354 THE COL/ CLOACA PROTEUS GROUP 



milled light the growths are yellowish-brown ; by reflected light they 

 are colorless. Colonies on gelatin develop more slowly and become 

 somewhat brownish in color. The medium is not liquefied. Rapid 

 development occurs in plain and sugar broths. A heavy, brownish 

 spreading growth occurs on the surface of slanted potato. 



Bacillus coli is an aerobic, facultatively anaerobic organism which 

 grows best at 37 C. Growth ceases below 8 to 10 C., and above 

 43 to 45 C. An exposure of fifteen minutes at 75 C. kills them. In 

 general the colon bacillus is somewhat more resistant to physical and 

 chemical agents than the typhoid bacillus. 



Products of Growth. (a) Chemical. Bacillus coli produces indol 

 from tryptophan in sugar-free media, and phenolic bodies from 



FIG. 48. Bacillus coli flagella. X 1500. (Kolle and Hetsch.) 



tyrosine under the same conditions. Hydrogen sulphide and ammonia, 

 the latter resulting largely from deaminization of proteins and 

 protein derivatives, are also produced in considerable amounts in 

 media containing no utilizable carbohydrates. 1 Similar products 

 may be formed in the intestinal tract under certain conditions. The 

 addition of utilizable carbohydrates to protein media changes the 

 character of the products of metabolism in a noteworthy manner. 

 Under these conditions the protein constituents of the media are 

 practically unchanged; the sugars are fermented with the production 

 of carbon dioxide and hydrogen, 2 lactic acid and smaller amounts of 



1 Kendall, Day and Walker, Jour. Am. Chem. Soc., 1913, xxxv, 1228. 



2 In the proportion H:CO 2 = f . Theobald Smith, The Fermentation Tube. The 

 Wilder Quarter Century Book, 1893, p. 202. Very exact determinations of the gaseous 

 products of fermentation of B. coli have been made by Harden and Walpole, Proc. Roy. 

 Soc., 1906, 77, 399, 



