228 BACTERIOLOGY. 



main upon the original medium, it is not uncommon to 

 find the organism incapable of further cultivation after 

 a week or ten days. 



Under no conditions is the growth of this organism 

 very luxuriant. 



On gelatin plates its colonies appear after forty-eight 

 to seventy-two hours as very small, flat, round points, of 

 a bluish-white or opalescent appearance. They do not 

 cause liquefaction of the gelatin, and in size they rarely 

 exceed 0.6-0.8 mm. in diameter. Under low magnify- 

 ing power they have a brownish or yellowish tinge by 

 transmitted light, and are finely granular. As the 

 colonies become older their regular border may become 

 slightly irregular or notched. 



In stab cultures in gelatin they grow along the entire 

 needle-track as a finely granular line, the granules re- 

 presenting minute colonies of the organism. On the 

 surface the growth does not usually extend beyond the 

 point of puncture. 



On agar-agar plates the colonies appear as minute 

 pearly points, which 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 gela- 

 tin slants the growth that results is a -thin, pearly, 

 finely granular layer, consisting of minute colonies 

 growing closely side by side. Its growth is most 

 luxuriant on glycerin agar-agar at the temperature of 

 the incubator (37.5° C), and least on gelatin. 



On blood-serum its colonies present little that is 

 characteristic ; 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 



