1064 PATHOGENIC PROTOZOA 



threw doubt upon the existence of a form of dysentery due to amoeba, 

 since it was found not infrequently in healthy individuals. Schau- 

 dinn found it present in the stools of 50 per cent of the persons 

 examined in East Prussia, in Berlin in 20 per cent, and in Istria 

 in 60 per cent. Craig, and Craig and Ashburn found it present in 

 176, or 58 per cent, of 307 examinations of healthy American soldiers. 

 Craig was able to follow some individuals for four to six years, 

 during which time they constantly showed Entamoeba coli in the 

 feces, yet never developed dysentery. The organism seems to be 



FIG. 127. ENTAMCEBA COLI. Small precystic form. (Army Med. School Collec- 

 tion, Washington, D. C.) 



found iii all countries, regardless of climate. Its recognition and 

 separation from histolytica we owe to Schaudinn, Jurgcns, Craig 

 and others. 



In size it varies from ten to forty microns, the average being 

 between twenty and thirty. The ecto'plasm is never seen except 

 during movement, and it is then hyaline, and only slightly refractile, 

 and much more fluid than in histolytica. The digestive vacuoles 

 rarely, if ever, contain red blood cells, but are filled with cocci and 

 bacilli, a form of food not seen in healthy histolytica. In general, 

 the vacuoles are larger and more numerous in coli than in histolytica, 

 and the motility is feebler. In fresh specimens the nucleus is rather 



