OCCURRENCE OF CAUSATIVE AGENTS. 155 



Experiments on Animals. If, after ligation of the 

 choledoch duct, coli-bacilli are introduced in the central 

 portion of the duct, the animals (dogs, rabbits) die as a 

 result of purulent cholecystitis and cholangitis. If the 

 bacilli are injected directly into the mouth of the choledoch 

 duct after the duodenum has been opened, the same result 

 is obtained if the coli-cultures are sufficiently virulent. 



The bacteriologic diagnosis can be made only in cases 

 of empyema of the gall-bladder, aseptic puncture being 

 practised and plates being cast with the bile obtained. Such 

 puncture, however, should not be undertaken unless urgently 

 indicated, as even when made with most careful aseptic 

 precautions, signs of peritoneal irritation, usually mild, 

 follow. 



ABSCESS OF THE LIVER. 



So-called biliary abscesses belong in the domain of cho- 

 langitis. Pyemic abscesses of the liver constitute part of a 

 purulent general infection. (See Pyemia and Its Causes, p. 

 1 6 1.) Hepatic abscesses in the sequence of gastro-intes- 

 tinal lesions arise through the intermediation of the portal 

 vein ; coli-bacilli act as exciting agents. With regard to 

 tropical abscesses of the liver, the section on Dysentery may 

 be consulted. 



In the bacteriologic diagnosis the pus obtained on ex- 

 ploratory puncture with a sterile hypodermic syringe in 

 the search for the abscess is subjected to examination. 



CYSTITIS. 



Numerous investigations in recent years have shown that 

 the bacterium coli commune, or the bacterium aerogenes, 

 plays the most important part in the etiology of cystitis. 

 The other microbes of suppuration and inflammation also 

 deserve consideration in this connection, but they occur- 

 less frequently than the aerogenes and the coli. An excep- 

 tion is formed by puerperal cystitis, following parturition, 

 with which the streptococcus pyogenes and the staphylo- 

 coccus pyogenes are equally associated ; also by gonorrheal 

 cystitis, which, in part at least, is dependent upon the gono- 

 coccus, and by tuberculous cystitis, which is caused by the 

 tubercle-bacillus. 



