l82 BACTERIA 



the line of inoculation, coloring the gelatine greenish-blue, and a 

 white crumbly deposit forms in the bottom of the stab. On agar 

 plates it produces yellowish-white colonies, surrounded by a zone 

 of bluish-green fluorescence. It grows luxuriantly. In agar 

 tubes it multiplies rapidly, spreading over the medium, with 

 wavy thickened edges. The agar quickly turns a dark greenish- 

 blue, and in old cultures the growth changes from yellow to 

 greenish-blue. 



In bouillon it is very dense and yellowish-green; a pellicle forms 

 on the surface, and a sediment is deposited. In old bouillon cul- 

 tures the bacilli undergo autolysis and disappear. In milk the 

 growth is luxuriant, the casein is coagulated, and the clot is ulti- 

 mately digested. The reaction is alkaline. On potato it varies in 

 luxuriance, often being slightly elevated, yellowish,turning to green. 

 The variance in growth is due to the kind of potato used. Drying 

 kills the organism speedily; four hours in sunlight also destroys it. 



Chemical Activities. No gas is generated. Besides the pig- 

 ments (already specified) ammonia is produced, also a peculiar 

 enzyme called pyocyanase by Emmerich and Lowe, which not 

 only digests gelatine and milk curd, but its own and other bac- 

 terial cells as well. Old cultures are poisonous; a haemolysin is 

 produced an endo-toxin, and a soluble toxin. The last-named 

 toxin stands a temperature of iooC. Against the endo-toxin 

 and the soluble toxin it is possible to prepare an anti-serum. This 

 may protect laboratory animals. 



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 patho- 

 genic 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. 



