60 PROTOZOAN PARASITISM 



are undoubtedly primary pathogenic organisms, ca- 

 pable within themselves of invading the wall, al- 

 though the host is commonly able to limit the extent 

 of penetration. Whether they may be purely lumen 

 dwellers is yet unsettled. Previous opinions on this 

 question, even by those who may speak most authori- 

 tatively, are subject to error in the unknown. In 

 considering the possibility it should not be forgotten 

 that the amoeba may be grown apparently indefi- 

 nitely as a "lumen dweller" in a culture tube. It 

 should also be borne in mind that pathological find- 

 ings in the intestine at autopsy in the hands of care- 

 ful and experienced pathologists and in large services 

 are not in proportion to the common relatively high 

 incidence of the infection as reported from stool 

 examination. Is it possible that even minute lesions 

 which must be so commonly present unless this am- 

 oeba is frequently a pure lumen dweller should have 

 been so completely overlooked? 



The writer hesitates to acknowledge that in a con- 

 siderable autopsy experience a condition in which 

 there existed a special interest was not found. And 

 yet such must be the case if Endainoeha histolytica 

 always invades the intestine wall. Naturally the 

 intestine has not been minutely examined always, 

 nor have a great number of microscopic sections been 

 done as a practice, but recently, at any rate, extra 

 care has been exercised and if a common intestinal 

 lesion, even small, has been overlooked it will take 

 virtual serial section to reveal it. In this connection 



