598 
8UAIMARY CF CURRENT RE8 MARCHES RELATING TO 
the diagnosis of different kinds of bacteria. The medium is made by 
mixing 140 grm. of egg-albumen with 20 grm. of powdered raw coffee. 
After standing for 2 or 3 days, the mixture assumes an emerald-green 
hue, which afterwards becomes darker. After filtering through gauze 
into test-tubes, the medium is sterilised for 2 hours a day for several con- 
secutive days and allowed to set. On this medium the bacteria do not 
become tinted, but the colour around the colonies becomes altered. 
Colonies of Meningococcus and Pneumococcus are surrounded by an orange- 
yellow zone. Thoso of St. py. aureus produce a pale yellow hue, with 
slight liquefaction of the medium ; while Proteus vulgaris strongly 
liquefies the medium with the formation of a red colour. The staining 
of the albumen cannot be referred to the chlorophyll contained in the 
coffee-berries, for this is easily soluble in alcohol, ether, and benzin, and 
insoluble in water. The green coloration is the more inexplicable as 
the reaction is not acid. Mineral acids turn the green albumen reddish y 
but do not decolorise. C0 2 has no action, and 0 turns it darker. If the 
cultures be killed by heating to 100°, or moistened with 1 per thousand 
sublimate solution, the original colour returns. 
Use of Acetylene in the Cultivation of Anaerobic Bacteria.* — 
Dr. J. Ferran recommends the use of acetylene for cultures of anaerobic- 
bacteria. The air in the culture vessels is driven out by means of the 
gas, which is easily prepared. The apparatus for making acetylene gas 
is composed of a 2-litre vessel half filled with w’ater, and closed with 
a caoutchouc plug having two perforations. Through one of the holes 
passes a glass rod, having at the end a hook on which is suspended a 
little basket containing calcium carbide. Through the other hole passes 
a glass tube, connected with a rubber tube, and this latter with the 
culture vessel. The culture vessel is also closed with a doubly per- 
forated stopper. Through one of the holes passes a tube for the exit 
of air, while the other is connected with the rubber tube from the acety- 
lene apparatus. When the connection is made the calcium carbide is 
immersed in the water, and the gas at once develops. As] soon as the 
air is completely driven out, the two tubes of the culture vessel are 
closed, and the calcium carbide drawn up out of the water. 
Culture of Diatoms. f — Herr J. Burger communicates the following 
simple method for cultivating diatoms ( Gomplionema ). The material 
was placed in a glass vessel containing tap-water, some straw, bran, and 
moss. This vessel was covered with tissue piper, and hung up before 
the window in a moderately warm room. The culture was started in 
February, and in April the straw was found to be covered with dia- 
toms. 
(2) Preparing Objects. 
Detection of Protoplasmic Threads in the Cell-wall. — Mr. W. 
Gardiner gives further details of his two methods for demonstrating the 
connecting threads which traverse the walls of plant cells. 
(1) The Kolossow safranin method, in which the tissue is first 
killed and swelled with picric acid, picrosulphuric acid, picro-acetic 
* Centralbl. Bakt. u. Par , l te Abt., xxiv. (1898) p. 29. ; 
t Zeitsclir. f. angew. Mikr., iv. (1898) p. 61. 
X Proc. Cambridge Phil. Soc., ix. (1898) pp. 504-12. Cf. this Journal, ante, p. 240. 
