ENTAMCEBA COLI 545 



amebae multiply as freely as on Petri dishes. The film of agar medium 

 is thin enough to permit the use of a 2 mm. oil-immersion lens. 



Pathogenic Amebae. Amebae have frequently been found in the 

 intestinal tract of man and the lower animals. They were perhaps 

 first seen in 1859 by Lamble and demonstrated beyond a doubt 

 by Loesch in 1875, who found them in the discharges of a patient 

 suffering from chronic dysentery. Loesch called the organism 

 Amoeba coli, and claimed that he was able to produce dysentery in 

 dogs by the injection of the feces containing them. Amebse as the 

 possible cause of disease in man or animals, however, did not attract 

 much attention until Robert Koch, while studying Asiatic cholera 

 in Egypt, found them in the tissues of the intestines of three persons 

 who had died from chronic dysentery. Koch's observations stimu- 

 lated the work of Kartulis, who found amebse in the stools of 150 

 sufferers from dysentery, and who published his investigations in 

 1886. Observations in this country were then made by Osier, 

 Musser, Stengel, Dock, Councilman and Lafleur, Harris and others. 

 While, for a number of years, there has been no doubt that amebse 

 are found in certain dysenteries in man, their role in the production 

 of this disease has been again and again in doubt, as it has been 

 shown that they occur in all forms of diarrhea and frequently in 

 the stools of perfectly healthy persons and in the intestines of many 

 species of animals which are in a normal condition of health. Walker 

 recently described 37 species of amebse (including several previously 

 undescribed species) in the intestines of man, the horse, pig, dog, 

 cat, rabbit, guinea-pig, rat, house mouse, white mouse, etc., the 

 great majority of which, beyond doubt, are perfectly harmless com- 

 mensales in the intestines of their host. The question of the patho- 

 genicity of amebse in man has been much clouded because most 

 observers had not learned to differentiate a harmless commensale 

 from a truly pathogenic organism. Two observers in particular, 

 Schaudinn and Craig, however, have clearly shown that one common 

 non-pathogenic ameba and one pathogenic species are really found 

 in the intestines of man. Schaudinn was the first to describe these 

 two types definitely. Craig made some early observations independent 

 of Schaudinn, and later confirmed all of Schaudinn's observations as 

 to the fundamental difference between the two types. Schaudinn 

 named the harmless commensale in the intestines or man Entamceba 

 coli, and the pathogenic organism which is the cause of so-called 

 amebic dysentery Entamosba hystolytica (histolytica, tissue dissolving). 



Entamoeba Coli. This harmless commensale was found by Schaudinn 

 in the feces obtained after purging in 50 per cent, of healthy persons 

 examined in West Prussia; in 20 per cent, of persons examined in 

 Berlin, and in 66 per cent, of persons examined along the shores of 

 the Adriatic. Craig found this organism in 65 per cent, of healthy 

 American soldiers examined in San Francisco; Ashburn and Craig, 

 in 71 per cent, of healthy American soldiers in Manila, and Vedder, 

 35 



