ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
G29 
prevent any back flow of fluid wben the gas pressure is lowered from 
cooling of the apparatus. The gas is to be introduced by a gasometer 
or Kipp’s apparatus. 
Fig. 71. Fig. 72. 
c 
D 
The author also describes his application of the methods of Liborius 
and Buchner to the cultivation of anaerobes. 
Bacteriological Examination of Air.* — Dr. R. T. Hewlett finds 
that Sedgwick’s method is the best for the bacteriological examination 
of air. A glass tube of special form 
is employed. This consists of an 
expanded portion A B (fig. 73) about 
15 cm. long and 4*5 cm. in dia- 
meter ; one end of this is contracted 
so as to form a neck A, 2 • 5 cm. in 
diameter and in length ; to the other 
end is fused a glass tube B D, 15 cm. 
long and 0 * 5 cm. in diameter. The 
neck of the tube is plugged with 
cotton-wool, and two wool plugs are 
inserted in the narrow tube, one at 
its open end D, the other about 6-8 
cm. from the wide part C. The 
whole is then sterilized. When cool 
the narrow part of the tube, from 
its origin at the wide part down to 
the first plug B C, is filled with 
powdered cane sugar (No. 50, B.P. gauge), which has been carefully 
dried and sterilized at 120°-130° C. The tube is again sterilized at 
120° to 130° for two or three hours, the greatest care being taken 
not to melt the sugar. After sterilization the tube is ready for use. 
The wool plug is removed from the mouth A, and a measured 
volume of air is aspirated through the layer of powdered sugar by 
* Lancet, July 14, 1894, p. 74 (1 fig.). 
