664 SUMMARY OF CURRENT RESEARCHES RELATING TO 



animal body is capable of producing nerve -fibres in the artificial 

 medium. They give illustrations which support their view. 



Omission of Peptone in ordinary Cultivation Media.* — 0. Nicolle 

 strenuously advocates the omission of peptone from ordinary cultivation 

 media, declaring that its presence is not only useless, but deceitful. In 

 regard to cultures intended for inoculation purposes, he asks : " What is the 

 use of infecting with the organism a sul)Stance which is in itself toxic ? " 



Diagnosis of Bacillus diphtherige, Klebs-Loeffler, and Hoffmann's 

 Bacillus. f — E. Cathoire recommends Rothe's medium, agar or ox-serum, 

 which liave been saccharated and tinted with litmus. Two sugars, 

 dextrose and saccharose, suffice for differentiation. Hoffmann's bacillus 

 vel pseudodiphtheria l)acillus ferments neither, while the Klebs-Loeflfler 

 alters the colour of the litmus-glucose medium very distinctly, and but 

 little affects the saccharose medium. The author points out tliat Hoff- 

 mann's bacillus may often be found in the throats of healthy persons ; 

 it is rarely found in the course of diphtheria, though during con- 

 valescence it is frequently present. This explains why some observers 

 advocate a morphological and physiological transfonnation. These two 

 species retain their cultural characters when subcultivated every week 

 for a year, even after passages in collodion sacs inserted in the peritoneal 

 cavity of guinea-pigs. 



C4) Staining- and Injecting-. 



Demonstrating the Nucleus of Bacteria. $ — J. R. Douglas and 

 A. Distaso point out that in order to demonstrate the presence of the 

 bacterial nucleus, very young cultures must be used. In the case of a 

 spore-forming organism, such as anthrax, they start by taking an old 

 culture rich in spores and make a suspension of this in saline. By cen- 

 trif uging this an emulsion is obtained consisting only of spores. 20 com. 

 of this emulsion with 2 c.cm. bouillon are placed m very strong tubes, 

 and after incubation periods of I, -i, 1, 2, 12 hours, and so on, the tubes 

 are centrifuged until all the bacteria are sedimented. The supernatant 

 fluid is then pipetted off and tlie deposit is mixed with an equal bulk 

 of sterilized serum. From this, presumably, films are made ; anyway 

 the material is fixed in 2 p.c. osmic acid, to which a few drops of glacial 

 acetic acid have been added. After an exposure to the vapour of the 

 fixative for two or three minutes, the preparations are air-dried. They 

 are then stained with Giemsa (1-2 drops to the cubic centimetre of 

 water) for from 4-24 hours or longer. Differentiation, which must be 

 watched under the Microscope, is carried out with 10-20 p.c. alcohol. 

 In successful preparations the cytoplasm is blue and the nucleus red. 

 With organisms which do not form spores good results are difficult to 

 obtain, but the following method is successful. An emulsion, e.g. 

 cholera or typhoid, is made with an equal bulk of human fresh serum, 

 and then incubated for five or six hours. By centrifuging this a small 

 number of bacteria is obtained. An emulsion is then made with a small 



* C.R. Soc. Biol. Paris, Ixxiii. (1912) p. 403. 



t C.R. Soc. Biol. Paris, Ixxiii. (1912) pp. 405-7. 



X Centralbl. Bakt., Ite Abt. Orig., Ixvi. (1912) pp. 321-7. 



