(Bell Animalcule Leeuwenhoek 1675; Ehrenberg '38; Dujardin '41; Stein
'51; Cl. & Lach. '58; Greeff '70; Bütschli '88; Kent '81; Stokes '88;
etc.)
Medium-sized ciliates of general bell-like form. They may be
colorless, or yellow and green through the presence of Zoochlorella.
When not contracted, the peristome end is widespread, rarely
narrowed. The adoral zone and peristome agree with the details given
in the family characteristics. The chief character is the attachment
of the posterior end by means of a single, longer or shorter, stalk,
which contains a highly contractile thread easily distinguished
in the living animal. Another character is the absence of colony
formation. Contractile vacuole, single or double, usually connected
with a sac-like reservoir. The macronucleus is invariably long and
band-formed, with attached micronucleus. Fresh and salt water.
So many species of _Vorticella_ have been described that the task of
collecting data and of arranging the synonyms is extremely irksome
and difficult. Stokes enumerates 66 species, inhabiting fresh and
salt water, and several other new species have been added since his
work. I am impressed with the fact that new species have been created
without proper regard for the manifold variations which nearly all
of the _Ciliata_ show, and I believe the 66 species might be safely
reduced to 12 or 15.
Vorticella patellina Müller. Fig. 59.
Body campanulate, widest at anterior border, from which it tapers
directly to the pedicle. The diameter of the peristome is a little
larger than the length of the body. The ciliary disk is but little
elevated. The cuticle is not striated and the body plasm is quite
transparent. Length 52µ.
[Illustration: Fig. 59.--_Vorticella patellina_.]
Vorticella marina Greeff. Fig. 60.
The body is conical but variable, and may he short or elongate, so
that relative length and breadth offer no chance of identification.
In general the body is campanulate. The distinguishing feature is the
transverse annulation of the bell.
Small, but common, and grows in small social groups. Length 35µ.
[Illustration: Fig. 60.--_Vorticella marina_.]
Genus ZOOTHAMNIUM (Bory de St. Vincent 1824) Stein '38, '54.
Colorless and highly contractile forms growing in small or large
colonies. The form and structure of the individuals is not different
from _Vorticella_. The colonies are usually richly branched upon
the dichotomous plan and the entire colony is contractile. The main
character is that with each division of the individual the stalk
also divides, each daughter cell getting one-half of the parent stem.
The stems therefore remain in communication, so that a simultaneous
contraction results, and the colony as a whole is withdrawn. In some
species so-called macrogonidia, or larger sexual individuals, are
developed alongside the usual ones. Fresh and salt water.
Zoothamnium elegans D'Udekem '64? Fig. 61.
The bodies are variable--peristomial border widely dilated, tapering
and attenuate posteriorly. The pedicle is slender, smooth, and
transparent, and branches sparsely at its distal extremity. There
are but few zooids (3 to 4). The ciliary disk projects conspicuously
beyond the peristomial border. The pharyngeal cleft is very distinct
and extends beyond center of body. Length of body 80µ.
[Illustration: Fig. 61.--_Zoothamnium elegans_.]
Genus COTHURNIA (Ehr. '31) Clap. & Lach. '58.
Colorless forms of medium size-in some cases they may be green
by Zoochlorella. The general structure is similar to that of
_Vorticella_, but the individuals are elongate and occupy houses. The
macronucleus is invariably long and band-form. The distinguishing
character is the colorless or brownish lorica of quite variable form
but always attached. These houses may be finger-formed, with widened
center, or widened mouth, or constricted mouth, and the like.
Ring-formed swellings are frequently developed. Sometimes the mouth
becomes twisted and the lorica is therefore bilateral. The houses
are attached either directly to some foreign object or by means of
a short stalk. The animals are similarly fastened to the lorica,
sometimes directly, sometimes by means of a short stalk. When they
contract they draw back to the bottom of the lorica; when expanded
they usually stretch out of the mouth opening. In some forms there
is an operculum, by means of which the opening of the shell can be
closed when the animal is retracted. Fresh and salt water.
