PATHOGENIC PROTOZOA. 417 



pseudopodium single, short, broad; ectoplasm scarcely apparent except in 

 pseudopodia, hyaline, entoplasm coarsely granular, frequently vacuolated; 

 nucleus circular, but somewhat plastic, surrounded by a broad halo, otherwise 

 homogeneous, 3,1-6.2 mikrons in diameter; a single contractile vacuole. En- 

 cysted stage assumed early, and rapidly; cysts irregular from the beginning 

 walls two; inner wall irregularly polygonal, scalloped or ovoid; outer wall 

 wrinkled and touching in the inner wall at its angles; contents of cysts coarsely 

 granular, nucleus frequentiy visible. Sporulation moderately frequent; spores 

 numerous, spheroidal, .5-1.5 mikrons. Movement not very active, but the 

 ameb£e wander widely over the culture medium. Habitat, intestinal tract of the 

 horse, pig, cat, turkey and perhaps other animals. 



_ Ameba enterica Walker. Ameboid stage circular when at rest, oblong or 

 irregular when in motion; 9.2-15.4 mikrons in diameter when at rest; pseudo- 

 podium normally single, blunt, narrow; ectoplasm apparent only in the 

 pseudopodia, hyaline; entoplasm finely granular; nucleus circular in outhne, 

 3.1-6.2 mikrons, surrounded by a broad halo, otherwise homogeneous; a single 

 contractile vacuole. Encysted stage assumed late and slowly; cysts at first 

 circular, later slightly irregular; walls two; inner wall circular, double contoured, 

 at first circular, later becoming polygonal, or lobed in outline; contents finely 

 granular, nucleus not visible; sporulation rather frequent; spores numerous, 

 spheroidal, .8-2 mikrons. Motility moderately active. Habitat, intestinal tract 

 of the rabbit, cat, rat, mouse, turkey, and perhaps other animals. 



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

 or irregular when in motion, 6.2-15.4 mikrons; pseudopodium normally single, 

 lobose; ectoplasm and entoplasm not differentiated, finely granular, frequently 

 vacuolated, feebly refractive; nucleus small spheroidal, surrounded by a narrow 

 halo, a single contractile vacuole. Encysted stage assumed rather early in 

 cultures; cysts circular or slightly irregular, 3.1-7.8 mikrons; wall single, im- 

 pervious to stain; contents regularly contract from one or two segments of the 

 wall. Sporulation rather infrequent; spores minute. Movement slow. Habi- 

 tat, intestinal tract of various vertebrate animals, and probably also free. 



Other amebae have been described in connection with various diseases of 

 animals, but owing to lack of exhaustive descriptions these could not be brought 

 under the classifications of Walker given above, though doubtless some of them 

 in reality belong to one or the other of the species given above. Ameba dysen- 

 tertcB of Councilman and 'L?Ae\xr dysenterica, Kartulis, coli felis Quinke and Roos, 

 coli mitis ebenda, inkstini vulgaris ebenda, lobosa coli Celli e Fiocca, entameba 

 hominis Casagrandi e Babagallo, coli Schaudinn are all regarded as identical 

 with Ameba coli Loesch. Unidentified or identified with reserve are ameba 

 bovis Liebetanz, bucallis Sternberg, bentali Grassi, gingivalis Gross, kaHulisi 

 Doflein, miurai Ijima, pulmonalis Arlault, ranarum Grassi, urogenilalis Baelz, 

 buccalis Prowazek, undulans Csatellanil, gemmipara Schaudinn. 



The Malarial Parasite* (Plasmodium or Hsmatozoon 

 Malariae). — The organisms of malaria consist of at least three 

 different species, each associated with one of the three types 

 of malarial fever: The tertian parasite with benign tertian 

 malarial fever, the parasite reaching maturity in forty-eight 



*See Thayer and Hewetson. The Malarial Fevers of Baltimore. Johns 

 Hopkins Hospital Reports. Vol. V. 1895. Thayer. Lectures on the 

 Malarial Fevers. New York. 1897. 

 27 



