'236 



BACILLI PATHOGENIC IN MAN. 



Growth on 



gelatine 



plates. 



seeds of plants containing starch, on juicy roots ; they 

 may also be cultivated and form spores at a suitable 

 temperature in alkaline urine, in neutralised hay infu- 

 sion, in meat infusion. They belong to the aerobes, in 

 so far that they only grow imperfectly when oxygen is 

 excluded ; attention must also be paid in cultivations to 

 the great sensitiveness of the anthrax bacilli to an excess 

 of acid in the nutrient substrata. In plates of nutrient 

 jelly they form after 24 to 36 hours small scarcely visible 

 points; under a low power, however, a characteristic 

 appearance can be seen at this stage ; the round, dark, 

 greenish-black colonies have an irregular wavy contour. 



Fig. G4. -Anthrax colony in gelatine. 

 a, after 24 hours. b, after 48 hours X 80. 



This wavy margin becomes more and more marked as 

 the growth of the colony increases, and at once becomes 

 much more distinct and spreads out more quickly on all 

 sides when the colony has reached the surface of the gela- 

 tine. Under a low power the dark remnant of the deeply 

 placed colony can only be seen in the middle ; around 

 this centre, however, there is a light-brown or light-grey 

 shiny mass, which consists of numerous wavy, curly 

 bundles, recalling the appearance of the locks of hair on 



