12 
Slack, on the Vinegar Plant. 
The ' Micro^raphic Dictionary' contains a digest of various 
observations made upon this plant. The general mass of the 
plant is described as a structureless jelly, having polymor- 
phus structures imbedded in it, and " exhibiting transitions 
which/' as the writer says, " render it impossible for them to 
be regarded as of distinct origin." Amongst the imbedded 
objects, the ^ Micrographic Dictionary ' speaks of cells like 
yeast, l3ut generally elliptical, of others with short cylindrical 
joints, and of long tubular filiaments terminating in elliptical 
cells, so as to resemble oidium. Branched filaments are 
likewise mentioned, and it is stated that when a vinegar 
plant is left upon a solution after the saccharine matter has 
been separated, patches of blue, green, and yellow mould — 
Penicillium glaucum — appear. From these facts, the writer in 
the ^ Micrographic Dictionary' considers that the vinegar 
plant may be regarded as the mycelium of the Penicillium 
glaucum vegetating actively, and increasing by crops of 
gonidia or gemmae. It is also stated that yeast-cells are 
not to be distinguished from cells found in the vinegar plant. 
An examination of the vinegar plant with low powers, 
shows no more than the ^ Micrographic Dictionary' describes ; 
but if very thin portions are carefully illuminated and 
viewed under a magnification if from one to three thousand 
linear, it will be found that the gelatinous matter, hitherto 
treated as structureless, contains millions of small bodies 
resembling the bacteria that occur in the pellicle of solu- 
tions set aside to develope infusoria These bodies vary con- 
siderably in size, some not exceeding two o-^' length, others 
twice as big, or more. If stained with iodine, they some- 
times become a little plainer ; but the more delicate will not 
appear as beaded structures to an observer coming quite 
fresh to their examination. I do not think all are beaded, 
and some seem to be in an intermediate stage. The number 
that can be made out as beaded will depend upon the time 
employed in the investigation ; and in the course of a week or 
two an observer will be able to trace their structure to a 
sufficient extent to justify the belief, that all either possess, 
or tend towards, the bacterium form. I believe the yeast 
plant is commonly associated with bacterium-like bodies, and 
probably when their number is moderate, they do not notice- 
ably interfere with the vinous fermentation. In the vine- 
gar plant they are so numerous as to suggest the idea that 
they play an important part in the complicated series of 
actions which the plant, as a whole, excites. When a solu- 
tion of common sugar is converted into vinegar, a series of 
processes occur, every one of which seems to be correlative 
