BACTERIOLOGY AND MYCOLOGY OF FOODS 
CHAPTER I 
BACTERIOLOGICAL APPARATUS 
THE apparatus which is required in a bacteriological laboratory is 
similar in many respects to that used in a chemical laboratory. Since 
chemical methods are often used for studying bacteria, it is evident 
that much the same apparatus may be used. ‘There are several types, 
however, which may receive special consideration, since a proper con- 
struction and type is essential for the best results in bacteriology. 
Fermentation Tubes. There are several types of fermentation 
tubes any of which may be used provided they hold a sufficient excess 
of the medium over the sample under examination. Standard Methods 
for the Examination of Water and Sewage, 1917, recommends that the 
fermentation tubes used in water analysis should hold four times as 
much medium as sample. All fermentation tubes are constructed with 
a closed arm which retains the gases that are given off in bacterial 
metabolism. There are three general types now in use by bacteriolo- 
gists, Brown’s, Smith’s (1890), and Durham’s (1898). 
The Brown fermentation tube was devised for use in connection 
with water analysis and is quite similar to Smith’s. The Smith tube 
is made both with and without glass feet. Those without the glass feet 
require a special rack but have the advantage over those with feet that 
they do not fall over so easily. A convenient rack for holding Smith 
tubes has been devised by Bain (Ill. State Water Survey Bull. 6, 31, 
1908). The Durham tubes are the most satisfactory of all since they 
are made from ordinary test tubes. The inner tube, according to Lee, 
should be cut off at an angle to allow the ingress more readily of motil 
bacteria. Hall (1914) also found this to be true. The efficiency of the 
Smith and Durham tubes was compared by Browne (1913) and Lee and 
Fegely (1914). These investigators found that in low dilutions the 
