180 BACTERIOLOGY. 



out into long filaments both in the animal 

 body and in cultures ; they are decolorized by 

 Gram's method. During spore-formation the 

 rods become spindle-shaped ; the bacteria be- 

 long, therefore, to the genus Clostridium. 

 They are anaerobic. In gelatin they grow with 

 vigorous gas-production ; the margin of the 

 colonies is frayed out into fine rays, and the 

 gelatin is gradually liquefied. In agar stab- 

 cultures also the colonies show branching. In 

 bouillon, a turbidity makes its appearance 

 followed by a deposit of sediment. The effect 

 brought about in animals by subcutaneous in- 

 oculation is to be attributed not so much to the 

 growth of the bacteria as to the formation of 

 poison ; only after the death of the host has 

 occurred do the bacteria multiply very much, 

 but then they multiply even in the blood, 

 where a state of affairs similar to that in anthrax 

 may sometimes be observed, although during 

 life the blood is germ-free. Subcutaneous in- 

 oculation in guinea-pigs gives characteristic 

 results : the animals become uneasy, draw 

 themselves together in a heap and cry out at 

 the slightest touch. Mice, rabbits, sheep, 

 goats, horses, swine, dogs, fowls and ducks 

 are also very susceptible. Man is moderately 

 susceptible ; gangrenous emphysema is some- 

 times at least, caused by these bacteria. One 



