A hey GL Gas ALO ERY: 
the two hinder legs, ¢. The difference, how- 
ever, between the {mall and great guts was not 
very confiderable in the Vadpole ; nor is it very 
remarkable in the human feetus, in which 
there is, at firft, very little difference between 
the {mall gut, colon, and rectum; as J can 
demonftrate in a human feetus fix months old. 
The moft remarkable thing in this little ani- 
mal was, that only the rudiments ef wu the 
two hinder feet of the Frog were yet .feen ; 
and from them the toes, not yet ftrengthened 
inwardly with bones, began to fwell, as a 
branch does out of a tree; though the figure 
and conftruction of the feet was, however, 
pretty perfect and evident. But as to the two 
fore legs, not even the leaft veftige of them 
yet appeared outwardly, becaufe they lay xx 
hidden, covered and enclofed under the fkin: 
nor did they come in view before the fkin was 
cut open in that part, and then they were feen 
fituated above the lungs and below the gills, 
though they were not fo perfect as the hinder 
feet. 
It is evident, from what has been faid, that 
this animal may and ought to be confidered, 
in its original, as a real infect, fince it hides its 
limbs under the fkin, and thefe increafe there 
until the change of the laft fkin is near at hand; 
at which time it is obferved in infects, that they 
are, as it were in an inftant of. time, tranf- 
formed into other creatures, and exhibit to 
view fuch limbs as they did not before appear 
to have. The fame thing likewife holds in 
young Frogs or Tadpoles: wherefore this ani- 
mal ought to be placed in the fecond order or 
clafs of our natural changes, unlefs the juft 
laws of method had commanded me to treat 
of it at the end of this work, in order to make 
the likenefs between animals which have a red 
blood, and thofe which contain white, yellow, 
or green blood in their heart and veffels, the 
more evident. 
As we fee infects lofe many parts with their 
old fkin, this is likewife the cafe in the Frog ; 
which, befides other things, plainly cafts off its 
mouth and tail: fo that, however admirable 
the art, order, conftruGtion, and parts of its 
members may appear to be; yet the nerves, 
arteries, veins, cartilages, mufcles, and many 
other remarkable parts, which gradually vanith, 
and are, as it were, become infenfible, are de- 
ftroyed at once, ceafe their motions, and {top 
their feveral functions, on the change. Are 
not thefe changes admirable? And do not they 
lay before our eyes the omnipotent hand of 
God, confpicuous in his inacceflible radiancy 
and infinite majefty? He, in this cafe, forms 
another out of one and the fame animal, which 
though different in appearance, yet remains one 
and the fame creature. May not the refurrec- 
tion of the dead be exemplified in this illuftri- 
ob MECN She Ca. Si IIg 
ous inftance? All this is very elegantly mani-+ 
fefted in various infects. 
As the want of fubjects now prevents my 
being able to inveftigate further the moft arti- 
ficial compofitions and changes of the limbs 
in the Tadpole, I fhall here’defcribe only the 
mufcles, which are moft regularly placed in the 
middle of the tail, and merit very particular 
notice. Thofe mufcles are laid fomewhat 
obliquely, and converge, Tab. XLIX. Fig. 1. 
yyy, to each other from the two fides of the 
tail towards the middle; and each of them is 
likewife divided into many moving fibres. That 
this may appear the clearer, I have delineated 
them as if they lay outwardly on the fkin. On 
each fide of the mufcles is feen zz the mem- 
branous {kin of the tail, marked with beauti- 
ful points: by the help of this part the Tad- 
pole moves its tail, and fwims, fince it ufes it 
like an oar, to pufh its body forward, with a 
ferpentine motion. 
Before I proceed to other obfervations, which 
I have made on the full-grown Frog, I thall 
give the method whereby the Frog changes its 
ikin. I would have it obferved, that 1 here 
treat of the largeft {pecies of Tadpoles, fince 
the other kinds are much fmaller. To which 
I muft add, that I increafed it a little above 
its natural fize, in order to explain more in- 
telligibly the metamorphofis of the fkin. The 
time when the young Frogs begin to catt 
their fkin, and to put on the form of a Nymph, 
is with us about the middle of June, or 
fomewhat later; that is, a little more than 
two months after they come out of their eggs. 
When this time approaches, the fkin of the 
-young Frog is firft ufually burft in the back, 
near the head, and through this chink the 
young Frog immediately puts forth its head. 
Then is feen the mouth lying, Fig. 11. @, in 
the Tadpole’s exuvie; and this is obferved to 
differ much, 4, from the wide opening of the 
Frog’s mouth. Then the Frog turns out its 
firft pair of legs, which lay tll now hidden 
under the fkin, cc, and at the fame time it 
prefles back the fkin towards the hinder parts. 
Thus the reft of the body, the hinder legs, 
dd, and alfo the tail, are {tript of their fkin : 
after which we {fee the tail contracted more 
and more every day, until at laft no veftige of 
it appears. If the Frog thus produced be a 
male, two pneumatic kidneys ee are difco- 
vered on each fide of the head, behind the 
eyes; and the great toes of the fore feet appear 
alfo thicker and longer ff than in the female. 
But what parts in particular are left in the 
exuvie, and whether the gills be difcovered 
adhering to them, I have not yet examined. 
After the fame manner. Toads and Water- 
Newts caft their tkin. 
of 
