208 ORIGIN OF MOULD. NM 
for which purpofe it was proper to cover mould: 
ing fubftances with duft taken from different 
vegetables, different earths, and other matter 
volatile from extreme minutenefs. It feemed, if 
the other duft could contribute to render fubftan- 
ces more fit for producing mould, that it alone did 
not poflefs this property. The roots, ftalks, and 
heads of mould, ftill unripe, were not {pared. 
They were dried, and reduced to fine powder, 
but without effe@. For the moft part, inftead 
of the ufual quantity of mould appearing, they 
deprived the fown fubftances of the power of pro- 
ducing it; and that powder, which did not pre- 
vent the production, diminifhed the quantity of 
what the unfown fubftances ufed to produce. All 
thefe united facts feemed to prove, that the gra- 
nuli, proceeding from ripe mould heads, are rH 
vegetable feeds. 
During the courfe of my experiments, I was 
curious to learn whether the feed would germi- 
nate when fown on fubftances that naturally did 
not mould. A quantity was fown on hard bo- 
dies, as glafs, metals, ftones, alfo on blot fheet, 
writing paper, cotton, fponge, and the like. All 
the fubftances were kept moift: but no traces ap- 
peared except fome filaments, which were per- 
ceptible on fponge. Certain circumftances are 
requifite for the expanfion of the feeds, and 
thefe are found only in particular fubftances. 
o, ine 
