eight hours, the white fluid in which the eggs fwim 
grows more thick; they lofe their blacknefs; and, 
as they increafe in fize, fomewhat of tlieir fpheri- 
cal figure. The twenty-firft day, the egg begins 
to open a little on one fide, and the rudiments of 
a tail to appear, which gradually becomes more 
and more diftinft. On the thirty-ninth day, the 
little animal acquires motion ; it's tail is brandifhcd 
at intervals; and it then becomes evident that the 
circumfufed liquor nourifhes it. In" two days 
more, fome of thefe animalcules fall to the bot- 
tom; while others continue fwimming in the fur- 
rounding fluid with increafed vivacity and motion. 
Thofe v/hich fall to the bottom remain in that 
fituation the whole day; but, after having ex- 
panded themfelves a little, (being hitherto folded 
up) they mount at intervals to the mucus they had 
before quitted, on which they are obferved to feed 
with great alacrity. The next day, they alTume 
their tadpole form; and, in three days more, they 
are perceived to have two little fringes beneath 
the head, which fupply the place of fins ; and thefe, 
in four days after, acquire a more perfe6l form. 
At this period tliey begin to feed greedily on fuch 
weeds as their fituation alTords; and, quitting their 
former food, they derive their fubfiftence wholly 
from them till they arrive at maturity. When 
ninety-two days have elapfed, two fmall feet begin 
to be protruded near each of their tails ; and, four 
days after, they refufe dll vegetable food, their 
mouths appear furniilied with teeth, and their 
hinder legs are compleatly formed. In a day or 
two miore, their arms are compleatly produced ; 
and each of the animals appears wholly perfeft, 
except that it ftill continues to carry a tail. In 
this fin2;ular fituation, the creature refembles at 
once a Frog and a lizard ; which figure it retains 
for about fix or eight hours; and then the tail 
dropping off^ by degrees, the animal appears in 
it's laft and moft perleft form. 
The Frogs having thus changed their figure in 
lefs than a day, are obferved to change their appe- 
tites likewife; and fo extraordinary is this tranf- 
formation, that their former food is ablblutely re- 
jeftcd; and tiiey immediately become carnivorous, 
and prey on worms and infefts; but as the water 
does not fupply thefe in fufficient abundance, they 
are compelled to quit their native element, and to 
feek their food on land. At firft, indeed, their 
imbecillity obliges them to ikulk among bulhes, 
and under ftones; but, when a ihower has once 
fallen and refrefhed the earth, the young animals 
are fecn to quit their retreats, in order to enjoy the 
grateful humidity. On many occafions the ground 
is perfeftly obfcured by their numbers; fome hunt- 
ing for their prey, and others fearching for fafe re- 
treats. From the myriads that thus prefent them- 
felves, fome credulous perfons have conjeftured 
that thefe animals were generated in the clouds, 
and fhowered down on the earth; but, had fuch 
been at the trouble of tracing them to the neareft 
pool, they would no doubt have reafoned in a very 
different manner. 
As the Frog derives the greateft part of it's fub- 
FRO 
fiftence from the land, fo it lives principally oti 
it: however, when the cold nights commence, it 
returns to it's native element, always making choice 
of ftagnant waters, where it can lie concealed at 
the bottom; and there it continues torpid, or at 
leaft poflefTed of very little motion, during the 
winter; like the reft of the dormant race, neither 
requiring food, nor needing any affiftance frorti 
the air. 
The difference of fex in thefe animals i§ not 
perceptible till they have arrived at their fourth 
year; nor do they begin to propagate till they have 
readied that period. Hence, on comparing their 
flow growth with their other habitudes, it would 
feem that they live about twelve years; but fo 
numerous are their enemies both at fea and land, 
that it is probable very few of them reach that 
period which would naturally terminate their lives. 
Frogs, as already obferved, live on infefts, but 
they never devour any not endowed with motion. 
They continue fixed and immoveable till theif 
prey appears; and, when they think it fufficiently 
near, they fpring forward with great agility, dart 
forth their tongues, and feize it with unerring aim. 
The tongue of the Frog, as in the toad, the li- 
zard, and the ferpent kinds, is extremely long» 
and formed in fuch a manner, that it's point is re 
verted down the throat: this offenfive weapon is 
likewife covered with a glutinous fubftance, by 
means of which every animal which it touches ad- 
heres to it, and is thus held faft till it can be 
drawn into the moutli of the Frog. 
But though Frogs are fufficiently predaceous, 
they are neverthelefs capable of continuing a long 
time without food. A German phyfician kept 
one of them for eight years in a glafs velTel co- 
vered with a net; during which long period, it's 
food was at all times very fparing: in fummer it 
was fed with grafs; and in winter, with hay a little 
moiftened. Flies were alfo occafionally put into 
the glafs, which it generally followed with open 
mouth, and caught very expertly. In winter, 
when flies were with difficulty procured, the ani- 
mal generally became lean; but, in fummer, it re- 
covered it's flefli again. It was kept in a v/arm 
room, and feemed always lively, and ready for it's 
prey: however, on the commencement of tlie 
eighth winter, when no flies could be found, it 
languiffced, and died. It is not, indeed, certain 
how long this animal might have lived, had it been 
furniflied with proper nourifliment; but of this we 
are aware, that a very fmall quantity of food will 
fupply the neceffities of thefe creatures. 
The Frog is fo extremely tenacious of life, that 
it will jump about feveral hours after it's head has 
been amputated ; and continue in motion even af- 
ter it has been emboweiled. When ftripped of 
it's flcin, either by cruel children, or experimental 
naturalifts, it appears for feveral hours to feel no 
abatement of it's natural vigour; and we are cre- 
dibly informed, that many of thefe animals, after 
having undergone this terrible operation, have ac- 
quired new fkins. 
The croaking of Frogs is fo well known, that 
from this circumftance, in fome countries, they are 
diftinguiflhed by the ludicrous appellation of Dutch 
nightingales : indeed, tlie noife of the aquatic 
Frogs of Holland is loud beyond conception; and 
it will hardly be credited, that animals of fuch a 
diminutive fize fliouid be able to fend forth notes 
which can be heard at the diftance of three miles ; 
yet this is adually the cafe. According to the 
ingenious 
