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spongy appearance (i.e., the spongiome), found 
in the vicinity of the contractile vacuole , function-
ing to collect fluid for elimination. 
Springborsten : see Saltatorial Cilia . 
Stalk : term broadly used for any kind of cylindri-
cal and generally tubular supporting structure, 
either totally non-living or with a non-living 
sheath or annulus , running from the posterior 
end of a ciliate’s body to a point of fixation on 
the underlying substratum; typically found in 
attached, sedentary or sessile forms or stages, 
with or without involvement of a lorica, serving 
as an attachment or holdfast organelle ; may be of 
varying length, composition, and origin; produced 
with involvement of secretory ampullae , kineto-
somes , and/or pellicular pores ; may be contractile 
with a spasmoneme or non-contractile; ramified 
in some groups, associated with colonial organi-
zation of the supported zooids ; most commonly 
54 2. Glossary of Terms and Concepts Useful in Ciliate Systematics
known in chonotrichs , suctorians , and peritrichs , 
but undoubtedly is a non-homologous structure 
in these diverse taxonomic groups; see Peduncle
(St, Fig. 2.11B, 2.11C). 
Statocyst : see Concrement Vacuole and Müller’s 
Vesicle . 
Statolith : see Concrement Vacuole and Müller’s 
Vesicle . 
Stentorin : “blue” cytoplasmic pigment distributed 
in pigmentocysts and appearing in longitudinal 
rows in certain species of the heterotrich Stentor . 
Stereocilum (pl. Stereocilia ): see Clavate Cilium . 
Stichodyad : type of paroral whose infraciliature 
is composed of dikinetids so oriented that each 
is perpendicular to the anteroposterior axis of the 
paroral ; these kinetosomes are often arranged in 
a zigzag pattern with only the outer kinetosomes 
being ciliferous ; common condition in oligohy-
menophoreans ; see Haplokinety , Stichomonad . 
Stichomonad : type of paroral whose infraciliature 
is composed of a single file or line of identically 
oriented kinetosomes ; the characteristic condition 
found in many spirotrichs ; see Diplostichomonad , 
Stichodyad . 
Stock : now seldom-used term referring to any 
named or numbered clone that is maintained in 
culture separately from other such isolates. 
Stomatogenesis : literally “mouth-formation”; in 
the broadest sense, this dynamic phenomenon 
embraces neoformation or replacement of all oral 
structures and infrastructures and any associated 
openings, depressions or cavities in both the proter
and opisthe , typically prior to and during binary 
fission ; major kinds or modes are now recognized 
(see Apokinetal , Buccokinetal , Mixokinetal,
Parakinetal , and Telokinetal ), under which the 
names of older descriptive categories are gener-
ally listed, as synonyms; oral replacement , a 
stomatogenic phenomenon that may occur peri-
odically, refers to the in situ remodeling of the 
parental oral structures or their total substitution 
by new organelles, because of the partial or com-
plete dedifferentiation or resportion of the former 
ones; reversible microstome-macrostome transforma-
tion , a special kind of oral replacement, involves 
the growth and/or replacement of a small oral 
apparatus with a greatly enlarged one or vice 
versa (e.g., in some species of Tetrahymena ); see 
Somatogenesis (Fig. 2.11D). 
Stomatogenic Field : general term for the group 
of kinetosomes , non-ciliferous throughout most of 
the process, actively involved – as the anlage – in 
the production of new oral ciliature by any of the 
described modes of stomatogenesis ; see Anarchic 
Field , Germinal Row , and Scutica (SF, Fig. 
Stomatogenic Kinety (pl. Kineties ): see Kinety
Number 1 and Parakinetal ( stomatogenesis ) (SK, 
Fig. 2.11Dd). 
Stomatogenous Meridian : an older term for sto-
matogenic kinety . 
Strain : a named clone of a particular species of cil-
iate that usually differs in minor ways (e.g. genetic, 
phenotypic, physiological) from other strains. 
