BACILLUS OF SOFT CHANCRE 163 



themselves. Old cultures are poisonous ; a haemolysin is produced 

 an endo-toxin, and a soluble toxin. Against the endo-toxin and the 

 soluble toxin it is possible to prepare an anti-serum. This may pro- 

 tect laboratory animals. The last named toxin stands a tempera- 

 ture of 100 C. 



Pathogenesis. Has been found a sole cause of meningitis and 

 vegetative endocarditis in man; is a pyogenic organism; can cause 

 suppuration anywhere in the body; produces blue pus; is pathogenic 

 to guinea pigs; and its virulence can be raised by passing it through 

 a series of animals. 



Agglutination. The serum of infected and immunized animals 

 both in moderate dilution causes agglutination of bacilli. It is 

 possible to use bacterins of this germ. Bactericidal substances 

 develop by the use of killed cultures. 



BACILLUS OF SOFT CHANCRE. 



Bacterium Ulceris Chancrosi. (Ducrey.) 



Streptobacillus of Soft Chancre. 



Morphology and Stains. A small thin bacterium .5/1 broad, 

 1.5^ long, growing in chains with polar staining, which can be 

 demonstrated in sections of chancres without much difficulty. 



This organism does not stain by Gram's method, but by Lo filer's 

 it is stained with ease. 



Cultures are hard to make. It grows best in serum agar, and 

 blood agar in faint colonies that are not very characteristic. In 

 condensation water of agar it grows feebly. 



In sections and in pus the organism is frequently found in the 

 interior of leucocytes. 



By aspirating pus from buboes and planting it in blood agar 

 cultures may be obtained. 



Pathogenesis. From an old culture of over ten generations 

 typical ulcerations were produced in man. The organism is feeble 

 and quickly dies in culture media or in contact with mild antiseptics. 



