ENDAMCEBA CITELLI SP. NOV. FROM THE STRIPED 



GROUND SQUIRREL CITELLUS TRIDECEM- 



LINEATUS, AND THE LIFE-HISTORY 



OF ITS PARASITE, SPH&RITA 



ENDAMCEBA SP. NOV. 



ELERY* RONALD BECKER, 

 IOWA STATE COLLEGE. 



ENDAMCEBA CITELLI sp. nov. 



In the autumn of 1925 the writer made microscopic exami- 

 nations of the faecal mass from the intestines of eight ground 

 squirrels belonging to the species Citelhis tridecemlineatus. These 

 animals were captured alive at various times in the vicinity of 

 Ames, Iowa, brought to the laboratory, and examined at once 

 for parasitic protozoa. In addition to a number of other inter- 

 esting protozoa, six of the ground squirrels were found to harbor 

 amcebse in their cceca. In four of the animals the amoebae' were 

 extremely rare, but two showed extremely heavy infections. 

 The movements of the live amoebae were studied in normal saline 

 solution, and permanent mounts were made by the well-known 

 Schaudinn-iron-hacmatoxylin method. 



The amoebae live within their host in association with myriads 

 of other protozoa. The habitat is limited to the ccecum and 

 the part of the colon immediately adjoining. Localization in the 

 ccecum has been noted by Kessel (1924) in the case of several 

 species of rat and mouse amoebae. Kessel thinks the PH relation- 

 ship has something to do with this localization of habitat. 

 Perhaps another factor is the more fluid content of the ccecum 

 which makes a more favorable medium for amoebae than the 

 colon, where the water content is very much reduced by ab- 

 sorption. 



Examination of the substances in the food vacuoles of the 

 amoebae show that they feed largely upon bacteria and nondescript 

 particles of undigested vegetable matter. The food vacuoles and 

 cytoplasm often contain a curious parasite of the amoeba which 



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