394 SUMMARY OF CURRENT RESEARCHES RELATING TO 
Tlie defect of the apparatus appears to be that the medium must 
alter in composition fiom the constant and gradual loss of fluid by 
evaporation, though in other respects its working seems favourable. 
Glass Culture-chamber for Hanging Drops.* — In his researches 
on the ginger-beer plant, Prof. H. M. Ward used the following simple 
form of apparatus for cultivating organisms in hanging drops and in 
various gases under the Microscope. 
The chamber itself is made out of a piece of stout glass tube about 
3 inches long and as thick as possible ; this is drawn out carefully at 
both ends until it looks like fig. 50, I. The narrow tubes must not ho 
Fig. 50. 
I. Tube ready for grinding, the glass being ground down to the levels a a, j 8 j8. 
II. Side view of chamber ready for use. 
III. View of same from above, c, cover-slip ; d, hanging drop ; w, cotton- wool 
plug ; s, glass slide. 
drawn thin, but the glass should be softened and allowed to contract the 
opening. The incomplete instrument now looks like a narrow tube with 
a bulb at its middle. The upper and lower faces are now ground parallel 
until the sides are perforated by circular or oval apertures. 
After sterilizing, the lower aperture is closed by fixing its edges with 
melted paraffin to a sterilized glass slide. The upper aperture is closed 
with a cover-glass fixed on with freshly boiled oil, and the two end tubes 
are plugged with sterilized cotton-wool. 
The apparatus may be used as it stands for banging-drop cultiva- 
tions in air, or, by connecting it with a gas- generator, the cultivation 
Phil. Trans., vol. 183 (1892) pp. 128-97 (5 pis.). 
