DYSENTERY. 369 



tion is one of mixed infection. This is, however, not prob- 

 able, as all of the bacteria found were not virulent for the 

 animal on infection by enema, although the pus from a 

 liver-abscess that contains only amebae and no bacteria 

 will induce dysentery in cats. It is more probable that 

 secondary infection with these bacteria, all of which are 

 regular inhabitants of the intestine, has taken place. What 

 modification of the clinical picture of the disease and what 

 portions in the anatomic alterations are to be attributed to 

 the secondary bacterial infection, and how much is due to 

 the amebic infection alone can not for the present be de- 

 cided. 



Portals of Infection for and Transmission of the 

 Amebse. Dysentery is, according to clinical experience, 

 only transmissible in a limited degree from one person to 

 another, and from one place to another. It has not yet 

 been determined through what medium the amebae gain 

 entrance into the body. The results of the experiments of 

 Quincke, already alluded to, render introduction by the 

 mouth possible. Accordingly, infection from case to case 

 could take place directly through the intermediation of the 

 stools. In general, however, direct contagion is not con- 

 sidered probable by clinicians. It is rather assumed that, 

 as a rule, the amebae are taken up from surrounding 

 nature. Drinking-water is believed often to play the role 

 of the intermediary. As has been pointed out, the amebae 

 do not persist in their original form in the stools, but they 

 quickly undergo degeneration. Whether they persist in 

 some as yet unknown vegetative intermediate stage in 

 nature or in another host, or whether after leaving the body 

 they develop permanent forms, has not yet been cleared up. 

 Kruse and Pasquale froze stools containing amebae for a 

 quarter of an hour in a cold mixture. After thawing, no 

 amebae could be detected, not even encysted forms. The 

 stools, however, proved pathogenic for cats, hemorrhagic 

 enteritis, with abundant proliferation of amebae, taking place 

 after introduction into the bowel. With the disappearance 

 of the ordinary forms of amebae observed the parasites evi- 

 dently do not wholly perish. 



It is an open question how the amebae, when introduced 



into the intestine, penetrate the mucous membrane and gain 



access to the submucosa, and whether a lesion of the 



mucosa is necessary for this to take place, or whether, per- 



24 



