262 



Hog Cholera. 



it occurs singly or in pairs, in cultures however it also forms 

 longer chains or even slightly curved filaments. 



Staining. "With aqueous aniline dyes the organism usually stains 

 uniformly, sometimes, however when stained with diluted methylene 

 blue solution, it may stain more intensively on the poles. It does not 

 stain by Gram's method. 



B.sTJip 



OljOt 



■^m 



Cultivation, The bacillus grows aerobically as well as 

 anaerobically on all artificial media, in room temperature 

 as well as body temperature; in the latter however con- 

 siderably faster (the temperature limits are according to 

 Frosch +8 and -|-42°C.). On gelatin plates bluish, trans- 

 parent, uniformly rounded colonies de- 

 velop, while in stab cultures a continuous 

 grayish-white streak forms along the stab, 

 surrounding which the nutritive medium 

 is sometimes turbid. Gelatin is not lique- 

 fied (Fig. 48). On agar bluish, trans- 

 parent, flat, round colonies develop which 

 do not closely adhere (Fig. 49) ; the growth 

 on coagulated blood serum is similar. On 

 Loffler's malachite-green plates, and on 

 endo-plates, colorless colonies form, while 

 on DrigalsM's plates the colonies are blu- 

 ish. Peptone bouillon becomes uniformly 

 cloudy, later a loose sediment settles on 

 the bottom of the tube; indol does not 

 form in the cultures. On potatoes a color- 

 less, moist, lustrous, or a brownish-yellow 

 deposit forms (the variance is probably 

 due to the different kinds of potatoes). 

 Milk becomes grayish, in 3 to 4 weeks sa- 

 ponified, and still later it is changed to a 

 stiff, alkaline jelly. Litmus milk is some- 

 what reddened, but after 2 to 4 days it be- 

 comes decidedly bluish. Dextrose is fer- 

 mented by the bacillus, lactose on the other 

 hand is not. 



Tenacity. The cholera bacillus withstands 

 simple drying for four months, but in the in- 

 fluence of sunlight and by alternate drying and 

 moistening it is quickly killed. In ordinary drink- 

 ing water, also in soil infected with feces of 

 affected animals, it retains its virulence for 65 

 to 95 days, while a temperature of 50° destroys it 

 in 66 hours, and one of 55° in one hour (Preisz). 

 Of the disinfectants the growth of the bacillus in inhibited by 1:4000 sulphuric 

 acid, 1:900 potassium hydrate ; it is destroyed in one minute by a 1% carbolic acid, 

 solution, 1:10,000 corrosive sublimate, 1% creolin, in 10 minutes by 1% milk 

 of lime, in three minutes by a 1% copper sulphate solution, in 1% minutes by 0.1% 

 formalin solution, and in three hours by a 2% iron sulphate solution (Koppanyi & 

 Erdos). The bacillus suipestifer is considerably more resistant than the bacillus 

 suiseptieus. 



Pathogenicity. Mice are susceptible to artificial infections, 

 and after an inoculation with 0.1 mg. of bouillon culture they die 

 of septicemia in from 3 to 5 days. The guinea pig and rabbit 



Fig. 48. Four 

 day old gelatin 

 stab culture of 

 the iaoillus 



Fig. 49. Two- 

 day old agar 

 culture of the 

 hacillus sui' 



