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Cap 2

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heavily armed with 
toxicysts , and \u2013 though ciliated and active \u2013 it is not 
capable of effecting extreme changes in its length; 
the non-homologous \u201cproboscis\u201d of Didinium is that 
organism\u2019s everted cytopharyngeal apparatus . 
Protargol : see Silver Impregnation Techniques . 
Proter : anterior filial product of a regular binary 
fission of the parental form ; the posterior daughter 
is the opisthe (Fig. 2.11Aa). 
Protolorica : (pl. Protoloricae ): lorica constructed 
by the proter of tintinnid spirotrichs after cytokine-
sis ; see Epilorica and Paralorica . 
Protomite : relatively brief stage in the polymorphic 
life cycle of a few ciliates (e.g., some apostomes ), 
recognizable by features of its kinetome as a sepa-
rate form between the tomont and the tomite . 
Protomont : relatively brief stage in the polymor-
phic life cycle of a few ciliates (e.g., some apostomes ), 
recognizable by features of its kinetome as a 
separate form between the feeding trophont and the 
often encysted true tomont . 
Protrichocyst : older, once popular term for muco-
cyst ; a stage in the development of a trichocyst. 
Psammophilic : literally \u201csand-loving\u201d; descriptive 
term for interstitial forms found in, on or at least 
temporarily associated with, the sands of intertidal 
zones in marine littoral biotopes or in fresh-water 
beaches and the like. 
Pseudobuccal Kinety (pl. Kineties ): an oral kinety 
that may have been derived from somatic kinety 1; 
it is an inverted kinety based on the inverted orien-
tation of its fibrillar associates; found in the Class 
 KARYORELICTEA (e.g., Loxodes ). 
Pseudolorica : an enclosure derived by allometric 
growth of the external sheath of the stalk, caused 
by very rapid secretion of outer stalk material; 
found in peritrichs , such as Opercularia . 
Pseudomembranelle : rather imprecise term used 
variously in the literature to describe oral or 
somatic ciliary complexes that seem to defy classi-
fication, but do appear to resemble some kind of 
membranelle sensu lato or complex kinetofrag-
ment ; see Frange and Pavés . 
Pseudonasse : see Rhabdos . 
Pseudoperistome : term formerly used for the vesti-
bulum of trichostomes and colpodeans . 
Pulsating Canal : see Afferent Canal . 
Pulsating Vacuole : see Contractile Vacuole . 
Quadrulus (pl. Quadruli ): buccal polykinetid
with long cilia and an infraciliary base, typically 
four kinetosomes in width and many in length; the 
lengthy rows are more loosely associated than is 
the case in peniculi and membranelles sensu stricto
(e.g., in Paramecium ); synonyms include mem-
brana quadripartita, Vierermembran, and vierteilige
Radial Canal : see Afferent Canal . 
Radial Fibers : see Postciliary Microtubules . 
Glossary 49
Radial Pins : see mention under Border Membrane . 
Reactive Budding : budding in response to stress-
ful environmental conditions. 
Recapitulation, Law of : see Biogenetic Law . 
Receiving Vacuole : see Cytopharyngeal Pouch . 
Regeneration : a process in which parts of the 
body are developed anew after loss by either natu-
ral accidents or experimental manipulations. See 
Morphogenesis . 
Reorganization Band : see Replication Band . 
Replication Band : lightly staining, though with a 
narrow Fuelgen-positive leading edge, cross-band 
of a macronucleus that migrates or sweeps along 
the length of the nucleus of spirotrichs ; in short 
macronuclei, one band and in longer macronuclei 
(e.g., in some hypotrichs) with a similar band 
traversing the other half either from midpoint 
out to the ends or from ends into the center; the 
replication band is involved in DNA replication 
and histone synthesis, the amounts of these sub-
stances doubling just behind the moving bands; 
in the homomerous macronuclei of spirotrichs , 
preceding macronuclear fission and cytokinesis of 
the organism itself; two zones may be recognized 
\u2013 the reticular (\u201cforward zone\u201d or \u201csolution plane,\u201d 
as formerly known) and the diffuse (\u201crear zone\u201d 
or \u201creconstruction plane\u201d, which is the locus of 
the DNA synthesis); an analogous (?) structure 
may also occur in the heteromerous macronucleus
of certain phyllopharyngeans where there is only 
one band, moving across the orthomere (RB, Fig. 
