METHODS OP INVESTIGATING BACTERIA. 785 



on the other hand, typhoid hacilli and cholera spirilla are 

 decolourised by the iodine solution. 



Buchner,* and subsequently Hueppe, was the first staining of 



, , . . . . ,, f . the spores of 



who was successful in staining the spores of various bacilli, 

 bacilli. In order to stain the spores the cover glass 

 preparations are raised to a higher temperature than in 

 staining the bacteria, thus they are not passed three times 

 but from six to ten times through the flame, or they are 

 kept for a quarter to half an hour in a dry chamber at a tem- 

 perature of 180 to 200 C. After this treatment the spores 

 take up the ordinary aniline dyes. Neisser, however, suc- 

 ceeded in staining spores by the use of the solutions 

 employed to stain tubercle bacilli when they were at the 

 same time warmed. Cover glass preparations, prepared 

 in the ordinary manner, are floated on the aniline fuchsine 

 solution at a temperature of 80 to 90 C. for ten, twenty, 

 or even forty minutes, and are subsequently treated like 

 preparations of tubercle bacilli. By this method the 

 spores are stained red and the bacilli blue. 



In order to preserve the preparations we can employ Preservation 

 Canada balsam, dammar, a concentrated solution of aration. e ~ 

 acetate of potash or glycerine ; the latter, however, is 

 only suitable for preparations stained with solutions of 

 aniline brown which contain glycerine. The best mount- 

 ing material for mould and yeast fungi is glycerine gela- 

 tine (one part of gelatine, six parts of water, seven parts 

 of glycerine, and one part of carbolic acid, warmed and 

 filtered). 



For the examination of the preparations only the best Microscopical 



.,17 T ,-, f .-, , investigation. 



microscopes are suitable. In the case of the larger 

 forms of bacteria for example, anthrax bacilli dry 

 lenses are sufficient, in the case of all the smaller forms 

 it is necessary to use the best oil immersion lenses. t 

 In order to be able to recognise the stained bacteria in 

 the tissue a special mode of illumination is necessary. 



* Miinchener cirzll. Intelligenzbl., 1884, p. 370. 



t Excellent oil immersion lenses and apparatus for illumination are 

 furnished by Zeiss of Jena, Seibert and Kraft, Leitz and R. Winkel 

 in Gottingen. Winkel's lenses are excellent, and, according to the 

 author's experience, are most worth the money. Colouring materials 

 and other apparatus can be obtained from Dr. Griibler in Leipzig. 



50 



