462 A MANUAL OF BACTERIOLOGY 



obtained by autolysis of cultures or by triturating the 

 bacilli with liquid air (Macfadyen). 



Vaughan, 1 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 pathogeni- 

 city of the B. coli are very varied. Introduced into the 

 circulation 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-smeUing, and finally purulent. The colon bacillus 

 may pass through the intestinal wall where it has been 

 damaged, but not yet perforated, as in strangulation. 



The B. coli is a pyogenic organism, and has been met 

 with in ischio-rectal abscesses. Possibly it causes in some 

 instances the pneumonia and pleurisy occurring after 

 peritonitis, for it has been obtained from the lung and 

 pleura in these conditions, but it must be recognised that 

 the B. coli is a common secondary or terminal infection. 



1 Trans. XI V Internal. Cong. Hygiene (Berlin, 1907), Bd. iv, p. 28. 



