1326 Wisconsin Academy of Sciences, Arts, and Letters . 
tubes is put in place, and then a paper bag is put in one side and 
a small tube of gelatin containing a little methylene blue, which 
has just been boiled until it is colorless, is put in on the other 
side for the purpose of determining whether or not anaerobic 
conditions are secured and maintained. The gelatin tube should, 
of course, remain free from a blue color; i. e., the methylene blue, 
should remain reduced. The paper sack is made from newspaper 
(1x3 inches) pasted together, and is used to hold the alkali. It 
requires a short time for the alkali to eat through the bag during 
w r hich time it is possible to close and seal the jar. The outfit is 
incubated for 48 hours at 37° C. In examining them the box 
is removed from the jar, the cover taken off, and the tubes lifted 
out two at a time with a small pair of forceps. The following is 
regarded as a typical reaction: Abundant gas formation, cream 
layer may be forced to top, or even out of tube, otherwise tom 
into shreds; beneath is a floeculent or floating curd. The amount 
of coagulated casein is small in comparison with the amount of 
whey, which is colorless, clear, or slightly turbid. The reaction 
is strongly acid and has the odor of butyric acid. A similar 
change is sometimes seen in which there is lacking, however, evi¬ 
dence of gas and floeculent curd, and in which the curd remains 
at the bottom. In doubtful cases, as for example, where this last 
change occurs with milk very good in every other way, it would 
be desirable to test out the tubes by sub-cultures. For this purpose 
a milk fermentation tube is excellent. A new form of fermenta¬ 
tion tube, not previously described, useful in this connection may 
properly be considered here. 
2. New Form of Fermentation Tube Used for Testing out 
Doubtful Reactions in Bacterium Welchii Determinations. 
This form of the fermentation tube was devised some years ago 
for some special problems still under way, and is especially use¬ 
ful for the study of anaerobes and the amount and rate of gas 
formation from a constant volume of the medium. 
Its special features are best understood by reference to the ac¬ 
companying figure. Fig. 10. (A) lower arm A is the essential 
modification of the ordinary form. This is made of such size 
that it will contain a measured amount of culture medium, say 10 
c. c. On top of this is put an oil (white paraffin or other neutral 
oil) filling the closed arm B, and some in the bulb. The medium 
is inoculated by means of a capillary pipette. The gas, as it is 
