ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
679 
means of litmus paper. This is quite a simple process, and merely 
consists in adding a drop of phenolphthalein to 1 ccm. of bouillon, and 
then dropping in 0 * 4 per cent, caustic soda solution until a pale rose 
colour appears. Phenolphthalein is a greyish-yellow powder, and 
dissolved in alcohol (1 to 300) is almost colourless, but on the addition 
of an alkali turns dark red. This sensitiveness to alkalies renders it a 
convenient reagent for measuring the amount of alkalinity of nutrient 
media. 
Bouillon should be neutralized before either agar or gelatin is 
added. Agar requires to be boiled for quite a long time before it is 
completely dissolved, while gelatin should only be boiled for a very 
short time. 
Preserving Malaria-Plasmodia alive in Leeches.* — Dr. N. Sacharow 
finds that leeches ( Hirudo medicinalis) may be used for keeping alive 
the plasmodia of malaria. The leeches were frozen in a piece of ice 
and kept in an ice-cellar for a week, the plasmodia being found at the 
expiration of this time quite unchanged. Their mobility was even 
greater than when taken directly from the blood of a patient suffering 
from malaria, though their form was somewhat altered and their size 
diminished. 
Cultivating Spirillum Obermeieri in Leeches.| — Dr. Th. Pasternacki 
gives the result of fourteen observations made by means of leeches on 
Spirillum Obermeieri, from which it seems that this micro-organism is 
very resistant to low temperatures. The leeches were filled with blood 
from cases of relapsing fever, and a drop of blood was obtained for micro- 
scopical examination by placing some salt crystals on their tails : this 
caused the leech to evacuate a drop of blood on a cover-glass placed 
ready for the purpose. 
Directly after sucking the relapsing fever blood the leeches were 
exposed for various lengths of time to temperatures varying from 0°-40°, 
and then if alive, a specimen of the blood was obtained in the manner 
described. 
New Cultivation Medium for Bacteria.^ — Dr. P. Kaufmann states 
that he has obtained very favourable results from the use of jequirity 
as a cultivation medium. The solution is prepared in the following 
manner : — 10 grms. of jequirity seeds are pounded in a mortar to remove 
the husks, and this reduces the weight to about 8 grms. The 8 grms. are 
then boiled in a steam sterilizer with 100 ccm. water for two hours, and 
when cold filtered. The fluid thus obtained is of a yellow colour, with 
a neutral or very slightly alkaline reaction, and after sterilizing in the 
usual manner, can be used without further addition or treatment as a 
medium for cultivating bacteria. 
From their behaviour to the jequirity solution the bacteria were 
divisible into three classes : — (1) in which the colour remained unchanged ; 
(2) in which it was discharged ; (3) in which a green colour was produced. 
A further examination showed that the green cultures had an alkaline 
* Wracz, 1890, pp. 644-5. See Centralbl. f. Bakteriol. u. Parasitenk., x. (1891) 
p. 199. 
t Wracz, 1890, p. 297. See Centralbl. f. Bakteriol. u. Parasitenk., x. (1891) 
pp. 198-9. % Centralbl. f. Bakteriol. u. Parasitenk., x. (1891) pp. 65-9. 
3 b 2 
