woh ORIGIN OF MOULD. Vv 
ed it on fome vegetable fubftances, and faw them 
covered with mould. But the Bolognefe Profef- 
for repeated Micheli’s experiment without find- 
ing it fo conclufive; the vegetable fubftances 
being equally covered, though no duft was put 
upon them. Thus the queftion was undecided, 
for I do not know that any other perfon has at- 
tempted to folve it. Perhaps I fhall be taxed 
with prefumption for faying, that, by means of 
experiments analogous to thofe of Micheli, it has 
‘been in my power to-afcertain the faét, but ex 
periments much more numerous, diverfified and 
connected, which I muft be permitted to narrates 
Two pieces of moiftened bread were taken, as 
fimilar to each other as poffible, and from the 
fame loaf, fo as to be perfectly equal ; and I en- 
deavoured to attain the fame equality in all the 
reft of my expertments. One piece was f{trewed 
with duit, taken from a quantity of ripe mould 
heads, in fuch a manner that the furface was 
faintly blackened: the other was untouched, on 
‘purpofe to compare the production upon each. 
This was done in fummer. Next day, the /fown 
fubftance,—but, for brevity it may be obferved, 
that by this is meant the fubftance of whatever 
mature covered with duft; and by unfown, the 
other vegetable fubftance not covered,—on the 
fown fubftance, I fay, a fhade of mould appear- 
ed, ‘whereas on the unfown was none. Before 
the 
