362 FIRST FORMS OF VEGETATION. 
for the production of vinegar. This remarkable 
mode of propagation by dividing into separate 
laminz, which has been taken advantage of in 
spreading specimens of the plant, resembles the 
separation of buds in the medusz, and the meris- 
matic mode of division by which the diatoms, and 
many others of the lowest class of alge, extend 
themselves indefinitely ;—thus showing the close 
and intimate connexion subsisting between plants 
that in other circumstances are widely different, 
when placed under similar conditions. 
v A still more striking form of the protean 
‘mould under consideration, is that which occurs 
in the fermenting of yeast and other substances. 
Indeed, some botanists are of opinion that the 
vinegar-plant is the vegetative growth of the mould 
taking place at low or ordinary temperatures in 
highly saccharine liquids; while the yeast-plant 
is formed in the more rapid fermentation taking 
place at more'elevated temperatures. It may sur- 
prise many to be told that yeast is merely an un- 
developed condition of the common mould which 
they see on their bread and cheese. Fermentation 
is in one sense a chemical process, forming the 
first step towards dissolution, or that re-arrange- 
ment of old elements which is necessary to form 
new compounds ; but, strange to say, the action is 
also vegetative. The whole mass of fermenting 
