The Sarcodina 243 



Fig. 5. 29. A, B. Lecquereiisia spiralis (Ehrbg.) Penard (test, 125-140(14 

 long); oral view, showing surface pattern (A); optical section (B), schematic 

 (after P.). C-F. Arcella vulgaris Ehrenberg (test, 80-140;u in diameter); 

 horizontal section (C), schematic (after Penard); optical section through 

 wall of test (D), schematic (after Awerinzew); vertical section (E) through 

 test (after Penard); surface pattern (F), schematic (after Awerinzew). G. 

 Euglypha aspera Penard, plates shown at margin and around mouth; x206 

 (after P.). H, I. Plates from mouth region and from other parts of test 

 (after P.). J. Stained section of Heleopera rosea (test 90-105/i, long), show- 

 ing test membrane with overlying plates; reserve plates in cytoplasm 

 (after MacKiniay). K. Test of Centropyxis aculeata Stein, spineless variety 

 (C. ecornis); xlOO (after Leidy). L. Amphizonella violacea Greef (test 125- 

 250^ long); chitinous test covered with a gelatinous layer which is often 

 lacking (after Penard). 



well-developed chromidium, it was assumed that the chromidia had been 

 utilized for reconstitution of the normal nuclei. 



In addition to the usual inclusions, non-contractile vacuoles supposedly 

 filled with gas are frequently seen in species of Arcella. It has been sug- 

 gested that these vacuoles function in flotation by increasing the buoyancy 

 of the organism (8). 



