442 PROTOZOOLOGY 



P. carolinensis Wilson (Figs. 66; 71; 186, b, c). Monopodal forms 

 1-5 mm. long; polypodal forms 1-2 mm. in diameter; locomotion ac- 

 tive; nuclei up to 1000 or more, circular in front view, about 20/x in 

 diameter and ellipsoid in profile; fluid and food vacuoles, crystals, 

 many contractile vacuoles; feeds on various Protozoa and inverte- 

 brates; easily cultivated in laboratory; plasmotomy into two to six 

 individuals; nuclear division simultaneous and synchronous; ex- 

 perimental plasmogamy; no encystment in the Illinois stock, but 

 New Jersey stock is said to encyst (Musacchia, 1950); North Amer- 

 ica. Distribution (Kudo, 1946); morphology (Wilson, 1900; Andre- 

 sen, 1942; Kudo, 1946); plasmotomy (Schaeffer, 1938; Kudo, 1949); 

 nuclear division (Kudo, 1947); locomotion (Wilber, 1946); permea- 

 bility (Belda, 1942-1943); effect of x-irradiation (Daniels, 1951, 

 1952, 1952a). 



P. illinoisensis Kudo (Fig. 186, d, e). The organism resembles the 

 last-named species, but much smaller in size; 500-1000 // in length; 

 clavate forms seldom exceed 1.5 mm.; several hundred nuclei, spheri- 

 cal, 14-16/z in diameter; peripheral granules of the nuclei are large 

 and often discoid, irregularly distributed; crystals occur abundantly 

 in all physiological conditions; chalky white in reflected light; plas- 

 motomy into two to five daughters; encystment and excystment take 

 place freely in cultures; cysts measure 250-350^ in diameter with 

 usually two membranes, a multinucleate amoeba emerges from a 

 cyst after several weeks (Kudo, 1950, 1951). Other species of Pelo- 

 myxa (Kudo, 1951). 



Genus Vahlkampfia Chatton and Lalung-Bonnaire. Small amoe- 

 bae; vesicular nucleus with a large endosome and peripheral chro- 

 matin; with polar caps during nuclear division; snail-like movement, 

 with one broad pseudo podium; cysts with a perforated wall; fresh 

 water or parasitic. Nuclear division (Jollos, 1917). 



V. Umax (Dujardin). 30-40/x long; fresh water. 



V. patuxent Hogue (Fig. 186, /). In the alimentary canal of the 

 oyster; about 20^ long during the first few days of artificial culti- 

 vation, but later reaching as long as 140/* in diameter; ordinarily 

 one large broad fan-shaped pseudopodium composed of the ecto- 

 plasm; in culture, pseudopodium-formation eruptive; holozoic on 

 bacteria; multiplication by fission or budding; encystment rare; 

 cysts uninucleate. 



Genus Hartmannella Alexeieff. Small amoebae, with moderately 

 or well-developed ectoplasm; vesicular nucleus with a large endo- 

 some; mitotic figure ellipsoidal or cylindrical, without polar caps. 

 Cysts rounded; wall smooth or slightly wrinkled in one species. 



