360 FIRST FORMS OF VEGETATION. 
piece of boiled tripe. It is usually placed in a 
small jar containing a solution of sugar or treacle ; 
and after being allowed to remain in a warm situa- 
tion for a month or six weeks, the solution is con- 
verted into vinegar, this change being due to a 
kind of fermentation caused by the plant. If the 
vinegar plant be left however in the liquid after it 
has transformed the sugar, it oxidizes the vinegar, 
and leaves the housewife who has neglected to re- 
move it at the right time only dirty water for her 
pains. The same substance, it may be remarked, 
exists as a delicate diffused organic film when 
other modes of vinegar-making are adopted. It 
covers the beech or deal shavings, dried and soaked 
in strong vinegar, over which German manufac- 
turers cause an alcoholic mixture to trickle slowly 
when they wish to promote its acetification. . After 
a few days, when the vinegar-plant has had time 
to grow, the process advances with great rapidity. 
The so-called vinegar-plant is only an abnormal 
form of the common Pentcillium crustaceum or 
blue mould. In fact it is merely the spawn or 
mycelium of that plant, increased to an extraor- 
dinary extent and closely interlaced together, 
owing to the absence of the usual spore-bearing 
stalks, which, as already remarked, are never 
formed in fungi growing in fluids. Whenever the 
vinegar is allowed to evaporate, and the mycelium 
