Te 
200 ORIGIN OF MOULD. V. 
roots, Numerous twigs and branches proceed 
from each, which are frequently of as great dia- 
meter as the parent {talks whence they originate. 
While the ftalks fucceflively vegetate and ex- 
_ tend, feveral groups of {maller branches {pring 
out laterally, with minute heads at the vertex. 
Thefe are partly fungi-form, partly globular, and, 
as the ftalks rife, they blacken and come.to ma- 
turity. Additional new ftalks next appear ; and 
multiplication continues fo long as the mould 
vegetates. This little foreft of filaments is ter- 
minated by moft minute points, and wholly co- 
vered with black globules. 
Thus does mould ariginate and aryive at ma- 
turity. We need not inquire whether it is a real 
vegetable: it evidently is fuch, by the obferva. 
tions I relate. But thefe vegetables, or microfco- 
pic plants, do not poflefs two properties common 
to other plants. Ligneous and herbaceous plants, 
expofed to natural light, always tend to take a 
direction perpendicular to the horizon, They en- 
deavour to attain it when an impediment intervenes. 
‘The experiments of M, Bonnet are excellent, as 
may be feen in his work Sur l’ufage des Feuilles. 
But we do not fee this tendency to perpendicularity 
in mould ; for, although many {talks are perpendi- 
cular, it is not eflential to their nature, and in- 
yumerable others are in a different dire@tion. If 
a plant grows in the rent of a wall, though it firft 
appears 
