340 APPLICATION OF METHODS OF BACTERIOLOGY 



agar at the temperature of the body (37.5 C.), and its 

 least on gelatin at from 18 to 20 C. 



On blood-serum its colonies present little that is character- 

 istic; they appear as small, moist, whitish points, from 0.6 

 to 0.8 mm. in diameter, that are slightly elevated above the 

 surface of the serum. They do not coalesce to form a layer 

 over the surface, but remain as isolated colonies. 



On potato no visible development appears, but after a 

 short time (thirty-six to seventy-two hours) there is a slight 

 increase of moisture about the point of inoculation, and 

 microscopic examination shows that multiplication of the 

 organisms placed at this point has occurred. 



In milk its conduct is not always the same, some cultures 

 causing a separation of the milk into a firm clot and colorless 

 whey, while others do not produce this coagulation. The 

 latter, when cultivated in milk of a neutral or slightly 

 alkaline reaction, to which a few drops of litmus tincture 

 have been added, produce, as a rule, only a very faint pink 

 color after twenty-four hours at 37 C. 



In bouillon it grows as tangled masses or clumps, which 

 upon microscopic examination are seen to consist of long 

 chains of cocci twisted or matted together. 



It grows best at the temperature of the body (37.5 C.), 

 though development does occur at the ordinary room-tem- 

 perature. 



It is a facultative anaerobe. 



It stains with the ordinary aniline dyes, and is not decolor- 

 ized when subjected to Gram's method. 



It is not motile. Under artificial conditions we have no 

 reason to believe that it enters a stage in which its resis- 

 tance to detrimental agencies is increased. In the tissues 

 of the body, however, it appears to possess marked vitality, 



