130 PARASITIC AMCEB^E OF MAN. 



into them, giving them a granular appearance, and 

 in rare instances amcebse of this species are observed 

 in which the motion is so rapid that the distinction 

 between ectoplasm and endoplasm cannot be made. 

 In Entamoeba coli it is often very difficult to dis- 

 tinguish these two portions of the cytoplasm even 

 when the organism is in motion. 



In Entamoeba histolytica the flowing of the endo- 

 plasm into the pseudopodia generally occurs very 

 rapidly and it often appears as though the periphery 

 of the endoplasm ruptured, allowing the contents to 

 rush through into the pseudopodia. Not infrequently 

 a constriction is present in the pseudopodia near the 

 boundary of the endoplasm, and when this is the case, 

 the contents may be seen to pass slowly through the 

 constriction, the nucleus, vacuoles and red corpuscles 

 being compressed as they pass through the narrow 

 portion. 



When motility is pronounced the amoebse gener- 

 ally progress in a definite direction or across a micro- 

 scopic field without cessation of progressive motion; 

 in other instances motion will occur for a short dis- 

 tance in one direction, followed quickly by progres- 

 sion in another, so that it may be a long time before 

 the amoeba will pass out of the field of a one-sixth-inch 

 objective. 



The second form of motility is frequently ob- 



