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ZOOLOGY 
Cuass IV. Acinetaria. 
No cilia or flagella present, but a number of tentacular 
processes, which may be adhesive or may be tubular and 
suctorial. The Acinetaria are usually fixed, and most com- 
monly stalked (Fig. 26). The nucleus is single, and often 
branched. One or more contractile vacuoles occur. Repro- 
duction takes place by binary fission and gemmation ; the latter 
is often internal. 
The Acinetaria are either marine or freshwater, and they 
are all carnivorous, living chiefly on the soft parts of Infusoria. 
Fic. 25.—Sphaerophrya magna, Maupas. x 300. 
1. Individuals of Colpoda parvifrons, a ciliated Infus- 
ra) orian whose soft parts are being sucked up by the 
Sphaerophrya. 
2. The nucleus, 
\ 3. One of the hollow tentacles ending in a knob. 
: r=5--3 
i i) 
The cuticle may be thin, but in some cases a definite mem- 
branous capsule is formed. Two kinds of tentacles may be 
found: one long and adhesive, whose function is to catch and 
hold the prey; the other is shorter, tubular, and ends in a 
sucker,—these latter are sometimes provided with a spiral 
thickening. The soft protoplasm of Infusoria, on which they 
prey, 1s sucked up through these hollow tentacles (Fig. 25). 
Dendrocometes has a round body, from which four to six many- 
branched stout arms project. Each branch ends in a point, 
which is said to be hollow, and by means of which food is 
sucked into the body. In this genus, and in one or two others, 
the contractile vacuole has an excretory duct. 
Acineta (Fig. 26) is a stalked form with a membranous 
cup; the tentacles are arranged in two clusters at each side of 
the body. 
teproduction may be by fission, or by external gemmation, 
or by internal gemmation, in which case a brood - pouch is 
formed, which may be open, but is more commonly closed. 
