198 BACTERIOLOG Y 



Gram's method ; but the simplest mode of recognising them 

 in pus consists in examining the little yellow globular bodies 

 without staining (figs. 73 and 74). 



Cultivations on glycerine agar show, according to 

 Protopopoff and Hammer, a mass of closely-packed miliary 

 nodules of the size of hemp-seed at largest, which have a 

 yellow colour and adhere very firmly to the medium. The 

 growth on potato is similar, except that the culture looks 

 quite dry. In broth miliary nodules develop after a short 

 time, and may attain the size of a hazel-nut. Gelatine is 

 slowly liquefied. Growth takes place also in the absence of 

 oxygen, in eggs, by Hueppe's method. 





t 





Fig. 74.— Actinomyces, stained by Gram's Method. (After Jakscli.) 



P. Winkler has cultivated actinomyces on plover's egg 

 albumen in the author's Institute. Formation of sulphur- 

 yellow colonies as large as poppy-seeds takes place all over 

 the surface of the medium, which is, however, not liquefied. 



Bacillus pyocyaneus. — This bacillus is the cause of the 

 grey or blue colour sometimes seen in pus and in pieces of 

 dressing saturated with it. 



The Bacillus pyocyaneus a, described by Gessard, consists 

 of small slender rods provided with a flagellum, by means of 

 which they move swiftly. Upon gelatine plates roundish 

 islets of a yellow colour appear in the substance of the 

 medium,'to the whole of which they impart a greenish tint 

 in about two days, 'causing at the same time slow lique- 



