418 VETERINARY BACTERIOLOGY 



fresh plate. Musgrave and Clegg recommend running the tip of the 

 lens against such an organism and removing it, attached to the 

 lens, and inoculating the new medium by running the lens down 

 in contact with it. 



Entamoeba coli 



Synonym. Amoeba coli. 



Disease Produced. The organism is probably non-pathogenic. 



The Entamceba coli was probably seen and recognized by Lambl 

 in 1860. Since that time it has been repeatedly noted by many 

 investigators. Schaudinn, in 1905, first clearly differentiated 

 the organism and traced its life history. His work has been con- 

 firmed and extended by Craig in the United States. The organ- 

 ism is present in a large percentage (50 per cent., according to 

 Schaudinn) of healthy individuals. It is most easily recognized 

 in the feces after the administration of a saline cathartic. 



F 2 



Fig. 186. Entamceba coli: A, Non-motile form; B, cell showing pseudopodia ; 

 D, E t stages in cell division; F, G, H, 7, /, stages in encystment and sporula- 

 tion (adapted from Craig). 



Morphology. The E. coli is a mass of protoplasm not possess- 

 ing a definite cell-wall, but with a nucleus containing usually one 

 or more nucleoli. One (rarely more) non-contractile vacuole is 

 occasionally present. The organism varies from 8 to 50 // in 

 diameter, but in the majority of cases is between 10 and 20 u. 

 When encysted, it is usually between 10 and 15 u. The organism is 

 approximately spherical when not in motion. It is sluggishly 

 motile, and usually is not moving when observed in a hun^ini; 

 drop. In this it is of a dull gray color. The protoplasm cannot 

 be differentiated into endoplasm and ectoplasm when the organ- 

 ism is at rest. When in motion, the ectoplasm may sometimes be 

 seen. This fact is of considerable diagnostic value. The endo- 



