ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
557 
punching out pieces from a paraffin plate. The discs should have a 
diameter a little larger than that of the test-tube. They may be steri- 
lized in sublimate and kept covered up ready for use. When required 
they are warmed a little and the cotton-wool plug having been burnt 
and removed, the disc is inserted and jammed into the opening so that 
Fig. 65. 
the tube is now hermetically sealed. In case tubes thus prepared are 
to be kept at a higher temperature the cap is perforated in order to 
allow the gas or air to escape, and the hole afterwards sealed up with 
fresh paraffin. 
(4) Blood-serum is obtainable very satisfactorily in the following 
manner. The flasks (fig. 65) may be made of any size and to hold 
10-100 cm. or more. The broader of the two tubes is plugged with 
cotton-wool, while the other is drawn out to a fine point and closed. 
The artery, from which the blood is to be drawn, having been ex- 
posed is tied in two places. The ligature farthest from the heart is 
drawn tight, while the proximal ligature is merely loosely tied ; just 
above this the artery is clamped. An opening is then made between 
the two ligatures and the thin tube of the flask (its end having been 
broken off) is inserted into the artery, and the loose ligature drawn 
tight so that it holds both tube and artery. The clamp is then released. 
When sufficient blood is obtained the artery is compressed, and the 
apparatus having been withdrawn the fine tube is sealed up in the 
flame. In this way 2-3 flasks full may be obtained from each 
animal, and with a strong probability that they will be sterile. After 
coagulation the serum may be withdrawn with a pipette. 
Preserving Malaria Parasites alive.* — In a case of typical tertian 
ague, Dr. 0. Bosenbach put a leech over the spleen ; this died in 48 hours 
aud numerous dead plasmodia were found therein. Two other leeches 
* Berlin Klin. Wochtnschr., 1891, No. 34. See Centralbl. f. L-aktcriol. u. Para- 
sitenk , x. (1891) p. 806. 
