256 SUMMARY OF CURRENT RESEARCHES RELATING TO 



B. Technique.* 

 (1) Collecting- Objects, including: Culture Processes. 



Media for Detection of Bacillus coli in Drinking-water.f — 

 G-. E. Gage finds that lactose-neutral-red broth is a good means of 

 making presumptive tests for Bacillus coli in drinking-water, but the 

 test must be limited ; the author's results are based on a reaction which 

 calls for 25-80 p.c. gas formation with reduction of the neutral-red, 

 three days being allowed for a complete reaction. 



The bile-salt broth of MacConkey and Hill gives a reaction in a 

 shorter time, but not so readily when only a few colon bacilli are present. 

 Smith's solution of ordinary broth with 1 p.c. dextrose does not give 

 such uniform results, and does not exclude organisms which have 

 the power to ferment glucose. In using Bndo's medium, forty-eight 

 hours must be allowed for a complete reaction ; a pink or light red 

 coloration is not sufficient ; if in forty-eight hours dark red colonies 

 show up, B. coli may be assumed to be present. Lactose-iitmus-agar is 

 not very useful for plating the organisms, since it does not react readily 

 to the smaller traces of acid produced by different strains of the colon 

 bacillus. 



Filtration of Agar through Glass-wool.} — Th. Porodko finds that 

 the velocity of filtration of agar solution through glass-wool is greater 

 than through filter paper, and that the transparency of the solution is 

 80-90 p.c. greater : but for the thin layers generally used in plates 

 and tubes this difference of transparency is not appreciable. 



Simple Medium for Gonococcus.§ — Piorkowski states that on a 

 medium of the following composition, gonococcus grows well and keeps 

 alive for 8 to 12 days, and further mentions that pneumococcus and 

 meningococcus thrive therein: — To a litre of fresh milk are added 

 5 c.cm. of dilute hydrochloric acid (1 : 4), and incubated at 37° C. until 

 all the casein has precipitated (16 to 20 hours). Or instead of this the 

 milk may be boiled. The filtrate is neutralised with 10 p.c. soda solu- 

 tion and then boiled in a steam bath for a couple of hours, after which 

 it is neutralised again and filtered. The medium is now distributed 

 into flasks or test-tubes and sterilised at 100° C. for one hour. With 

 this stock a fluid medium may be made by mixing with equal bulk of 

 broth or a solid medium with agar (1 : 2). 



Should any casein subsequently separate out from the stock, the 

 supernatant clear fluid should be teemed off and mixed with broth or 

 with agar liquefied at from 40-50° C. 



Cultivating Amoebae and Anguillulae for Class Work.[| — A. Le 

 Dantec obtains amcebse by tearing up pieces of moss by the roots and 



cesses : 



This subdivision contains (1) Collecting Objects, including Culture Pro- 

 mos ; (2) Preparing Objects ; (3) Cutting, including Imbedding and Microtomes ; 



(4) Staining and Injecting ; (5) Mounting, including slides, preservative fluids, etc. ; 



(6) Miscellaneous. ^ 



t Centralbl. Bakt. lte Abt. Orig., xlviii. (1908) p. 280. 

 % Op. cit., 2te Abt. Orig,, xxi. (1908) p. 424. 

 § Miincbener Med. Wochenschr., 1908, p. 735. 

 || C.R. Soc. Biol. Paris, lxvi. (1909) p. 237-8. 



