232 PATHOGENIC MICROORGANISMS. 



AMCEBIC COLITIS. 

 Amoeba Coli. 



History. In certain forms of chronic dysentery accom- 

 panied with ulcerations of the lower bowel, and which very 

 often give rise to suppuration in internal organs, especially 

 the liver, an animal parasite, the Amoeba coli, has been accu- 

 rately described since 1875 by Losch, of St. Petersburg. 

 Losch's observations have been confirmed since by a number 

 of other observers. 



According to Schaudinn, the amoebae coli of Losch are really 

 two distinct organisms, one of which is sometimes found in 

 the intestines of healthy people, giving rise to no symptoms, 

 and the other giving rise to the amoebic dysentery as found in 

 the tropics. 



He calls the harmless amoeba Entamoeba coli, and the dys- 

 entery amoeba the Entamoeba Jiistolytica, and gives the method 

 of differentiating between the two as follows : In the dysenteric 

 form the external membrane, or ectoplasm, is more plainly de- 

 veloped and refractile and hyaline than the Entamoeba coli. 

 In the Entamoeba coli the hyaline pseudopodial plasma, in 

 contrast to the remaining plasma, is much less refractile than 

 the Entamoeba histolytica, in which there is always a plainly 

 developed ectoplasm existing as a plasma zone, and possessing 

 a stronger refraction than the endoplasm. The nucleus of 

 Entamoeba histolytica is very difficult to see in fresh speci- 

 mens. Its position is excentric, its shape is changeable. 



Morphology. The amoeba is a protozoon, and consists of 

 protoplasm which exhibits under different conditions various 

 forms. In the quiescent condition it is spherical in shape, 

 and may be recognized from the other cellular elements by 

 its greater refraction of light and by its pale-green color. Its 

 size is from 10 to 25 mikrons. The body consists of two 

 parts : an inner part, or endoplasm, which is generally gran- 

 ular and of dark color ; and an outer part, or ectoplasm, which 

 is pale and white. These two parts may be best made out in 



