398 SUMMARY OF CURRENT RESEARCHES RELATING TO 
inserted so that the openings therein coincide with those in the neck. 
The air can then be exhausted by an aspirator attached to one of the 
tubes or the vessel filled in an analogous way with hydrogen or carbonic 
acid. If hydrogen, it is advisable to put the gas in at the top and draw 
out from the bottom, i. e. through the tube opening, and conversely with 
carbonic acid. 
The apparatus is also adapted for the absorption method of cultiva- 
tion. A strong solution of caustic potash or soda is placed at the bottom 
Fig. 31. 
of the vessel, the inoculated tubes are put in, and the stopper having 
been inserted, a strong solution of pyrogallic acid is aspirated through 
the tube in the stopper. 
A less costly substitute is easily made out of a wide-mouthed bottle 
fitted with a caoutchouc stopper perforated with a couple of holes, into 
which are inserted a couple of glass tubes bent at right angles. Both 
of these are fitted with stopcocks, and one reaches nearly to. the bottom 
of the bottle (fig. 31). 
Apparatus for Bacteriological Examination of Air.* — Dr. H. 
Cristiani describes the following method for examining air obtained at 
considerable altitudes from a balloon. A flat-bottomed flask is hermeti- 
cally closed with a rubber plug perforated by two holes for the passage 
of two glass tubes (fig. 32). The tube a is bent, and is stopped in two 
places with cotton-wool plugs. Its lower leg only just reaches below the 
Ann. Inst. Pasteur, vii. (1893) pp. 665-71 (1 fig.). 
