272 ■ BACTERIOLOGY 



perature of 24° C, and gives the best results at incubation 

 heat. On the gelatine plate there form roundish colonies of 

 medium size, and in thrust-cultures little white granules 

 appear along the needle-track, and a slight transparent 

 prominence on the surface. The gelatine is not liquefied. 

 A thin transparent film forms upon agar, and a thin 

 transparent slimy coating upon serum. The cultures do 

 not last very long, and lose their virulence if kept at a 

 temperature of 42° C. even for one or two days. The same 

 result is also attained, according to Frankel, by cultivation 

 in milk. In order to preserve the virulence of the cocci, 

 they must be inoculated from time to time upon animals. 



The diplococci cultivated upon artificial nutrient media 

 show no capsules, and after losing them they become regu- 

 larly round and range themselves in chains, in consequence 

 of which they have been described by Gamaleia as Strepto- 

 coccus lanceolatU'S. They exhibit capsules in the blood of 

 animals infected with the cultures. 



The cocci stain in dilute alcoholic solutions of the 

 aailine dyes, and can easily be displayed in preparations 

 coloured by Gram's method, differing therein from the 

 Pnenmohacillus of Friedliinder. The capsules remain un- 

 stained by the ordinary methods : to colour them Eibbert 

 employs a hot saturated solution of the capsules of dahlia 

 violet in 100 parts water, 50 parts alcohol, and 121 parts 

 acetic acid. Staining takes place very rapidlj' in this 

 solution, and moreover it is necessary to wash in water 

 only for a short time. The cocci appear dark blue, the 

 cai^sules light blue. 



For transmission of pure cultures those on bouillon are 

 the most suitable, and of these one or two cubic centimeters 

 are used as a hypodermic injection. The cocci with their 

 capsules are found in the blood and organs, but subcuta- 

 neous injections fail to set up inflammatorj' symptoms in 



