FIL TERA BLE VI R USES 
629 
Fig. 18.— Seitz filter, set up for filtration of bacterial cultures, toxins or serum. 
Fiu. 19. — Apparatus arranged for Fig. 20. — Apparatus arranged for 
Seitz filter. Berkefeld filter. 
Apparatus for the filtration of bacterial cultures, toxins and serum. The bulb, made 
of heavy pyrex glass, holds 500 cc. It may be of any convenient size. It has two side 
tubes, each with an enlargement to hold absorbent cotton. The tube on the right is 
provided with an adjustable clamp, and is to admit air prior to withdrawing the contents. 
It is closed during the operation of filtering. The tube on the left is connected with 
pressure tubing to a suitable vacuum. The adjustable clamp admits of regulation of 
the suction. The trap below permits of filling suitable receptacles without danger of 
air contamination. The apparatus is sterilized with a plug of cotton in the opening for 
the filter, and one in the opening of the trap. The filter is sterilized separately, and 
mounted when ready for use. The clamp on the rubber tube leading to the lower 
opening is closed during the filtration process, and is opened after the vacuum is released, 
to permit of filling the container. 
This apparatus may be used with either the Seitz or the Berkefeld filter, as shown 
in the illustrations. 
