Bouillon 547 



Bouillon. In bouillon a diffuse cloudiness was observed by 

 Kitasato, though Yersin observed that the cultures resembled ery- 

 sipelas cocci, and contained zooglea attached to the sides and at 

 the bottom of the tube of nearly clear fluid. 



Fig. 227. Bacillus pestis. Highly virulent culture forty-eight hours 

 old, from the spleen of a rat. Unstained preparation (Kolle and 

 Wassermann) . 



Haffkine* found that when an inoculated bouillon culture is 

 allowed to stand perfectly at rest, on a firm shelf or table, a char- 

 acteristic appearance develops. In from twenty-four to forty- 

 eight hours, the liquid remaining limpid, flakes appear underneath 



^ 



Fig. 228. Bacillus pestis. Involution forms from a pure culture on 3 per 

 cent, sodium chlorid agar-agar. Methylene-blue (Kolle and Wassermann). 



the surface, forming little islands of growth, which in the next 

 twenty-four to forty-eight hours grow into a jungle of long stalactite- 

 like masses, the liquid remaining clear. In from four to six days 

 these islands become still more compact. If the vessels be dis- 



* "Brit. Med. Jour.," June 12, 1897, p. 1461. 



