Th SEMINAL VERMICULIs | 59 
perithed. imicanaintely ; the animalcula in a few. 
minutes, 
_ The great difference of aliment to which vere, 
miculi muft be accuftomed, on pafling from with- 
out into the femen of animals, feems to me a 
fufficient reafon why that cannot be their origin. 
For the fmall animals of our world perifh when 
obliged to change their food, as we fee in cater- 
pillars feeding on fpecific plants; when the plants 
are changed they die: fo that, if we give filk 
worms any other than mulberry leaves they very 
foon fuffer. That infe@ts fhould die, it is not 
neceflary the plants fhould be changed, even a 
change of the parts that they naturally occupy is 
fufficient. Let us confider thofe whofe common 
abode is on the fame tree: and how many hun-. 
dred fpecies inhabit the pear? Some feed and 
dwell on the ligneous parts; fome infinuate 
themfelves between the bark and the wood, and 
never leave them; fome conceal themfelves by 
folding feyeral leaves together, and feed on the 
moit delicate parts; others prefer the roots, and, 
by penetrating, form tumours there ; fome menace. 
the flowers, and others the fruit. Let us change 
this order; let us tranfport the infects of the 
wood into the bark, and reciprocally ; thofe of 
the leaves to the roots, and fo on with the refi; 
it will not be long before they die. I cannot 
conceive why the fame fhould not happen ta 
fperinatic 
