Vital Resistance 321 



charges in the six cases studied by Weichselbaum and in 

 eighteen studied by Scherer. To determine the presence of 

 the coccus in the nasal discharges where other similar cocci 

 may be present, Gram's stain may be used and followed by 

 an aqueous solution of Bismarck brown. The meningococci 

 will be brown. 



Cultivation. The organism was successfully cultivated 

 by Weichselbaum, but does not readily adapt itself to 

 artificial media. It develops upon agar-agar and glycerin 

 agar-agar, upon LofHer's blood-serum mixture, and, accord- 

 ing to Goldschmidt,* upon potato. Weichselbaum did not 

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

 bouillon or gelatin. 



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 -$ to -f^ of the volume of 

 the agar-agar. It is added to the sterile melted agar-agra, 

 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 

 temperature 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- 



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

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

 21 



