28 Synopsis of the Bacteria and Yeast Fungi. 



In various infusions and substances ; most probably also 

 in the rennet-stomach of living animals. 



Fig. 19. — Bacillus subtilis, 5< 4000 (after Dallinger). 



According to Cohn, it produces the butyric fermentation and is also 

 the efficient cause in the ripening of cheese. 



An extraordinary and peculiar power of resistance is possessed by 

 the spores of B. subtilis and other species. They are not killed off 

 by boiling, but are thereby excited to speedier germination, which of 

 course brings into consideration the duration of the boiling. A quarter 

 of an hour's boiling does them absolutely no harm, while after an hour 

 most of them, and after two hours all of them are killed. Heating 

 them above 80° C. kills them sooner. They are not affected by poisons 

 and weak acids. 



40. B. tremulus, Koch, in Cohn {I.e., ii. p. 417). 



- f\ Very similar to 



jy ^^'''®^^=«B=3!a=: a ^^ preceding, but 



more slender and 

 usually also shorter, 

 always with a flagel- 

 lum at each end. 



'«©» \ 



Spores conspicuously 



Fig. 20.— a, Bacillus suitilis; b, B. tremulus, with thicker than the CcUs, 

 spores ; c, ^. fl«^Anzc/j, united in threads, form- often lateral /Fie" 



ing spores, X 500 (all after photographs by Koch). * ^ °' 



20b). 



On the surface of decaying plant infusions, forming a 

 thick gelatinous membrane. 



