Vital Resistance 427 



ing to Goldschmidt,* upon potato. Wiechselbaum did not 

 find that it developed upon potato. It does not grow in 

 bouillon or gelatin. The cultures are usually scanty and 

 without characteristic features. 



Flexnerf found that the difficulties of cultivation were 

 greatly reduced by the employment of sheep-serum instead 

 of human serum. Sheep-serum water was prepared accord- 

 ing to the method of Hiss (sheep-serum i part, water 2 

 parts, sterilized in the autoclave) and mixed with a beef- 

 infusion agar-agar containing 2 per cent, of glucose. The 

 quantity of sheep-serum need not exceed 7 V to $ of the vol- 

 ume of the agar-agar. It is added to the sterile melted 

 agar, which is afterward slanted in test-tubes or allowed to 

 congeal on the expanded surface of i6-ounce Blake bottles 

 when mass cultures are to be used. There is nothing charac- 

 teristic about the cultures. The cocci grow only at the tem- 

 perature of the body, attain only a sparse development, 

 and form a more or less confluent line of minute, rounded, 

 grayish colonies which are easily overlooked upon opaque 

 media like blood-serum. The general characteristics of the 

 growth are not unlike those of the pneumococcus, strep- 

 tococcus, and gonococcus. 



Colonies. When grown upon agar-agar plates, the deep 

 colonies scarcely develop at all, appearing under the low- 

 power lens as minute, irregularly rounded granular masses. 

 The surface colonies are larger, and consist of an opaque 

 yellowish-brown nucleus about which a flat, rounded disk 

 spreads out. The edges may be dentate; the color is grayish 

 or yellowish near the center, becoming less intense as the 

 thin edges are reached ; the structure is finely granular. 



Vital Resistance. The vitality of the culture is low, 

 and the cocci die out readily, ceasing to grow when trans- 

 planted after eight or ten days. It becomes necessary, 

 therefore, when studying the organism to transplant it 

 frequently ParkJ says every two days. Flexner found 

 that they do not survive beyond two or three days and that 

 transplantations do not succeed unless considerable quanti- 

 ties of the culture are placed upon the surface of the fresh 

 medium, showing that many of the organisms were already 



* "Centralbl. f. Bakt. u. Parasitenk.," n, 22, 23. 



t "Jour. Experimental Med.," 1907, ix, p. 105. 



| "Bacteriology in Medicine and Surgery," 1899, p. 362. 



Loc. cit. 



