5 . THE PHYLUM PROTOZOA
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For detailed accounts of the ciliature, fibrillar system, and nuclear
division, see Kidder (1933c), Raabe (1936), and MacKinnon and Hawes
(1961).
Life cycle. The complete life cycle of A . mytili is not known although
certain aspects have been noted. Raabe (1936) has described its cyst
FIGS. 77-79. Ancistrum rnytili. (77) Ventral view; (78) dorsal view, mouth is seen t o
bc slightly dorsal near posterior end; (79) lateral view of right side, notice tuft of
straight tactile cilia at anterior end. C V , Contractile vacuole; P V , food vacuole;
M A , macronucleus ; M I , micronucleus. (Redrawn after Kidder, 1933a.)
which he found during the winter. These cysts are attached to the host’s
gill surfaces. The cyst wall is intimately associated with the encysted
trophozoite but is drawn out to an anterior point by which it is
attached to the host’s ctenidial tissue. MacKinnon and Hawes (1961)
have reported that trophozoites placed in a Petri dish will become