74 PARASITIC AMCEB^E OF MAN. 



harmless and only of accidental occurrence in patients 

 suffering from dysentery. However, as evidence of 

 the pathogenic action of amoeba? accumulated it was 

 found that such an opinion was untenable. In order 

 to explain the pathogenic action of these organisms 

 the theory regarding the effect of environment arose, 

 together with the belief that more than one species 

 of amoebae occurred in the human intestine. 



OCCURRENCE IN HEALTHY INDIVIDUALS. It is 

 surprising how little work has been done regarding 

 the occurrence of amoebae in the healthy human in- 

 testine. Although several years have elapsed since 

 Schaudinn's paper was published, only a very few ob- 

 servers have undertaken the determination of how 

 large a percentage of healthy individuals show amoebae 

 in the feces, and even those who have combated 

 Schaudinn's classification have not taken the trouble 

 to examine a large number of individuals in health, 

 in order to prove or disprove his results. 



Historical Summary. Grassi, in 1888, was prob- 

 ably the first investigator to demonstrate the presence 

 of amoebae in the feces of healthy individuals, although 

 Cunningham in 1881 stated that he found amoebae in 

 the stools in both healthy and diseased individuals, 

 but his description indicates that he mistook stages 

 in the life cycle of the flagellates for amoebae. Shu- 

 berg demonstrated amoebae in the feces of 10 out of 



