812 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
since it is not advisable to produce all gradations of magnification by 
displacement alone. 
Fig. 88. 
Glasses for keeping Immersion Oil.* — Dr. W. Behrens describes 
a convenient bottle for keeping immersion oil, which has been made by 
the firm of Zeiss. It is of cylindrical form, 60 mm. in height and 
30 mm. in diameter. It has a wide neck with a clear diameter of 
15 mm., and holds 20 ccm. of liquid. Above the ground neck fits a cap, 
to the centre of which is attached a cylindrical solid glass rod reaching 
nearly to the bottom of the bottle. This rod has at its upper end a 
glass hemisphere which is cemented by shellac into a corresponding 
hole in the glass cap. It is 60 mm. long and 1 • 5 mm. in diameter. At 
its lower end it is not simply swollen, but is terminated by a small 
glass ball of 2 mm. diameter, which prevents the oil from dropping off. 
C4) Photomicrography. 
Magnesium Flash-Light in Photomicrography.! — Dr. R. Neuhauss 
gives an account of different flash-lights which have been made use of 
for photomicrographical purposes. By mixing different powders it is 
* Zeitschr. f. Wiss. Mikr., viii. (1891) pp. 184-5. f Tom. cit., pp. 181-4. 
