S'riTI)ll^:S ON IWKASITIO l>liO'rO/OA. ' 401> 
Prowazek, S. v. — “ Die Entwickeluiio- von Herpetoiiioria s, etc..’' * Ai-I). 
a. d. kaiserl. Gesuiidli.,’ Bd. xx (1{)04), pp. 440-452, 7 text-figs. 
Weiiyon, C. M. — “Some Observations on a, Flagellate of the genus 
Cercomonas,” ‘ Quart. Journ. Mier. Sci.,’ vol. 55 (1910), pp. 
241-2G0, 19 text-figs. 
EXPLANATION OF PLATES 31 and 32, 
llhistrjitiiig Aliss D. L. Mackiimou’s paper on (a) “The 
E n e y s t m e 11 1 of II h i z o in a s t i x gracilis A 1 e x e i e 11 ; 
(b) T e tra trich o m a s t i X p ari sii n . s n b - gen . , n . sp 
[Figures drawn to scale (x 4000 ca.) under Zeiss comp. oc. 12 and 
2 mm, apochromat. Figs. 7, 8, 27, 28 and 29 are on a slightly smallei’ 
scale than the rest. The stain employed was Heidenhain's iron- 
hamiatoxylin, after fixation with sublimate alcohol.] 
Figs 1-29. Rhizomastix gracilis. 
Fig. 1. — Large pear-shaped flagellate individual, showing single long 
flagellum (FI.), “ rhizostyle ” (Rh..), basal granule of Alexeielf {B. G.), and 
large vesicular nucleus (Nu.). 
Fig. 2. — Flagellate of more spherical form. The granule at the inner 
end of the rhizostyle is well shown here {G.). 
Fig. 3. — Flagellate of which the nucleus has an eccentric karyosome. 
Figs. 4-7. — Various forms assumed by Rhizomastix gracilis. 
Note the clear zone round the nucleus, probably an artefact and due 
to shrinkage. In figs. 4, 5 and 0 the cytoplasm shows numerous 
inclusions, probably bacteria. In figs. 5 and 7 the rhizostyle has 
much the same relations to the nucleus as in Oic onion as. 
Fig. 8. — Rounded-oft individual without flagellum. Resting stage? 
Fig. 9. — Preparation for eiicystment. The flagellate rounds oft*, and 
its cytoplasm becomes more coarsely vacuolated. 
Fig. 10. — A rather later stage. The flagellum has disappeared ; the 
vacuoles become larger and fewer in number. 
Fig. II. — The cyst formed. Note the large vacuole (Fu.) and the per- 
sistent rhizostyle (Bh.). 
Fig. 12. — The nucleus sw^ells, and there is an escape of chromatin into 
the cytoplasm. 
VOL. 59^ PAKT 3. NEW SERIES. 
30 
