MICROBES, OR BACTERIA. 97 
ventilation. This process is somewhat slow, since it 
only produces ten litres of vinegar out of each tun in 
the course of the week, and it has the disadvantage 
of encouraging the multiplication of anguillide, the 
small nematoid worms which live in vinegar and sour 
paste. 
Pasteur has modified and improved the original 
process so as to obviate both inconveniences. He 
employs heat, which allows the process of acetification 
to be intermittent, and thus prevents the development 
of the anguillide. Shallow vats, about 30 centi- 
metres in depth, with lids in which holes have been 
pierced, are used, and mycoderma is scattered on their 
surface. Gutta-percha tubes, pierced with holes at 
their lower extremity, are placed at the bottom of 
these vats, so that fresh liquid can be added without 
disturbing the superficial film of mycoderma. 
In Germany, vinegar is made by means of spongy 
platinum, or platinum black, which oxidizes alcohol 
without the intervention of a microbe. This affords 
a good example of fermentation, or of an analogous 
phenomenon, produced solely by physico-chemical 
action. The platinum black acts by disintegrating 
the alcohol and placing it in more intimate contact 
with the oxgyen of the air, since the process of 
oxidation would be much slower without either this 
process or the presence of the ferment. 
