54 Bacterial f3liyht of Pear Blossoms hi South Africa 



Cullural Characters. 



Nutrient agar colonies are evident on the second and attain a diameter 

 of 2 — 3 mm. by the fourth or fifth day. They are white and granidar, 

 or cloudy with a sharply defined white centre; the margins are entire 

 or slightly wavy. Submerged colonies are opaque, yellowish-white, 

 lenticular. 



Nutrient agar stab. Growth takes place along the entire length. 



Nutrienl agar streak. In 24 hours there is a moderate opalescent 

 growth which spreads slowly. It is finally white, wet-shining, thin 

 along the middle, heavier along the sides, margins wavy, eventually 

 spreading over the surface of the slant. More rapid growth is induced 

 by the addition of the agar of 2 % saccharose, dextrose or maltose or 

 5 % glycerine. The water of condensation becomes turbid, but the 

 growth is not viscid. 



Nutrient gelatine colonies are very slow growing, only appearing 

 after 3 — 5 days. The surface colonies are round, slightly raised, entire, 

 buried colonies spherical, granular. The medium is liquefied very 

 slowly. 



Nutrient gelatine stab. Growth is at first filiform, and is slow and 

 feeble ; surface growth spreading with irregular margin ; slow crateri- 

 form liquefaction takes place, later becoming stratiform. 



Nutrient bouillon is clouded after 24 hours and this is accompanied 

 by a slight acidity ; after 48 hours there is greater cloudiness with more 

 or less persistent flocculi, the medium becoming alkaline, and in time 

 showing a tendency to clear. In sugar-free bouillon the liquid remains 

 clear for 24 hours except for a slight sediment. It is neutral at first, 

 becoming cloudy and alkaline after some days. The clouding is never 

 very heavy as compared with other organisms. 



Milk is coagulated in 3 — 4 days ; coagulation is followed by digestion 

 to a pasty or sub-gelatinous condition, with separation of supernatant 

 whey; this is at first acid, later becoming slightly alkaline. Litmus 

 milk is unchanged. 



Blood serum. On this medium the growth is similar to that on 

 nutrient agar; there is no liquefaction. 



Potato, carrot, turnif, beet. There is good growth on all these media ; 

 it is best on beet, weakest on turnip. In all alike a wet-shining white 

 streak forms along the line of inoculation ; the liquid is heavily clouded, 

 white and nearly opaque. The tissues are not softened and there is 

 no odour, gas or pigment. 



