16 PROTOZOA 



P. ruber F. E. Schulze. Color reddish : in fresh water. 



4. AMCEBA Ehrenberg. Body may assume a variety of forms, being 

 often more or less spherical while at rest ; pseudopodia either slender or 

 lobose; nucleus and contractile vacuole present: about 12 species; in 

 fresh and salt water. 



A. Umax Dujardin (Fig. 1). Body small, elongate, without 

 definite pseudopodia and moves by slowly flowing along: in fresh 

 water. 



A. proteus (Pallas) (Fig. 2). Diameter up to .5 mm.; pseudopodia 

 long and usually blunt ; movements often active : in fresh water. 



A. radiosa Ehr. Pseudopodia slender and radiating; body more or 

 less star-shaped; diameter about .04 mm.: on water plants. 



Fig. 3 Fig. 4 Fig. 5 



Fig. 3 Amoeba verrucosa (Conn). Fig. 4 Entam&ba coli (Doflein). 

 Fig. 5 Entamceba dysenteriae (Doflein). 



A. verrucosa Ehr. (Fig. 3). Diameter up to .2 mm.; pseudopodia 

 short; surface folded; movements sluggish. 



5. ENTAIKEBA Casagrandi and Barbagallo. Similar to Amoeba, but 

 parasitic in mammals; size minute; pseudopodia short and sluggish: 

 several species. 



E. coli (Loesch) (Fig. 4). Form roundish or elongate with a dis- 

 tinct nucleus and an indistinct ectosarc; pseudopodia short and slug- 

 gish; diameter .06 mm.: in human colon; formerly supposed to be a 

 cause of dysentery. 



E. dysenteriae (Councilman and Lafleur) (E. Jiistolytica Schaudinn) 

 (Fig. 5). Similar to E. coli but with a distinct ectosarc: in the human 

 colon; the cause of dysentery. 



6. DACTYLOSPHJERITTM Hertwig and Lesser. Small round forms 

 with often numerous long.ray-like pseudopodia, which sometimes vibrate 

 slightly; short and blunt pseudopodia also present when the animal 

 moves: in fresh water. 



D. radiosum (Ehrenberg). Three or 4 long spine-like pseudopodia; 

 diameter .02 mm. 



D. polypodia F. E. Schulze. Numerous finger-like pseudopodia 

 present. 



