ANTHRAX. 71 



present in pure culture. The growth takes place in 

 lines which project nearly at right angles to the line of 

 inoculation, and grow more vigorously the nearer they 

 are to the surface. The result is the development of 

 a culture which has a strong resemblance to an inverted 

 fir-tree (fig. 14). In another day or two the gelatin 

 will begin to show a certain amount of liquefaction at 

 the surface. 



The appearances in the plate-culture are perhaps not 

 quite so characteristic, but they are manifested in 

 impure cultures. The young colonies of anthrax bacilli 



FIG. 15. Young colony of anthrax bacillus (x 15). (Crookshank). 



have a whorled appearance which has been compared to 

 a barrister's wig or to the head of Medusa (fig. 15). The 

 plate should be placed upon the stage of the microscope 

 and examined for these colonies with the low power. 

 If one is found a clean cover-glass should be pressed 

 upon it, lifted up with a needle so as to bring up the 

 colony with it, fixed by heat, and stained with carbol- 

 thionin or methylene blue. The colonies are most 

 characteristic after two days incubation ; at a later 

 period the gelatin is liquefied and spores are formed. 



