386 A MANUAL OF BACTERIOLOGY 



proportion of lactic acid, together with a small amount of 

 succinic acid, and gaseous carbonic acid and hydrogen. 1 

 Nitrates are reduced to nitrites. 



No toxin, or a trace only, is formed in cultures, but 

 the dead bacilli are toxic and pyogenic, and a toxin is 

 obtained by autolysis of cultures or by triturating the 

 bacilli with liquid air (Macfadyen). 



Vaughan, 2 by washing large quantities of colon and 

 typhoid bacilli, extracting the bacterial cells first with 

 alcohol, then with ether, and then digesting the ground 

 residue with alcohol containing 2 per cent. NaOH, states 

 that two constituents are obtained, one soluble in alcohol 

 and toxic, the other insoluble in alcohol and non-toxic. 

 The latter confers a certain degree of immunity on animals 

 injected with it. 



Pathogenicity. The pathogenic action and pathogenicity 

 of the B. coli are very varied. Introduced into the circu- 

 lation or into the peritoneal cavity in guinea-pigs or rabbits 

 it usually causes death in from one to three days with a 

 general septicaemia. Some varieties are, however, non- 

 virulent to animals. 



In man the colon bacillus is associated with a number 

 of important pathological processes. It is usually the 

 organism causing the peritonitis which is due to infection 

 from the intestine, as in hernia with obstruction or per- 

 foration, in ulceration of the bowel and enteritis, in can- 

 cerous growths, and affections of the appendix, biliary 

 canals, and gall-bladder. The exudation in these cases 

 is often characteristic ; at first it is clear and greenish, 

 it then becomes greenish-yellow, thin, semi-opaque and 

 foul-smelling, and finally purulent. The colon bacillus 

 may pass through the intestinal wall where it has been 

 damaged, but not yet perforated, as in strangulation. 



1 See also Eevis, Cenlr. f. Bakt. (2t Abt.), xxvi, 1910, p. 161. 



2 Trans. XIV Internal. Cong. Hygiene (Berlin, 1907), Bd. iv, p. 28. 



