222 



INFECTIVE DISEASES. 



The inoculated tubes are placed in the incubator. In a few hours 

 a whitish turbidity spreads out from the piece of tissue, and upwards 

 in the needle track. Examined microscopically, the turbidity is found 

 to be due solely to the development of the bacilli of oedema. The 

 surface exposed to the air exhibits no trace of the bacilli. To 

 investigate the tubes microscopically, a sterilised glass tube with a 

 capillary end may be used, with its neck 

 plugged with sterilised cotton- wool, and 

 provided at the mouth w r ith a suction ball. 

 The capillary end is thrust into the cultiva- 

 tion, and a small fragment removed by 

 aspiration. 



In the course of the first day the bacilli 

 spread throughout a great part of the 

 agar-agar in such a way that a more or less 

 equally diffused cloudiness of the medium en- 

 sues, with subsequent appearance of strongly 

 marked clouds or lines of turbidity. At the 

 same time gas- bubbles develop along the 

 needle track, and a collection of liquid takes 

 place, while spore-formation also commences. 

 The following day these appearances are more 

 marked, the opacity is more pronounced, the 

 development of gas increases, and the liquid 

 contains more spore-forming bacilli and nu- 

 merous free-spores. 



The nutrient-gelatine cultures during the 

 first day show no macroscopic change, but 



FIG. 104. PURE-CULTURE after a few days the piece of tissue is sur- 

 OF BACILLUS OF MALIG- rounded with a white halo. This gradually 

 NANT (EDEMA IN GRAPE- spreads in all directions, and is apparently 

 SUGAR GELATINE (FRAN- \ 



KEL and PFEIFFER). beset with hairs. I he gelatine liquefies, and 



the fragment of tissue, degenerated bacilli, 



and spores, sink to the bottom. The cultivation is also very 

 characteristic in a | per cent, nutrient agar-agar. If placed in 

 the incubator, in a few hours a cloudiness forms around the piece of 

 embedded tissue, which is caused by bacilli gradually spreading in all 

 directions in the nutrient medium. Mice inoculated from these 

 cultivations die more quickly than from the original infection from 

 dust. On potatoes they are cultivated by introducing a piece of liver 

 or other tissue containing the bacilli, into the interior of a sterilised 

 potato, and incubated at 38 C. The bacillus is not deprived of its 

 virulence by cultivation. 



