368 



BACILLI WHICH CAUSE FERMENTATION. 



Anaerobic 

 properties. 



assume a spindle form ; the longer are often enlarged 

 at one end like a tadpole. The swollen rods may attain 

 a breadth of from 1*8 to 2'6/z. At the same time the 

 plasma becomes more highly refracting, and the mem- 

 brane markedly thickened. When this has taken place 

 spore formation commences ; the ovoid spores are 2 to 

 2*5 p. in length, and 1 /*. in breadth, they become free 

 by solution of the membrane of the mother cell. The 

 spores sprout in the following manner : At one of the 

 pointed ends of the longish spore the double contour of 

 the spore membrane disappears, and the germinating 

 tube passes out ; the longitudinal diameter of the latter 

 is parallel to that of the spore. The dense spore 

 membrane does not shrink, and often remains attached 

 to the young rod for a long time. 



This bacillus is a typical anaerobe; its whole vital 



M 



<a c > 



000^ 



Fig. 98. Bacillus butyricus (after Prazmowski) X 1020. 



A and 5, colonies and chains of bacilli. 



C, colonies with swollen, spindle-shaped, and spore -forming bacilli. 



D, germination of the spores ; a to i t successive stages. 



functions seem to go on quite independently of the 

 presence of free oxygen, and, in fact, they are inter- 



