502 C. A. LAUBACH, J. L. RICE AND W. W. FORD 



typical mesentericus spores. They retain definite rims of proto- 

 plasm at times concentrated at one end of the spore and measure 

 0.375 to 0.5 by 1 to 1.25 microns. As they lose their rims of 

 protoplasm they become more oval and measure about 0.75 by 

 1 micron. 



Agar slant. Growth scanty in 24 hours, then becomes slightly 

 raised, finely wrinkled, translucent, non-spreading and viscous. 

 When older the growth has a tendency to become somewhat 

 dry and gray and is easily scraped off. On highly acid agar the 

 growth is more profuse within 24 hours but is not viscous. 



Agar stab. Slight granular growth along the line of inocula- 

 tion with occasionally a slight budding out from the stab. 



Agar colonies. Colonies small, drop-like, slightly irregular, 

 showing little or no tendency to spread, glistening, elevated and 

 viscous. In some cases a scum-like covering which enclosed 

 clear gelatinous material was produced about each colony. 



Glucose litmus agar slant. Moderate non-spreading growth 

 within 24 hours. The surface of the growth has a sort of honey- 

 combed appearance caused by fine interlacing wrinkles. It is 

 also viscous and is somewhat bluish-gray in color. The reac- 

 tion is definitely acid within 24 hours. This acidity is followed 

 by a reduction of the litmus and a gradual return to alkalinity. 



Glucose litmus agar colonies. The colonies correspond closely 

 to those on plain agar but usually attain somewhat greater 

 dimensions. 



Gelatin stab. Rapid funnel-like and progressive liquefaction. 

 Complete liquefaction results with the formation of a tenacious 

 grayish scum. 



Gelatin colonies. The colonies on gelatin plates rest in cup- 

 like excavations caused by rapid liquefaction. A definite brown 

 center with a surrounding grayish granular area is evident in 

 each colony under the low power of the microscope. 



Broth. A slight turbidity is produced within 24 hours with 

 the beginning formation of a scum. The scum later is finely 

 granular and is formed of discrete colonies. The medium clears 

 itself by sedimentation. 



Peptone. Reaction the same as that in broth. 



