198 ORIGIN OF MOULD. V. 
The ftalks being very fine near the fummit, and 
bearing on the vertex a round corpufculum, which 
ofcillates the filament by its own weight, as the 
ear of corn occafions ofcillation of the ftalk, we 
may eafily perceive that every breath of air, 
however gentle, will bend, break, and deftroy 
their moft delicate texture, which does not en- 
fue when the moulding fubftances are put under 
a receiver. Befides, their humidity is better pre- 
ferved, a condition moft effential for the produc- 
tion and increafe of mould. In the courfe of 
thefe obfervations, I have always ufed_ receivers. 
‘The prejudicial confequences of agitated air are 
vifible, fig. 1. which reprefents two {pots of 
mould with heads, viewed with the naked eye 
when taken from under the receiver, and expo- 
fed a fhort time to the action of the air : their na- 
tural direction is loft, and the ftalks bend in vya- 
rious directions. 
Some fubftances, put in a fituation to acquire 
mould, gradually difflolve into a kind of acid 
fluid, wetting the circumjacent parts; it is pre- 
cifely here that the mould hitherto mentioned 
fprings. A fimaller portion of moifture likewife 
exhales from the fame fubftance, which adheres to 
the infide of the receiver, in the form of a pellucid 
aqueous veil, and increafes fo confiderably as to 
form large drops that run down the fides of 
the receiver in winding ftreams : an equal quan- 
tity 
