15ACILLUS OF ANTHRAX 167 



twenty- four hours. On the gelatine plate little white dots 

 appear in a day or two, and rapidly liquefy the medium, 

 floating about on the fluid mass. The colonies are seen 

 under the microscope to consist of irregularly arranged 

 filaments, an appearance which is particularly marked at 

 the border of the colony, and has been compared to the 

 Medusa's head (fig. 64). Impression preparations of super- 

 ficial colonies show the shoots and processes very distinctly. 

 Agar plates after twenty-four hours at incubating tempera- 

 ture show similar figures to those on gelatine. A liquefaction 

 beginning at the surface is seen in thrust -cultures, while 



" -,'.\ , '',!? Fibrous processes at 



fitftf ijto^ir^ the margin 



XKsf/^M 



Hair-like arrange- 

 ment of fibres 



PlG. 64. COLOXY OF THE ANTHRAX BACILLUS OX A GELATINE PLATE, UESEMBLIXtt 

 TIJESSES OF HAIR (THIRD DAY). 



from the inoculated track delicate filaments push out into 

 the gelatine (fig. 65). When liquefaction is further ad- 

 vanced the bacilli sink to the bottom of the funnel-shaped 

 excavation, but no skin forms on the surface, and from the 

 deepest parts of the liquefied area processes push into 

 the still solid gelatine. Superficial cultures on agar 

 form a layer which can be easily raised with the platinum 

 needle. Serum is slowly liquefied, and a dry white coating 

 develops on potato, with considerable formation of spores. 

 Disinfected silk threads are often saturated with such 

 spores, dried, and kept for experimental purposes. 



