470 SUMMARY OF CURRENT RESEARCHES RELATING TO 



The inclination of the platform is such that the liquid contained in 

 the tubes is not able to come in contact with the cotton-wool plugging 

 them. When the apparatus is working the liquid is given a to-and-fro 

 movement, which is sufficient to shake up the whole mass. 



Pure Cultures of Diatoms.* — 0. Richter has found that by the 

 aid of the Koch-Beijerinck isolation method on agar cultivations of 

 diatomsf can be obtained in a pure condition so that sub-cultures can 

 be made on gelatin. The agar medium is made by washing 10 grin.. 

 agar in running water for 2 or 8 days, and then in distilled water, 

 frequently changed, for one day. The mass is then dissolved in boiling 

 distilled water, and after filtering, made up to 1000 c.cm. with distilled 

 water. Then are added 0'2 grm. KN0 3 , 0-2 grm. K 2 HP0 4 , 0'2 grm. 

 MgS0 4 , 0-2 grm. CaS0 4 , and a trace of FeS0 4 . The reaction of the 

 agar should be slightly alkaline. 



It was found that the CaS0 4 might be omitted with the advantage 

 that 2 p.c, 1*5 p.c, " 7 p.c, and ■ 5 p.c. agar could be used. 



The gelatin medium is made by soaking 100 grm. white gelatin in 

 700 to 800 c.cm. distilled water for two or three hours and then dis- 

 solving it. The solution is made up to 1000 c.cm., and then 0*2 grm. 

 K 2 HP0 4 and 0-2 grm. MgS0 4 , and a trace of FeS0 4 added. The 

 solution is made slightly alkaline with soda and cleared with egg- 

 albumen. 



New Method of Demonstrating Typhoid Bacilli.; — W. Hofmann 

 and M. Ficker recommend the addition of coffein to media as it inhibits 

 the growth of B. coli communis, though it has little influence on other 

 water bacteria. The medium used consisisted of beef 1 kilo., pepton 

 60 grm., salt 5 grm., water 1*5 litre, reduced to 1 litre by boiling- 

 One part of this stock fluid is mixed with an equal bulk of 1*2 p.c. 

 coffein solution. To 200 c.cm. of the mixture 1*4 c.cm. of 0*1 p.c. 

 crystal-violet solution is added. 



In this culture fluid some of the suspected stool is placed, and after 

 24 hours plates are made. 



Demonstrating Typhoid Bacilli in Water.§ — M. Ficker finds that 

 when there are but few typhoid germs in water, the sediment may be 

 enriched by precipitating with iron sulphate. To 2000 c.cm. of the 

 water add 0*8 grm. sodium carbonate and 0*7 grm. sulphate of iron. 

 In about two hours a sediment will have formed. The supernatant 

 fluid is decanted off, and some of the deposit pipetted on to litmus- 

 lactose -agar plates. 



Preparation of Nutrose Agar.||— J. W. H. Eyre gives the following 

 improved method of preparing nutrose agar. This medium was originally 

 devised by Drigalski and Conradi,1T but the author has introduced im- 

 portant modifications. 



A. (1) Emulsify 20 grm. pepton sice. "Witte in 100 c.cm. of dis- 



* Ber. Deutsch. Bot. Gesell., xxi. (1903) pp. 493-8 (1 pi.). 

 t See this Journal, ante, p. 335. 



X Hygien. Rundschau, xiv. (1904) p. 1. § Loc. cit. 



|| Trans. Path. Soc, lv. (1904) pp. 102-3. 

 i See this Journal, 1902, p. 371. 