The number of species of _Cothurnia_ has become so great that the
difficulty in placing forms is almost sufficient to discourage the
systematist; as Bütschli well remarks, the variations in the theca
have been made the basis of new species so many times that the
genus is almost as confused as _Difflugia_ among the rhizopods or
_Campanularia_ among the hydroids. The length of cup, of stalk,
the presence of annulations on stalk or cup, etc., have given rise
to many specific names, the majority of which I believe can be
discarded. According to such differentials the same branch of an alga
holding a hundred specimens of _Cothurnia crystallina_ yield 10 or 12
species, whereas they are merely growth stages of one and the same
form.
Cothurnia crystallina Ehr. Fig. 62.
Synonyms: _Vaginicolla crystallina_ Ehr., Perty, Eichwald; _V.
grandis_ Perty; _V. pedunculata_ Eichwald; _Cothurnia crystallina_
Claparède & Lachmann, D'Udek.; _C. gigantea_ D'Udek; _C. maritima_,
_C. crystallina_ Cohn; _C. grandis_ Meresch.
The form of the cup shows the greatest differences; sometimes it is
cylindrical, sometimes elongate thimble-shape, sometimes pouch-shape,
corrugated or smooth on the sides, and wavy or smooth on border.
Frequently the basal part becomes stalk-like, but this is very short.
When present, the stalk may or may not have a knob-like swelling. The
animal within the cup may or may not be borne on a stalk, and this
stalk may or may not be knobbed. The cups are colorless or brown. The
animal is very contractile and may stretch half its length out of the
cup or retract well into it. There is no operculum. The length of the
cup varies from 70µ to 200µ (_C. gigantea_; _Vag. grandis_, etc.).
From Entz.
There is nothing to add to Entz's characterization of this species,
which is found both in fresh and salt water. The variability of the
cup and stalk is quite noticeable in the Woods Hole forms.
[Illustration: Fig. 62.--_Cothurnia crystallina_.]
Cothurnia imberbis Ehrenberg, var. curvula Entz. Fig. 63.
Synonyms: _C. imberbis_ Kent et al.; _C. curvula_ Entz; _C. socialis_
Gruber?
The lorica is swollen posteriorly, narrowest at the oral margin, bent
on its axis and is supported on a short stalk. It is perfectly smooth
and without annulations. The animal itself has no definite stalk.
When fully expanded the animal emerges but slightly from the margin
of the cup. Fresh and salt water. On red algæ. Dimensions of Woods
Hole form: Cup 50 to 55µ long; greatest diameter 22µ; length of stalk
4 to 5µ.
[Illustration: Fig. 63.--_Cothurnia imberbis_.]
Cothurnia nodosa Claparède & Lachmann. Fig.64.
A. Smooth cup.--_Cothurnia maritima_ Ehr., Eichwald, Stein, Kent.
B. Cross-ringed cup.--_C. pupa_ Eichwald, Stein, Cohn; _C. nodosa_
Cl & L.; _V. crystallina_ Entz '78; _C. pontica_ Meresch.,
Kent; _C. cohnii_ and _pupa_ Kent; _C. longipes_ Kellicott '94.
The cup is elongated, swollen centrally, tapering at oral end
and conical at base or rounded. Oral opening either circular or
elliptical. Cross rings may or may not be present, and the cup is
either smooth or annulate. Length of cup 70µ to 80µ. The stalk which
supports the cup is extremely variable in length. The animal is borne
upon a stalk of variable length within the cup.
Entz states that the many variations which this species exhibits run
into each other so gradually that he does not believe it wise to
separate them. The Woods Hole forms which I found on algæ of various
kinds were nearly of a size, and did not vary much from the one
figured. Kellicott '94 described a _Cothurnia_ from Woods Hole under
the name of _C. longipes_, which I believe is only a long-stemmed
variety of _C. nodosa_. My form has the following dimensions: Cup
75µ; cup stalk 38µ; animal stalk 14µ.
[Illustration: Fig. 64.--_Cothurnia nodosa_.]