PROTOZOA IN THE DIGESTIVE TRACT 21 



ous. The various food particles seen in life are stained black 

 to gray, in some of which reticulation is visible. Many 

 bacteria occur also as food particles. The spherical nu- 

 cleus is vesicular and measures about 2-4|j in diameter. 

 There is a small endosome near the center, while the 

 peripheral chromatin granules are small and compactly 

 packed along the inner surface of the membrane so that 

 the latter frequently appears as a uniformly thick ring. 

 Depending on the degree of decolorization, there may 

 be seen a clear zone around the endosome and the rest 

 occupied bv an achromatic network. The stained speci- 

 mens are a little smaller than the living ones. 



Although this amoeba is the very first parasitic amoeba 

 seen by man and has been studied by numerous work- 

 ers, encysted forms have, as stated already, not yet been 

 observed. Therefore, the transmission appears to be carried 

 on by the trophozoite. Koch (1927) found the effects of 

 desiccation and varied temperatures upon the amoeba, as 

 follows: The amoeba is killed at C. in 18 hours; 5^C. in 

 24 hours; 10°C. in 48 hours; 45°C. in 20 minutes; 50°C. 

 in 15 minutes; 55 °C. in 2 minutes. At 40° C. survival is 

 possible for an indefinite length of time. Complete desic- 

 cation of the medium or immersion in water at 60° C. 

 kills the amoeba. She considered that E. gingivalis may be 

 disseminated both by direct contact and by an interme- 

 diate contaminated article. 



4. lodamoeha hiitschlii (Prowazek 1912) 



Synonym: /. williamsi (Prowazek 1912) 



This amoeba is intermediate in size between the two 

 intestinal amoebae already described and the two smaller 



