ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 463 



Improved Culture Media.* — Prof. Deycke and Dr. Voigtlander, as 

 the result of studies on the preparation of culturo media, recommend 

 the following. 



(1) An albuminate nutrient medium. 200 grm. of fat-free horse-flesh 

 are finely minced and rubbed up with 250 ccm. of 3 p.c. caustic soda, 

 and then incubated in an Erlenineyer's flask for 24-30 hours. The 

 filtrate is neutralised with hydrochloric acid and diluted to 3 litres. 

 Next, 7*5 grm. salt and 150 grm. glycerin are added to the solution, 

 which, after having been alkalinised with soda solution, is worked up 

 with agar or gelatin. For some microbes the addition of l # 5-2 p.c. 

 grape-sugar is necessary. 



(2) A pancreatised medium. A pig's pancreas was chopped up and 

 placed on ice for 24 hours, and then treated for several days with a 

 mixture of 40 grm. glycerin and 160 ccm. water. The expressed juice 

 was used in the preparation. 200 grm. of meat were treated as above, 

 and then with ■ 25 p.c. dry carbonate of soda. After sterilisation the 

 mixture was digested, 50 grm. of pancreatic juice for 7-10 hours at 37°. 

 The solution was neutralised with hydrochloric acid, diluted with water 

 to 3 litres, and worked up with glycerin and agar into a substratum. 



Steel Gas Regulator. "j" — The Cambridge Scientific Instrument Com- 

 pany now supply a steel gas regulator of new design for maintaining 

 incubators, baths, and sterilisers at a constant temperature (fig. 98). Its 

 advantages are : — (1) the ease with which it is adjusted ; 

 (2) the risk of breakage is reduced to a minimum ; (3) the Fig. 98. 

 facility for making direct metallic communication with 

 the gas supply, thus avoiding the use of rubber tubing and 

 consequent risk of fire. The instructions for use are as 

 follows. Unscrew and remove the top milled head, then 

 remove the small screw half-way down the steel barrel. 

 Fill the regulator with mercury until it runs out of the 

 screw-hole. Replace the screw firmly and also the top 

 milled head, and see that the gland nut is screwed down 

 tightly to ensure a gas-tight fit. The adjustment for tem- 

 perature is made by the top milled head. To lower the 

 temperature at which the regulator is to work, slightly 

 turn the milled head in the direction of the hands of a 

 watch ; to raise the temperature the head is turned in the 

 opposite direction. The top pipe is the inlet and the lower one the 

 outlet for the gas. A small by-pass prevents the gas flame from being 

 extinguished when the main gas supply is cut off. 



Simple Device for Distributing Equal Quantities of Culture 

 Media.J — A. Robin contrived the ingenious apparatus shown in fig. 99, 

 which is self-explanatory. The end of the rubber tubing a is connected 

 with a funnel into which the culture medium is poured. 



Modification of Kabrhel's Method of Anaerobic Cultivation^ — 

 The modification suggested by Dr. St. Ruzicka consists in filling the 



* Centralbl. Bakt., l te Abt., xxix. (1901) pp. G17-27. 

 t Liat, 1901, pp. 13-14 (1 fig.). 



t Proc. Soc. Amer. Bacterid., 1900. See Centralbl. Bakt., 1" Abt., xxix. (1901) 

 p. 492 (1 fig.). § Centralbl. Bakt., 1" Abt., xxix. (1901) p. 672. 



