282 BAQTERIOLOGY. 



On agar-agar plates the colonies appear as minute 

 pearly points, M'hich when slightly magnified are seen 

 to be finely granular, of a light-brownish color, and 

 regular at their margins. 



When smeared upon the surface of agar-agar or gel- 

 atin slants the growth that results is a thin, pearly, 

 finely granular layer, consisting of minute colonies 

 growing closely side by side. Its most luxuriant 

 growth is seen on glycerin-agar-agar at the tempera- 

 ture 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 char- 

 acteristic ; they appear as small, moist, whitish points, 

 from 0.6 to 0.8 mm. in diameter, that are slightly ele- 

 vated 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 inocula- 

 tion, and microscopic examination shows that multiplica- 

 tion of the organisms placed at this point has occurred. 



In milk its conduct is not always the same, some cult- 

 ures 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 37.5° C. 



In bouillon it grows as tangled masses or clumps, 

 which upon microscopic examination are secMi to ccmsist 

 of long chains of cocci twisted or matted together. 



