THE ANTHRAX BACILLUS. 191 



are found, only these long threads, which are twisted 

 together in wavy strands. These strands are some- 

 times quite close together, and sometimes further 

 apart, so that the appearance presented by the colony 

 has been correctly compared with a mass of curly 

 hair ; like natural locks on a curly head, the strands 

 of bacillus threads proceed from the centre to the 

 margin, becoming gradually less dense and entangled 

 as they approach the edge of the mass. 



Liquefaction of the gelatine gradually takes place, 

 commencing in the centre and spreading towards the 

 margin. As the gelatine becomes liquid the colony 

 loses its characteristic appearance, until after a time 

 this is only to be seen at the edges, where the medium 

 is still solid. 



Before the area of liquid gelatine is large, and be- 

 fore the colonies exceed one or two millimetres in 

 diameter, an impression cover-slip preparation should 

 be made in order to preserve this characteristic 

 growth. 



A thoroughly clean cover-glass is taken up with the 

 forceps, and so placed that one edge rests on the 

 gelatine, whilst the rest is held in a slanting direction 

 over a colony ; the glass is then allowed to sink 

 gradually down, care being taken to allow the air 

 which is between it aud the somewhat sunken centre 

 of the colony to escape. It is hardly necessary to 

 press the cover-glass down; it is better to lift it up 



