PRACTICAL BACTERIOLOGY. 



suitable for photographing ; the ones stained with 

 ordinary aqueous solutions of aniline dyes are too 

 pale, whilst powerful staining reagents, such as pure 

 carbolic fuchsine, and aniline water gentian violet 

 affect the shape of the bacilli. Similarly Gram's 

 method cannot be employed, for the bacteria become 

 changed in form as well as decolourised. In order to 

 demonstrate the flagella, it is necessary to add to the 

 ordinary mordant one drop of the sulphuric acid 

 which is expressly prepared for this purpose. 



The cultivation of the comma bacillus succeeds on 

 all the ordinary nutrient media at ordinary tempera- 

 tures, but especially well at blood heat. Upon gelatine 

 plates kept at a temperature of about 20° C, small 

 white flecks appear, which have not quite clear out- 

 lines, and which when examined with a low power 

 show variously shaped out-growths and slight eleva- 

 tions on their surfaces. Gradually the colonies grow 

 into small greyish-yellow masses, whilst the gelatine 

 becomes slowly liquefied. In puncture cultivations a 

 thin white thread appears after a few days along the 

 track of the needle. This thread suddenly widens 

 out just below the surface, causing a distinct lique- 

 faction and disappearance of the gelatine at this place, 

 whilst a bright glistening bubble of air is drawn into 

 the liquefaction funnel. The whitish thread along the 

 track of the needle broadens somewhat, but never 

 becomes of any considerable size. Gradually the 



