96 PROTOZOAN PARASITISM 



the progressive motility of the amoeba in a passive 

 way, along with the other inner contents. It is best 

 seen as the amoeba changes its position, when there 

 is protruded a long pseudopod into which flows the 

 endoplasm. As the nucleus moves into the forward 

 pseudopod it may be plainly seen. 



The endoplasm in this phase is usually grossly 

 vacuolated and contains numerous food bodies of a 

 variety, bacteria, yeasts, Blastocystis, crystals, and 

 even the cysts of other protozoa. These objects give 

 evidence of its natural food supplies. In contrast, 

 Endamoeba histolytica seldom contains bacteria and 

 probably never consumes these other objects com- 

 monly seen in E. colL As a rule Endamoeba coli 

 does not eat red blood corpuscles ; in fact it seldom has 

 the opportunity, but it may apparently do so under 

 certain conditions. The writer (1924) incubated at 

 37.5°C. portions of fresh stool containing large num- 

 bers of sluggish amoebae in test tubes containing 

 0.9% sodium chloride solution to which was added a 

 small amount of fresh human blood. Within two 

 hours the amoebae became very active in motility and 

 had ingested many red blood corpuscles. Subse- 

 quent repeated examination of the stools of this per- 

 son never revealed any but an eight nucleated 

 amoeba cyst, identified as E. coli. The only question 

 arising about the identification of the amoeba of this 

 experiment is raised by Kofoid and Swezy's (1921) 

 description of a new genus, Councilviania, the species 

 of the human intestine named Councilviania lafleuri, 



