152 A MANUAL OF BACTERIOLOGY 



means groups of bacilli become planted at a con- 

 siderable distance from each other (Fig. 36). This 

 appearance is quite characteristic of B. alvei, and is 

 not seen in the cultivation of any other microbe. 

 'The bacilli of anthrax and of mouse septicaemia 

 also spread out from the needle track, but the 

 appearance of their cultivation is quite different. 

 In anthrax delicate threads, not clubbed, shoot out 

 from the track, soon anastomosing with other 

 threads and forming a delicate network throughout 

 the gelatine. In mouse septicaemia the appearance 

 is that of a delicate cloudiness spreading through 

 the gelatine. These ' foul-brood ' bacilli, growing in 

 this material, render it liquid after a time, the 

 liquefaction beginning at the surface and only 

 spreading slowly downwards, but ultimately the 

 whole tube becomes liquid. The liquid becomes 

 yellowish in colour after a time, and gives off an 

 odour of stale, but not ammoniacal, urine. This 

 colour and odour are distinctive of the diseased 

 larvae.' 



In plate- cultivations, the bacilli grow out in 

 series of rods in single file, or in rows of several 

 side by side. The processes which are formed have 

 a tendency to form curves and circles. Later on, 

 the gelatine in the vicinity of the bacilli becoming 

 liquid, forms a series of channels in which the 

 bacilli move backwards and forwards. 



They grow most rapidly on the surface of nutrient 

 agar-agar, forming a whitish layer, but the ramify- 

 ing processes seen on the surface of gelatine do 

 not occur, or only very imperfectly, in agar-agar. 



