18971 MICROSCOPICAL JOURNAL. 159 



MICROSCOPICAL MANLPULATION. 



A New Culture Medium for the Diphtheria Bacillus. — 

 Joos (Jour. Med. de Bruxelles, May 7, 189G) has had occa- 

 sion to make alarge number of bacteriolog-ical examinations 

 in cases of suspected diphtheria. He finds that the ordi- 

 nary methods of cultivating- Loffler's bacillus are not sat- 

 isfactory; he also finds Deycke's method unsatisfactory, 

 as it hinders the g-rowth of the Loftier bacillus, and stunts 

 the colonies. Joos has modified Deycke's medium, and 

 claims to have found a material on which no other bacillus 

 except that of diphtheria will g-row normally. He pre- 

 pares "albuminate of soda" by adding- satiirated caustic 

 soda solution to serum of strong- alkalinity, placing- the 

 mixture in a vapor bath for half an hour, and filtering-. 

 To the filtrate is added pure hydrochloric acid till the re- 

 action is neutral or very slightly alkaline. If too much 

 caustic soda was not added at first, the substance is now 

 ready for use; otherwise the excess of sodium chlorid re- 

 quires to be dialyzed out. On evaporating- to dryness, a 

 powder is obtained which is readily soluble in water, and 

 which is not coag-ulated by heat. The nutritive medium 

 is prepared by adding- to 1000 g-r. of peptonized bouillon 20 

 g-r. each of agar and "albuminate of soda." The mixture 

 is placed in the autoclave at a temperature of 115 deg-rees 

 to 120 deg-rees C. for half an hour; then 15 c.cm. of caustic 

 soda are added, and the whole put back in the autoclave 

 for fifteen minutes, after which it is filtered in the vapor 

 bath. After filtration, it is sterilized at 120 deg-rees C. in 

 the autoclave for three quarters of an hour, when it is 

 ready for the preparation of the plates. It is claimed by 

 Joos that streptococci will not g-row on this medium at all, 

 and staphylococci but feebly, while Loffler's bacillus grows 

 luxuriantly in from six to twelve hours. If the presence 

 of streptococci is to be determined as well, the amount of 

 "albuminate" is to be reduced to one and one-half ])er cent. 

 At the end of fifteen to eighteen hours small colonies of 

 streptococci may be seen among- the larg-e and well-devel- 

 oped patches produced by the diphtheria bacillus. 



