SEPTIC^MIA OF M. TETRAGENUS. 199 



tion a circumscribed white point, slightly elevated above 

 the surface and limited to the immediate neighborhood 

 of the point of inoculation. Down the needle-track 

 the growth is not continuous, but appears in isolated, 

 round, dense white clumps or beads, which do not 

 develop beyond the size of very small points. 

 It does not liquefy gelatin. 



Upon plates of nutrient agar-agar the colonies appear 

 as small, almost transparent, round points, which have 

 about the same color as a drop of egg-albumin; they are 

 very slightly opaque. They are moist and glistening. 

 They rarely develop to an extent exceeding 1 to 2 mm. 

 in diameter. 



Upon agar-agar as stab or slant cultures, the surface 

 growth has more or less of a mucoid appearance. It is 

 moist, glistening, and irregularly outlined. The outline 

 of the growth depends upon the moisture of the agar. 

 It is slightly elevated above the surface of the medium. 

 In contradistinction to the gelatin stab- cultures, the 

 growth is continuous along the track of the needle in 

 the stab cultures upon agar-agar. 



The growth on potato is a thick, irregular, slimy- 

 looking patch. 



The presence of the transparent gelatinous substance 

 which is seen to surround these organisms renders them 

 coherent, so that efforts to take up a portion of a colony 

 from the agar-agar or potato cultures results usually in 

 drawing out fine silky threads consisting of organisms 

 imbedded in this gelatinous material. 



The organism grows best at from 35 C. to 38 C., 

 but can be cultivated at the ordinary room temperature 

 about 20 C. 



The growth under all conditions is not rapid. 



