368 SUMMARY OF CURRENT RESEARCHES RELATING TO 



H 2 S0 4 (phenolphthalein being used as the indicator) retard or even 

 prevent the colour change ; further, that under certain cultural condi- 

 tions B. typhosus can produce colour reactions similar to those regarded 

 as peculiar to the B. coll. The authors finally propose as a means of 

 differentiating the B. typhosus from the B. coli, the use of a bouillon 

 containing 3 or 4 p.c. lactose and coloured by the addition of • 5 p.c. 

 of a 1 p.c. watery solution of neutral red (Grubler). The reaction of 

 this medium does not require to be accurately standardised, although a 

 reaction corresponding to 1 p.c. H 2 S0 4 appears to give the best results. 

 In such a medium the B. typhosus produces a yellow colour within 4 to 

 6 days, whilst the B. coli produces a red coloration, and no further change 

 takes place even after the lapse of considerable periods. 



Enrichment Method for Typhoid Bacilli.* — The method described 

 by E. Altschuler depends on the specific agglutination reaction. The 

 first step is to incubate the suspected water at 37° for 24 hours in a 

 medium containing 1 p.c. peptone and 0*5 p.c. common salt. Then 

 10 c.cm. are pipetted into a burette, the lower end of which is fitted 

 with a piece of rubber tubing and a clip. To the 10 c.cm is then added 

 immunised serum, and after about 7 hours the precipitate is passed into 

 another tube which contains pepton-salt solution and a few sand-grains. 

 This second tube, half the size of the former, is fitted at both ends 

 with a piece of rubber tubing and a clamp. After an incubation of 

 24 hours it will be found that the typhoid germs have much increased 

 in number. 



(2) Preparing Objects. 



Ether as a Narcotising Medium for Aquatic Animals.t — Hjalmar 

 Ostergren advocates the virtues of ether-water for narcotising marine or 

 fresh-water animals. By means of vigorous shaking in a tightly corked 

 bottle, 2 parts of ether to 25 of water (sea or fresh) an almost saturated 

 solution of ether (7-8 p.c.) is obtained. This solution can of course be 

 diluted to any desired extent, and as each kind of animal differs as to its 

 susceptibility for ether it is advisable to begin with low strengths and 

 work up to higher grades. Certain animals should be previously treated 

 with magnesium sulphate or chloride by Tullberg's method .% Others 

 which are not influenced by the magnesium salts may be treated with 

 good result by the following device. The animals are placed in a tall 

 vessel containing their natural water. The strong ether mixture is then 

 poured carefully over the surface and the two layers are gradually mixed 

 by stirring the fluids together at longer or shorter intervals. If neces- 

 sary more strong ether solution may be added or even 95 p.c. alcohol. 



Of course the narcotising operations should be carried out in closed 

 vessels. 



Demonstrating the Structure of Gastropods. § — G. Mazzarelli 

 places the living larvas in a test-tube containing some sea water and then 



* Ontralbl. Bakt., 1" Abt. Orig. xxxiii. (1903) pp. 741-3 (1 fig.). 



t Zeiti-chr. wiss. Mikr., xix. (1903) pp. 300-8. 



\ See this Journal, 1S92, p. 435. 



§ Kend. R. Istit. Lombardo, xxxv. (1902) pp. 719-20. 



