ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
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point of the apparatus is that it works automatically. It consists of a 
burette (see fig! 121), at the bottom of which is a three-way tap, which con- 
nects with the burette, the reservoir, and the outflow tube. Inside the 
burette is a sort of glass piston-rod, the lower end of which is expanded 
into a chamber containing a float. The chamber is in communication 
with the lower part of the burette by a small aperture, so that when the 
fluid is allowed to flow in from the reservoir the float is pushed up and 
the further ingress of fluid stayed. By giving another turn to the tap the 
fluid runs out at the bottom into the vessel placed there to receive it. 
In this way definite quantities of a nutrient fluid can be safely removed. 
Filtering Apparatus for Fluids containing Bacteria and for Pre- 
ventive Serum.* — Prof. A. Pawlowsky and Dr. G. Gladin have devised 
an apparatus for filtering fluids, especially anti-diphtheritic serum, 
which permits any quantity of the filtrate to be drawn off without risk 
of contamination. The apparatus consists of a glass vessel closed by a 
caoutchouc plug with three openings. In one is a Pasteur’s bougie A ; 
in another is a short bent tube B, and in the third the glass tube 0, the 
end of which reaches nearly to the bottom of the vessel, while the other 
* Centralbl. f. Bakteriol. u. Parasitenk., l te Abt, xviii, (1895) pp. 170-2 (1 fig.). 
