370 CLINICAL BACTERIOLOGY. 



haps, with the cooperation of the bacteria, they are capable 

 of passing through the intact mucous membrane. Accord- 

 ing to clinical observation, exposure to cold and disorders 

 of digestion favor the development of dysentery. It thus 

 appears that an especial local predisposition for amebic in- 

 fection is necessary in precisely the same way as for bac- 

 terial infection. 



Abscess of the Liver. Abscess of the liver, which 

 occurs so frequently in tropical regions, has long been 

 associated clinically with dysentery. It has mostly been 

 considered as a sequel of the latter disease. As a matter 

 of fact, the pus and the abscess-membrane in cases of 

 tropical abscess of the liver almost invariably contain the 

 same amebae that cause dysentery. When the amebae are 

 absent from the pus, there is generally no relation to dysen- 

 tery ; so that the presence of amebae may be utilized as a 

 point in the differential diagnosis between idiopathic and 

 dysenteric abscess of the liver. Naturally, careful and 

 repeated examination of the contents of the abscess is 

 necessary, as not every specimen of the pus will contain 

 the amebae, which are present in the abscess in varying 

 number. 



Bacteriologic examination of the pus from hepatic ab- 

 scesses containing amebae has yielded a positive result in 

 the majority of cases,, streptococci, staphylococci, colon- 

 bacilli, and other bacteria being found present also. Only 

 a small proportion of the abscesses are sterile. If the pus 

 free from bacteria contains living amebae, practically a pure 

 culture is present, which may then be employed experi- 

 mentally. 



It is an open question, further, what role in the devel- 

 opment of abscesses of the liver is played by the bacteria, 

 as all of them possess pyogenic activity. It is possible 

 that the amebae injure the liver-tissue, and that the bacteria 

 then secondarily induce suppuration. It is a question, also, 

 as to how the amebae gain entrance into the liver. In this 

 connection the portal circulation, the peritoneum, the lym- 

 phatic vessels, and the biliary passages, must be considered 

 as possible media of infection. Dissemination of the 

 amebae through the blood-stream appears the more prob- 

 able, as they have been found repeatedly in the intestinal 

 wall, within the lumen of vessels. Penetration of the in- 

 testinal wall and infection from the peritoneum also appear 



