644 PROTOZOOLOGY 



giants are carnivorous individuals feeding on small bacteria-fed in- 

 dividuals or other ciliates and remain large (with larger macronucle- 

 us and undulating membrane) after division, as long as appropriate 

 diet is supplied. 



Genus Protocruzia Faria, da Cunha and Pinto. Peristome does 

 not turn right, leads directly into cytostome; convex left side not 

 ciliated, but bears bristles; flat right side with 3-5 faintly marked 

 ciliary rows; peristome begins at pointed anterior end and extends 

 1/4-1/3 the body length; cytopharynx (?); macronucleus simple; 

 contractile vacuole subterminal ; salt water. 



P. pigerrima (Cohn) (Fig. 302, j). About 20/x (da Cunha); 50- 

 60^1 long (Kahl) ; peristome 1/4-1/3 the body length; salt water. 



Genus Phacodinium Prowazek. Oval; marked grooves on body 

 surface; cilia in cirrus-like fused groups; peristome long on left mar- 

 gin; cytostome posterior; contractile vacuole terminal; macronu- 

 cleus horseshoe-shape; 5-9 micro nuclei; fresh w^ater. One species. 



P. metschnicoffi (Certes) (Fig. 302, k). About 100m long. 



Genus Pseudoblepharisma Kahl. Body form intermediate be- 

 tween Spirostomum and Blepharisma; right peristomal edge with 2 

 rows of cilia; fresh water. 



P. tenuis K. (Fig. 303, h). 100-200m long. 



Genus Parablepharisma Kahl. Similar to Blepharisma; but peri- 

 stome-bearing anterior half , narrowed neck-like and pointed; ecto- 

 plasm covered with gelatinous layer in which symbiotic bacteria are 

 imbedded; salt water. 



P. pellitum K. (Fig. 303, i). 120-180/1 long. 



Genus Nyctotherus Leidy. Oval or reniform; compressed; peri- 

 stome begins at anterior end, turns slightly to right and ends in 

 cytostome located midway between the ends; cytopharynx runs 

 dorsally and posteriorly, a long tube with undulating membrane; 

 ciliary rows longitudinal and close-set; massive macronucleus in 

 anterior half with a micro nucleus; in some, nuclei are suspended 

 by a karyophore; endoplasm with discoid glycogen bodies, especially 

 in anterior region, hence yellowish to brown; contractile vacuole 

 and cytopyge terminal; in the colon of Amphibia and various 

 invertebrates. Numerous species. 



N. ovalis L. (Figs. 3; 304, a, b). Ovoid; anterior half compressed; 

 macronucleus elongate, at right angles to dorso-ventral axis at 

 anterior 1/3; micro nucleus in front of macronucleus; distinct karyo- 

 phore; glycogen bodies; QO-lSS/x by 62-95iu; giant forms up to 360iu 

 by 240m; cysts 72-106iu by 58-80^; in the colon of cockroaches. The 

 chromatin spherules of the macronucleus are often very large (p. 36). 