Stria (pl. Striae ): a beaded, longitudinal cytoplasmic 
strand found beneath the perilemma in the oral polyki-
netids of some spirotrichs , especially tintinnids . 
Striated Bands : name for a (micro)fibrillar system 
discovered to lie just below the epiplasm in some 
ciliates (e.g., Paramecium ). 
Strobilation : kind of multiple fission in which 
successive tomites or buds are fully or partially 
separated or pinched off, sometimes within the 
confines of a cyst and usually resulting in a tem-
porary linear chain of small individuals requiring 
subsequent metamorphosis to regain the form typi-
cal of the normal trophont stage of the life cycle; 
see Catenoid Colony (Fig. 2.8Ba). 
Structural Conservatism Hypothesis : mainte-
nance (i.e., conservation) of a structure through 
time is inversely related to the level of its biologi-
cal organization; in the evolution of ciliates, then, 
among the most stable and most conservative 
taxonomic characters would be those involving 
unit organelles , ultrastructures at a relatively low 
organizational level (e.g., the various microtubular 
ribbons and kinetodesma associated with monoki-
netids and dikinetids). 
Structural Guidance, Principle of : positioning and 
orientation of newly arising organelles (e.g., kineto-
somes on the surface) under the localized influence 
of nearby pre-existing structures; see Cytotaxis . 
Glossary 55
Style : see Stylet . 
Stylet : variously used, but generally as a synonym 
of podite . 
Stylus : see Stylet . 
Subkinetal Microtubules : one or more microtubu-
lar ribbons running under the proximal ends of kine-
tosomes in phyllopharyngeans (e.g., Brooklynella ); 
compare to Basal Microtubules . 
Subpellicular Microtubules : microtubules , single 
or in ribbons, in or just under the pellicle and cours-
ing along parallel to the outer surface of the cell; 
originate either independently from kinetosomes 
(e.g., longitudinal microtubules ) or may be exten-
sions of transverse or postciliary microtubules . 
Sucker : variously used, but generally for the cup-
shaped concavity forming the often non-homologous
thigmotactic area or adhesive organelle in scattered
species belonging to quite different taxa (e.g., 
 astomes , clevelandellids , licnophorids , peritrichs , 
 thigmotrichs ); also used to denote the sucking tube
of rhynchodids; may be rich in fibrils, polysac-
charide plaques or thigmotactic cilia ; a rare syno-
nym, for protozoa, is acetabulum; see Attachment
Organelle (S, Fig. 2.9B). 
Sucking Tentacle : see Suctorial Tentacle . 
Sucking Tube : apically located, complex septate 
structure composed of microtubular ribbons , the 
phyllae , and serving as the ingestatory apparatus 
of rhynchodids and grossglockneriid colpodeans 
(Fig. 2.10f). 
Suctorial Organelle : see Suctorial Tentacle . 
Suctorial Tentacle : extensible and retractable 
tubular extension of the body of suctorians , con-
taining a complex array (set or sets) of longitu-
dinally arranged microtubular ribbons or phyllae
and equipped both with haptocysts at its often 
capitate tip and vesicles functioning in formation 
of food vacuolar membrane; the tentacle serves for 
prey capture but is also the organism’s ingestatory 
apparatus, analogous, if not homologous, with the 
cytostome-cytopharyngeal complex of other phyllo-
pharyngeans ; ranging from one in number to many, 
their grouping in fascicles on the body, whether 
on actinophores or not, is often of taxonomic sig-
nificance; the larval or bud stages in suctorian life 
cycles possess none, as a rule; a type of extremely 
short, non-extensible tentacle, the endosprit , is 
known in several families (e.g., Cyathodinium ) 
(SuT, Figs. 2.8i, 2.11Cd; 2.10a–2.10e). 
Supernumerary Kinetosomes : apparently “extra” 
ciliferous or barren kinetosomes observed in vari-
ous instances, in more than one stage in the life 
cycle, in differing but specific locations on the