194 PATHOGENIC MICROORGANISMS. 



AMOEBIC 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. 



Morphology. The amoeba is a protozoa, 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 

 the motile amoeba. A nucleus more or less central is also 

 easily made out. 



The Amoeba coli is stained easily by any of the nucleolar 

 stains, especially by methylene-blue. In its body may often 

 be seen foreign bodies, especially red blood-cells, but it rarely 

 contains leucocytes or fat. 



The motion of the amoeba is caused by the mechanism of 

 pseudopodia, which are blunt homogeneous processes, the pro- 

 trusion of a portion of the ectoplasm. Motion is sometimes 

 gradual and deliberate, at other times rapid, and is modified 

 by variations in temperature. 



Biology. Nothing is known as to the functions of nutri- 

 tion, respiration, and reproduction of the amoeba. It is found 

 occasionally in health in the secretions of the lower bowel, 

 and in cases of dysentery may disappear partially or com- 

 pletely from the stools during convalescence. They are also 

 frequently found in the pus of hepatic abscesses. 



Examination of the feces, especially the slimy portion of 



