22 PARASITIC AMCEB^E OF MAN. 



The protrusion of pseudopodia is not always fol- 

 lowed by locomotion for organisms are frequently 

 observed from which pseudopodia are protruded con- 

 stantly and as constantly withdrawn, but there occurs 

 no change in position. The pathogenic amoebas are 

 generally more actively motile than the non-patho- 

 genic species. 



The pseudopodia are always formed by the ecto- 

 plasm and are well defined in some species, while in 

 others no differentiation can be made between the 

 pseudopodium and the endoplasm. This difference 

 in the appearance of the pseudopodia is of some value 

 in distinguishing species. 



Pseudopodia vary greatly in size and shape in 

 different species, in some being spinose and very 

 delicate in appearance ; in others finger-like and dense 

 in structure; while in still others they are broad and 

 blunt. In some amcebse they are so characteristic 

 in appearance as to be of great service in species 

 differentiation. Thus in Entamoeba coli the pseudo- 

 podia are blunt and of a delicate veil-like appear- 

 ance, while in Entamoeba histolytica they are much 

 longer and finger-like in shape and present a dense, 

 glassy appearance. In some of the free-living forms 

 the pseudopodia are always spinose in shape, differ- 

 ing entirely in appearance from those of the parasitic 

 amoebae. I have never observed spinose pseudopodia 

 in any of the parasitic amoebse of man. 



