62 BACILLUS TYPHOSUS 



apparently vacuolated. This appearance — polar 

 staining — was supposed to be evidence of spore 

 formation, but Buchner has shown that this is not 

 the case. A preparation showing such polar stain- 

 ing with the central " clear space " is represented in 

 Fig. 55, and the resemblance to the appearances 

 presented by true spore formation will be seen. 

 A culture of B. Typhosus examined in a "hang- 

 ing drop " is seen to be actively motile, and is found 

 to owe this motility to the possession of numerous 

 long flagella. Fig. 56 shows these flagella to be 

 many times the length of the bacillus, to be very 

 numerous, and to pass out from all parts of the cell 

 periphery so as to form the so-called " spider cells." 

 The flagella are decidedly more numerous in the 

 case of B. Typhosus than in that of B. Coli, and 

 usually vary from about 10-18. 



With pure cultures of B. Typhosus a fatal disease 

 can be produced in many of the lower animals, 

 though the virulence of the cultures rapidly dis- 

 appears. As a rule, the disease produced is acute 

 and toxic in its character, but recently a chronic 

 disease resembling the enteric fever of man has been 

 produced in rabbits by feeding them on infected 

 food. Against the disease produced by inoculation 

 animals may be immunised. The blood serum of 