2.12s, 2.12t, 2.12x). 
Reproduction : note that, though there are a number 
of types of fission , the only kind of reproduction in 
ciliated protozoa is asexual , textbook statements 
notwithstanding (i.e., conjugation , for example, is 
a sexual phenomenon but not sexual reproduction); 
see Fission . 
Reticulated Fiber : see Filamentous Reticulum . 
Retractor Fibers : generalized term for bundles of 
myonemes , used to draw back some extended part 
of the body or a protruding oral region (RF, Fig. 
Retrodesma (pl. Retrodesmata ): see Retrodesmal 
Fiber . 
Retrodesmal Fiber : rarely occurring non-striated 
fiber arising close to the base of a somatic kineto-
some near its microtubular Triplets Numbers 5\u20137 
and, unlike the kinetodesma , extending posteriad 
and parallel to the pellicle (e.g., in certain cleve-
landellid armophoreans ); may be a homologue by 
positional similiarity of the kinetodesma; could be 
called a retrodesma (pl. retrodesmata) (Rd, Fig. 
2.1Ec, 2.1Ed). 
Rhabdocyst : rod-like extrusome composed of a 
shaft topped by a conical cap; on extrusion, the cap 
and distal part of the shaft remain unchanged, but 
are anchored(?) in the cell by a bulbous expansion 
of the basal portion of the organelle; found in cer-
tain karyorelicteans (Fig. 2.9Ca). 
Rhabdos : the tubular cytopharyngeal apparatus
whose walls are strengthened on the outside by 
bundles of nematodesmata and often lined longi-
tudinally both by transverse microtubules derived 
from circumoral kinetosomes and by bulge micro-
tubules whose origin is undetermined; contains 
specialized phagoplasm , sometimes with included 
toxicysts ; may be bound, near its proximal (outer) 
end, by an expansible filamentous annulus ; show-
ing a range of complexity in its own composition 
from a loose organization in some vestibulifer-
ans , which lack toxicysts, to the more elaborate 
structure in prorodontids and haptorians ; principal 
synonyms of rhabdos include pseudonasse, and 
the recently used clathrum; clathrum is here con-
sidered totally inappropriate in view of its clear 
implication of a lattice work, whereas the rhabdos 
is actually both overall, and in its principal separate 
parts, highly reminiscent of a rod or rods, thus its 
name, arranged in a straight, non-curved, encir-
cling palisade formation, with perhaps a suggestion 
of fluting; see Cyrtos (Fig. 2.7j). 
Ribbed Wall : non-ciliated lining or surface of the 
right side of the buccal cavity of many oligohy-
menophoreans , ultrastructurally, appearing ribbed 
due to the presence there of microtubular ribbons , 
presumed to be postciliary microtubules that arise 
in association with the kinetosomes of the nearby 
paroral ; considered to be naked, typically when 
no pellicular alveoli are involved posterior to the 
cytostome , thus in the cytopharynx ; considered 
to be non-naked when oral ribs are present; the 
ribbed wall on the right side is sometimes called the 
50 2. Glossary of Terms and Concepts Useful in Ciliate Systematics
primary ribbed wall, while the much rarer second-
ary ribbed wall is said to occur on the left side of 
the buccal cavity. 
Rod, Cytopharyngeal : see Nematodesma . 
Rod, Pharyngeal : see Nematodesma . 
Rootlet : any fibrillar or microtubular structure 
originating from or near a kinetosome and extend-
ing into the cytoplasm away from the pellicle ; see 
Nematodesma . 
Rosette : unique septate structure near the cyto-
stome of many apostomes ; also used to describe 
the result of several rapid preconjugation divisions 
of certain peritrich zooids in production of free-
swimming microconjugants