510 



SUMMARY OF CURRENT RESEARCHES RELATING TO 



hematoxylin gave quite satisfactory results. The preparation was cleared 

 with xylol, and mounted in dammar. 



Rapid Filter for Agar.* — Drigalski uses the following form of filter 

 for his agar media. It consists of two superposed cooking pots (fig. 63). 

 The upper (F) has a perforated bottom ; it overlaps the side of the lower 

 vessel (U), and holds a 4-fold layer of yellow, unsized, raw cotton 

 wool. In the lower vessel is placed the nutrient 

 solution with agar. The two pots being fixed, 

 the whole is placed in a steamer, where the agar 

 is dissolved ; the wool becomes saturated with 

 steam, and, together with the upper vessel, is 

 sterilised. When the solution is complete, 

 usually within 3 hours, the whole is taken out 

 from the steamer, the upper vessel with the 

 filter is separated, and the contents of the lower 

 vessel is poured into it, and in the course of a 

 few minutes 3 litres of a clear solution are 

 obtained. 



Apparatus for Culture of Bacteria at High 

 Oxygen Pressure. f — A. Meyer's apparatus con- 

 sists of a steel flask filled with compressed air, 

 and fitted with a special reducing valve actuated 

 by screws and levers, by which the pressure of the 

 air emitted from the flask is varied and regulated ; 

 the pressures in the flask and in the reducing 

 chamber being indicated by spring tube mano- 

 meters. The compressed air is passed from 

 the reducing valve, by a connecting tube, into the pressure chamber 

 which is also provided with a manometer and a safety valve, and in 

 which is a vessel for holding the cultures to be examined. The author 

 supplies photographs and diagrams, and a minute description of his 

 apparatus. 



Method for the Bacteriological Examination of Soil4 — Buhlert 

 and Fickendey advocate a modification of Remy's method for the bacterio- 

 logical examination of soil. With a clean spade a hole is dug the 

 depth of a furrow, and with sharp cut perpendicular sides, and from this 

 a spadeful of the soil is removed. The upper surface of this is cleansed 

 by scraping with a flame-sterilised iron spatula ; with a second sterilised 

 spatula the earth is put into a sterilised glass vessel ; 300-500 grni. of 

 the soil are now added to 300-500 c.cm. of sterilised tap water in a glass 

 vessel with a wide mouth and a ground stopper ; after the mixture has 

 been thoroughly shaken for five minutes, a known amount of the washed 

 soil is drawn up in a pipette and inoculated into media. For nitrification 

 and nitrogen fixing 20 c.cm. are employed ; for denitrification and 

 peptone disintegration, 5 c.cm. 



* Centralbl. Bakt., lte Abt. Orig., xli. (1906) p. 298 (1 fig.), 

 t Op. cit., 2 ,e Abt., xvi. (1906) p. 386 (9 figs.). 

 % Tom. cit., p. 399. 



Fig. 63. 



