330 MANUAL OF BACTERIOLOGY. 



tensive ulceration.* According to Strong,f at least two distinct 

 species of amebae have been found in the feces in man, only one 

 of which is pathogenic and the cause of dysentery. Unfortu- 

 nately the designation, Amaeha coli, has been applied to both 

 species. The ameba of dysentery should be designated Anueba 

 dysentericz, limiting the term Amceba coli to the non-pathogenic 

 form or forms. 



The Amceba dysenterice is a unicellular organism, 20-50 /^ 

 in diameter when at rest, consisting of a clear, homogeneous 

 ectosarc and a granular endosarc, with an eccentrically placed 

 nucleus. The endosarc contains a number of vacuoles of 

 variable size and very frequently red blood-corpuscles, as well 

 as other foreign bodies, such as bacteria, pigment granules, 

 etc. Many red blood-corpuscles may be seen crowded together 

 in a single ameba. The organism is actively ameboid, extending 

 its substance into processes or pseudopodia of varying forms. 

 This ameboid motion assists in making easy the recognition 

 of the parasites under the microscope and in distinguishing 

 them from large, swollen cells found in the feces. The stool 

 should be examined while fresh and still warm. 



The non-pathogenic ameba (Amceba coli), also occasionally 

 found in the intestinal tract of man, differs from the pathogenic 

 dysenteric organism chiefly in its much smaller size (10-24 ,"■) 

 and the invariable absence of red corpuscles from its interior. 

 The protoplasmic granules are also, as a rule, smaller and are 

 difficult to recognize. The Amoeba dysenterias produces ex- 

 perimentally definite ulceration of the gut of cats, whereas the 

 Amoeba coli is harmless. Both varieties of amebag may be 

 stained by a special stain devised by Mallory.J 



* Councilman and Lafleur. Johns Hopkins Hospital Reports. Vol. II. 

 Harris. American Journal Medical Sciences. Vol. CXV. 1898. 



t Strong. Circulars on Tropical Diseases. No. i. Chief Surgeon's OflSce, 

 Headquarters, Division of the Philippines, Manila, P. I. Febi-uary, 1901. 

 Ibid. No. II. April, 1901. (Both reports may be obtained from the United 

 States Government, Washingtoft.) 



X Mallory. Journal of Experimental Medicine. Vol. II. P. 529. Sep- 

 tember, 1897. 



