ZOOLOGY AND BOTANY, MICROSCOPY, ETC 10.> 



not kill the bacilli : this specific property can he used to identify 



B. typhosus from other allied bacilli. 



Achromogenic Cultures of Micrococcus prodigiosus.*— M. Cordier, 

 H. Rajat, and G. Peju placed open agar-tube cultures of Bacillus pro- 

 digiosus in a 150 c.cm. flask tilled to one-third with sulphuric ether ; a 

 glass vessel, part full of cotton wool, was inverted over the whole, 

 covering at the same time the opening of the culture tube and of tin 

 flask ; after standing in the dark, at the temperature of the laboratory. 

 growth slowly appears, but of a white porcelain aspect, and showing no- 

 trace of pigment. A control tube, inclosed in a similar flask containing 

 water, showed typical pigmented cultures. 



If the achromogenic cultures are transferred to fresh media, the- 

 subcultures are also free from pigment, but after a few generations tin 

 red colour reappears. The author finds that the longer the duration 

 of cultivation in ether vapour, the slower is the reappearance of pig- 

 ment in subcultures ; but a true achromogenic variety cannot be 

 permanently obtained. Similar results were observed by substituting 

 ethyl- or methyl-alcohol, chloroform and xylol for ether. 



Blood Cultures.f — Lafforgue adopts the following procedure for 

 blood cultures. The blood is obtained by venous puncture and mixed 

 with citrate of soda : one drop (5^ c.cm.) of 20 p.c. citrate solution to 

 1 c.cm. of blood. The mixture is centrifuged and the supernatant 

 liquid decanted, and the deposit is distributed into flasks or tubes of 

 broth. The removal of the serum, which contains comparatively very 

 few germs, is not likely to cause serious error, and at the same time its 

 slightly inhibiting action is also removed. 



The method is economical, and permits the transmission of blood 

 specimens, without any liability to interfere with subsequent bacterio- 

 logical investigation. 



Action of Meningococcus and similar organisms on Sugar Media. % 



C. Dopter and Raymond Koch employ the following media for studying 

 the action of meningococcus and allied organisms in various sugars. To* 

 75 c.cm. of slightly alkaline agar is added 1 grm. of lrevulose, dextrose,. 

 or maltose, etc. ; after sterilisation there are added 25 c.cm. of ascitic 

 fluid, and 1 c.cm. of sterile 1 p.c. solution of neutral red ; the mixture- 

 has an orange tint, and is kept in a water-bath at 60° C. for 1 hour, 

 until the formation of a fine precipitate of neutral red occurs. The 

 medium is then poured into Petri dishes — it has a yellowish tint in thin 

 layer — and cultures are made for meningococcus, pseudo-meningococcns, 

 and gonococcus, and incubated at 37° C. 



The authors find that meningococcus, after 2-4 hours on dextrose and 

 maltose, gave a carmin-red colour ; on laevulose and other sugars no- 

 fermentation occurs. The coccus catarrhalis is without action on any 

 sugar. Flavus i. and ii. ferment laevulose, dextrose, and maltose, bnt 

 Flavus iii. has the same reactions as meningococcus. 



Diplococcus crassus {Pseudomeningococcus Jaeger) ferments most all 

 the sugars. Gonococcus only ferments dextrose. 



* C.R. Soc. Biol. Paris, lxv. (1908) p. 344. 

 t Tom. cit., p. 340. X Tom cit., p. 351. 



