Gas and Taint in CheEvSe Curd. 235 



thinner translucent zone extending to the edge. In gelatin stab 

 cultures, the growth along the needle track consists of a series 

 of isolated or confluent grayish colonies which are more numer- 

 ous near the surface. The surface growth is spreading. 



Potato. — A thin brownish yellow growth first appears. After 

 several days jn the incubator it becomes thickened and of a 

 brownish color. It is not viscid. 



Alkaline Bouillon. — At 37.5° C. the liquid becomes uniformly 

 densely clouded with the accumulation of a grayish friable sedi- 

 ment which is easil}^ disseminated upon agitation. The reaction 

 is acid during the period of most active growth, but it becomes 

 alkaline in about five days. At this time the sediment has a 

 floculent or fluffy appearance extending up into the liquid for 

 several millimeters. In old (3 to 6 weeks) cultures a thin, 

 grayish pellicle forms over the surface. 



Acid Bouillon. — The growth is similar but less vigorous in acid 

 than in alkaline bouillon. The sediment is somewhat lumpy or 

 aggregated into dense masses. If undisturbed, a thin pellicle 

 may form on the surface. The reaction finally becomes alkaline. 



Milk. — This organism coagulates milk in about three days, 

 when grown at a temperature of about 37° C. The coagulum 

 contracts apd becomes covered with a clear serum. The casein 

 is not digested. It is strongly acid in reaction and gives off a 

 sour odor. Occasionally the taint similar to that in the curds 

 can be detected in 24 hour cultures. It is, however, more notice- 

 able in larger quantities of milk. 



Gas production as detei^niined i?i the fermentation tubes with 

 bouillon containing sugars, (i) One per cent glucose bouillon — 

 On the day following the inoculation, the liquid in the open bulb 

 is heavily clouded and acid in reaction. In the closed arm, the 

 liquid is less heavilj' clouded. In the bottom of the tube there 

 is a considerable quantit}^ of a grajdsh, friable sediment. Gas 

 is present. The maximum amount of gas is produced b}^ the 

 second day. It occupies y\ of the capacity of the closed arm of 

 the tube. 



, (2) Oiie per cent lactose bouillon. — The liquid in the open arm 

 becomes clouded and acid in reaction in 24 hours. The liquid 

 in the closed arm is more faintly clouded. Gas is present. The 



