ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 411 



been removed for examination of contents. The metal box to hold the 

 water is now made almost flat, which will allow any sediment to settle at 

 the bottom. If the water is very muddy, a cork can be fitted into the 

 outlet hole and left until the debris has settled, first filling the tube with 

 clean pond-water. If the cork is carefully removed, very little, if any 

 dirt will pass down the tube. Should some slip by, this can be trapped 

 off, and the tube refilled with water, when a perfectly clear gathering can 

 be secured. A strainer is provided, to be used, when necessary, for re- 

 moving larvae or any of the entomostraca. 



It is important that as much light as possible should be concentrated 

 on the glass tube. To arrange for this a bi-convex lens, \\ in. diam., 

 silvered on one side and mounted in a metal holder with a movable 

 support allowing it to be tilted at an angle, is placed under the tube, light 

 from a bullseye condenser is received by the lens, and a bright beam 

 passed up the tube. This method of transmitting the light is very 

 effective, and the trap in consequence acts more rapidly and effectively 

 than when the bullseye condenser only is employed. The lens, placed in 

 position, is shown in the illustration. 



New Hsemoglobin-agar Medium for the Cultivation of Bacillus 

 influenzas.* — W. Thalhimer, having failed to obtain satisfactory growth 

 of Bacillus influenzse on crystalline hasrnoglobin-agar, has devised a 

 culture medium prepared with amorphous haemoglobin, which has given 

 encouraging results in his hands. The new medium is prepared as 

 follows : Dissolve about 10 c.cm. of amorphous powdered hgemoglobin 

 in 100 c.cm. distilled water and filter through a Reichel porcelain filter. 

 Add a sufficiency of the filtrate to fluid agar to give it the colour 

 intensity of ordinary blood-agar. The mixture is then poured into 

 tubes and slanted. With regard to the failure of crystalline haemoglobin, 

 it is suggested that in the process of crystallization the haemoglobin 

 becomes so changed that it is no longer available for the growth of 

 B. influenzse. 



New Method of Investigating Anaerobic Stab Cultures. f — Konrich 

 recommends the following method of obviating the difficulties that usually 

 attend the abstraction of culture material from " stab cultures," which 

 not infrequently involve the breaking of the test-tube and the contamina- 

 tion of its contents. Seize the culture tube with a Cornet's forceps near 

 the middle ; remove the plug and flame the edge and upper part of 

 the tube, which is then introduced between the two halves of a sterile 

 Petri dish. Now hold the lower part of the test-tube for a moment in 

 the Bunsen flame till some of the agar becomes liquid. The small 

 portion of liquid agar becoming vaporized expels the agar column (just 

 as the expansion of steam drives forward the piston of a steam-engine), 

 which glides uninjured into the Petri dish, where it can be cut longi- 

 tudinally or in cross-section and the culture material conveniently 

 abstracted. During the expulsion of the agar hold the test-tube slightly 



* Centralbl. Bakt., lte Abt. Orig., lxxiv. (1914) pp. 189-90. 

 t Centralbl. Bakt., lte Abt. Orig., lxxiv. (1914) pp. 191-2. 



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