130 ATLAS OF BACTERIOLOGY. 



(Ziegler's "Beitrage," XII.). Kutscher lias recently 

 published the experience that a pseudo-glanders 

 bacillus, taken from the animal, had a bright orange- 

 red color only in the first culture upon serum, but 

 this color changed to white after a few inoculations. 

 Perhaps still greater importance attaches to the 

 often made observation that, as the result of in- 

 ternal causes, colored and uncolored colonies of one 

 variety, for example, bacterium kiliense, occasion- 

 ally develop upon plate cultures. 



2. The Formation of Alkaline Metabolic Products and 

 Urea Fermentation. 



According to v. Sommaruga (Z. H., XII., 273) 

 aerobic bacteria, when growing in a non-saccharine 

 nutrient medium, always produce an alkali from the 

 albuminoids. 



When sugar is present the majority of varieties 

 form acid out of the sugar, in addition to the produc- 

 tion of alkali, and the originally neutral or feebly 

 acid reaction of many young bacterial cultures is ex- 

 plained simply by a slight percentage of sugar in the 

 bouillon (derived from the meat) . When the sugar 

 is used up, the production of alkali becomes more 

 pronounced (Th. Smith). 



So far as we know at present, the alkaline bodies 

 produced are ammonia (occasionally perceptible to 

 the sense of smell), amine and ammonia bases. In 

 order to determine the degree of production of the 

 alkali, we titrate tubes which contain 10 c.c. peptone 

 bouillon, uninoculated, and one to eight days after 

 inoculation with one-tenth normal acid and phenol- 



