76 PROTOZOAN PARASITISM 



tion, with only minor tissue penetration by the 

 amoeba, but produced by their cytolytic substance. 

 Here there is superficial necrosis and sloughing, the 

 shallowness of the ulcer obscuring it from the casual 

 examiner. 



Interestingly, Councilman and Lafleur (1891) de- 

 scribe a superficial mucosal necrosis and softening of 

 epithelium, along with the typical undermined ulcer 

 in amoebic dysentery, which they believed to be 

 produced by the cytolytic activity of amoebae on 

 the surface. 



While such a state of the surface epithelium in the 

 acute form, amoebic dysentery, is consistent with 

 the state of the intestine, it is difficult to relate it 

 with a chronic condition. Further investigation will 

 be required to show that such surface lesions are 

 of amoebic origin and that they are a characteristic 

 state of the chronic phase of the disease. 



It is somewhat difficult at the present to evaluate 

 the various findings and beliefs. It is, perhaps, sig- 

 nificant that some of the most experienced workers 

 who once believed that Endamoeba histolytica is an 

 obligatory tissue invader, that its presence in the 

 intestine always signified tissue destruction, have 

 changed their minds and are now convinced that the 

 organism may dwell only in the lumen at times. 



All of which comes to the possibility that the 

 symptomless "carrier" state of intestinal amoebiasis, 

 possibly the condition of chronic intestinal amoebia- 

 sis, covers the large group of infections by Endamoeba 



