416 MANUAL OF BACTERIOLOGY. 



hyaline halo, otherwise homogeneous; a single contractile vacuole. Encyst- 

 ment early in cultures; cysts circular or oval; 7.5-14 mikrons; wall single, 

 double contoured regular; contents coarsely granular; nucleus not visible. 

 Sporulation frequent; spores numerous spheroidal, .7-2 mikrons. Movement 

 very active. Habitat, intestinal tract of the guinea-pig. 



Ameba hominls Walker. Ameboid stage circular when at rest, oval, obovate 

 or oblong when in motion, 6.5-15.4 mikrons at rest; pseudopodium single lobose; 

 ectoplasm apparently only in the pseudopodium, hyaline; entoplasm finely 

 granular; nucleus circular, surrounded by a narrow halo 2.8-4.3 mikrons; 

 a single contractile vacuole. Encysted stage assumed late and slowly in cultures; 

 cyst circular, 4.6-7.7 mikrons wall single, double contoured, regular; contents 

 finely granular, nucleus not visible. Sporulation very frequent; spores spher- 

 oidal, numerous, .3-. 8 mikrons. Habitat, intestinal tract of man. 



Ameba musculi Walker. Ameboid stage circular in resting stage; oval, 

 oblong, obovate, or slightly irregular when in motion; 7.7-13.9 mikrons when 

 at rest; pseudopodium, single, lobose; ectoplasm occupying about half the 

 ameba, hyaline; entoplasm containing a few coarse granules; nucleus spheroidal 

 but plastic, surrounded by a broad halo, otherwise homogeneous, 2.3-3.1 

 mikrons; single contractile vacuole. Encysted stage assumed only after 

 a very long time and very slowly in cultures; cysts circular or oval, 6.2-7.7 

 mikrons; wall single, double contoured, regular; contents granular, nucleus not 

 visible. Sporulation rather infrequent; spores not very numerous, spheroidal, 

 1-2.3 mikrons. Movement fairly active, amebas wandering far beyond bacterial 

 growth. Habitat, intestinal tract of house mouse. 



Ameba gallopavonis Walker. Ameboid stage circular when at rest, oval 

 oblong or irregular when in motion, 18.5-30.8 mikrons in resting stage; pseudo- 

 podium normally single, short blunt; ectoplasm more or less distinct, hyaline; 

 entoplasm granular; nucleus circular, 3.4-5.1 mikrons, surrounded by a medium 

 wide halo; a single contractile vacuole; encysted stage assumed rather slowly 

 in cultures; walls two; inner wall very irregular, as if the ameba had become 

 encysted in the ameboid shape; outer wall fairly regular, separated from the 

 inner wall but touching it at the angles, 12.3-20.8 mikrons. Sporulation 

 occasional; spores few, 5-9 spheroidal, 1.2-1.5 mikrons in diameter. Move- 

 ment sluggish. Habitat, intestinal tract of the turkey. 



Ameba ranee Walker. Ameboid stage circular when at rest, oval, oblong 

 or irregular when in motion, 10.8-15.4 mikrons when at rest; pseudopodium 

 single, broad; ectoplasm slightly evident in the resting ameba, hyaline; ento- 

 plasm containing scattered coarse granules; nucleus circular, 1.5-3 mikrons 

 with a relatively broad halo, otherwise homogeneous; a single contractile 

 vacuole. Encysted stage assumed slowly in cultures; cysts circular in outline, 

 9.8-14 mikrons; wall single, double contoured, regular; contents granular; 

 Sporulation moderately frequently; spores 8-16, spheroidal, 1.2-1.5 mikrons. 

 Movement sluggish. Ameba do not wander from bacterial growth in culture. 

 Habitat, intestinal tract of frog. 



Ameba muris Grassi. Ameboid stage circular when at rest, 5.4-8.5 mikrons, 

 oval, oblong, occasionally slightly irregular when in motion; pseudopodium, 

 single lobose; ectoplasm and entoplasm scarcely differentiated; hyaline with 

 fine, scattered granules; nucleus very small, spheroidal, with a narrow halo. 

 Encysted stage late, cysts circular, 3.9-5.4 mikrons; wall single, double, con- 

 toured, regular, concentrically separated from the contents in old cysts; contents 

 finely granular. Sporulation rather late; spores minute, spheroidal. Move- 

 ment sluggish; amebae do not wander from bacterial growth. Habitat, intestinal 

 tract of mouse. 



Ameba intestinalis Walker. Ameboid stage circular when at rest; oval, 

 oblong, or less often irregular when in motion; size 9-26 mikrons when at rest; 



