72 ANIMALS AND VEGETABLES» II. 
gaufe the lentil was completely confumed. The ° 
tadpoles were young: I repeated the experiment 
on grown tadpoles, whofe limbs had already be- 
gun to appear; chufing this period to learn 
whether they underwent their metamorphofis in 
ftagnant air. Several did undergo it, and di- 
welted themfelves of the tadpole form to affume 
that of the frog; but others perifhed before at- 
taining their new ftate. 
Animals inhabiting the waters are not under the 
fame neceflity of continually refpiring air, as 
thofe deftined by nature to live amidft the air 
itfelf: therefore it was fit to make fome experi- 
ments on the latter. And having made feveral-on 
tadpoles, that is, on a fpecies of animals chang- 
ing their ftate, I was defirous to repeat them on 
other animals of the fame nature, Caterpillars 
immediately occurred; and my firft experiments 
were on filk worms. ‘Thofe that were taken 
would in a few days have begun to fpin their 
web. Leaving them on a mulberry branch, the 
ligneous extremity of which was immerfed in 
water, that the verdure of the leaves might 
be fome time preferved and ferve for food, 1 
fealed them hermetically in a veflel. Above a 
third perifhed; but the reft, kemg eleven in 
number, proceeded as ufual; they worked the 
accultomed web, fixed to the fide of the veffel, 
and there fhut themfelves up. - Butterflies came 
from 
