ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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By mixing this sediment with liquefied gelatin, and pouring it into test- 
tubes, or flattening it out between two glass plates, an equally coloured 
green cast or plate is obtained which serves excellently for studying the 
action of light on chlorophyll and the excretion of oxygen. 
Fig. 11. 
Flat Flask for cultivating Micro-organisms.* — Dr. J. Petruschky 
has devised a convenient apparatus for cultivating micro-organisms on the 
plate or surface principle. It is merely a flat flask, and is made in two 
shapes. Shape A is made 
of thin lamp-glass, and the 
B shape of thick or plate 
glass. Both have pretty 
much the same form; that 
is, they are flat and some- 
what triangular, or rather 
like a flat worm. Their 
general aspect is seen from 
the illustrations, which give 
a front and side view, and 
also the view down the neck 
when looked at from above. 
There is a slight difference 
in the measurements ; those 
of the A pattern being, 
height 10-11 cm., breadth 
5J-6 cm., width (same 
measurement as neck) about 
1J cm. In the neck there 
is a circular indentation. 
The measurements of the 
B pattern are, height 12*5 
cm., breadth 6 cm., width (same as neck) 2 cm. In this pattern the 
indentation is confined to the broad side of the neck. 
The A pattern is more suitable for delicate work, such as the dif- 
ferentiation of typhoid colonies, while the B form suffices for isolation, 
enumeration, and inoculation purposes. 
These flat flasks are specially adapted for the bacteriological 
examination of water, and for the cultivation of anaerobic microbes in 
hydrogen. 
Apparatus for filtering perfectly clear Agar.j — Dr. J. Karlinski 
has invented an apparatus for filtering agar, and though it agrees 
with that devised by Jakobi, differs from the latter in that its intention 
is, besides obtaining a perfectly clear solution, to prevent the too quick 
cooling and setting of the medium. 
The apparatus, seen in section, fig. 12, consists of a tin vessel a , the 
upper end of which is closed with a perforated caoutchouc plug, and its 
bottom ends in a tube fitted with a stopcock. 
The vessel a is surrounded by the vessel 5, made of similar material, 
and from near the bottom passes out a short closed pipe. The space b 
* Centralbl. f. Bakteriol. u. Parasitenk., viii. (1890) pp. 609-14 (3 figs.), 
t T. c., pp. 643-5 (2 figs.). 
