Part 44

Below the thorax there is an annular circle that joins the thorax to the abdomen; this is considerably the largest part of the animal, and contains the stomach and viscera. When full of food, the intestines are opake, and of a crimson colour, extending from the thorax quite through the abdomen and a great part of the tail, exhibiting a fine view of the peristaltic motion, or those gradual contractions and dilatations of the intestines, which propel their contents downwards. Numerous ramifications of vessels, both longitudinal and transverse, surround the intestines. The abdomen is not only capable of contraction, but also admits of such a degree of extension, as to form a case for all the other parts of the body. The tail extends from a joint at the lower part of the belly to the posterior extremity; it is of a tapering form, and consists generally of three joints; when the animal is inclined to fix itself to any thing by the tail, it thrusts out four, sometimes six, little hooks from the extreme part; these are placed in pairs, one at the very extremity itself, the other two a little way up the sides; the three pair are seldom seen at the same time. The wheels appear to be the organs used by the animal to assist it in swimming.

All the actions of this creature seem to imply sagacity and quickness of sensation; at the least touch or motion in the water, they instantly draw in their wheels. Baker conjectures that they have eyes lodged near the wheels, because while they are in the globular or maggot state, their motions are slow and stumbling; but after the wheels are protruded, they are performed with great regularity, swiftness, and steadiness. Can we sufficiently admire the wonderful contrivance in the apparatus of this animal? a being so diminutive, as not to exceed in size a grain of sand!

Plate XXVI. Fig. 17, represents the wheel animal in what Baker calls the maggot state; while in this form small spiculæ are seen to dart out near the anterior part; the snout is sometimes more, at other times less acute than in this delineation. _a_, a small horn near the thorax.

Fig. 15 represents its manner of moving from place to place, while in the maggot state. _a_, the projecting horn.

Fig. 12 exhibits it with the two semicircular parts, _a a_, protruded, and in the posture in which it places itself, when preparing to swim about, or going to set its wheels in motion.

Fig. 1 shews the head at its full extent, and a couple of small bodies, _a a_, on the top of it, armed with small teeth, _b_, like those of the balance-wheel of a watch.

At Fig. 18 the interior parts are more particularly exhibited. _a_, the circle from which many vessels originate; _b_, the thorax or breast, joined to the head by the neck, _c_; the part which is supposed to be the heart is plainly seen at _d_; the abdomen, _f_, is separated from the breast by a ring, _e_; _g_, the tail.

Fig. 19 exhibits the animal not fully extended, though with its wheels in motion.

Fig. 20 shews it with its side towards the eye; in this position one of the wheels, _a_, appears to lie considerably below the other.

Fig. 6 and 16 represent two of these creatures in the postures in which they are frequently seen when the wheels are not protruded, but with the fibrillæ, _a b_, vibrating quickly.

Fig. 2 exhibits the animal with the body nearly drawn into the abdomen; at Fig. 21, the body still further drawn in; at Fig. 22, as it appears with the tail partly drawn in; at Fig. 23, in a globular form, but still adhering by the tail.

Sometimes, when in the maggot form, it rolls its head and tail together, without drawing them into the body; as represented at Fig. 14.

Baker has also described three other species, one of which, differing only from the preceding in having a very long tail, is represented at Fig. 7.

Fig. 11 is another kind, with crustaceous spiculæ, _b_, at the fore-part; within this, at _c_, an opake oval body may be seen, which has been taken for an egg.

Fig. 3 is another kind; it has two projecting points, _a a_, from the tail, and the head furnished with a number of fibrillæ, _b b_.

Fig. 13 represents another species, described by Spallanzani.

Plate XXVII. Fig. 46, 47, 48, 49, represent the wheel animals seen and delineated by Müller. _a_, the head; _b_, the eyes; _c_, a small horn; _d_, the rotatory organ; _e_, the tail; _f_, the points of the tail.

324. VORTICELLA FURCATA. V. cylindrica, apertura integra, cauda longiuscula bifida. Cylindrical vorticella, the aperture undivided, the tail rather long, and divided into two parts.

A cylindric body with a rotatory organ, consisting of a row of hairs at the apex; the tail is divided into two parts turning a little inwards. When at rest, it joins the segments of the tail; but opens them when in motion. It is generally found in common water.

325. VORTICELLA CATULUS. V. cylindracea, apertura mutica, cauda perbrevi, reflexa, bicuspi. Plate XXVII. Fig. 50. Cylindrical vorticella, the aperture plain, the tail short, bent back, and divided into two points.

It is a little thick muscular animalculum, folding itself up; of an equal breadth throughout, the body disfigured by longitudinal folds winding in various directions; the anterior part or head is connected to the body by a little neck, and it occasionally exhibits a very minute rotatory organ. The tail, _e_, is short, terminating in two very small bristles, _d_, which are exposed or concealed at pleasure; the intestines ill-defined. Its motion is rotatory, but in different directions. It is commonly found in marshy waters.

326. VORTICELLA CANICULA. V. cylindracea, apertura mutica, cauda brevi, articulata, bicuspi. Cylindrical vorticella, the aperture plain, with a short articulated tail divided into two pointed parts.

327. VORTICELLA FELIS. V. caudata, cylindracea, mutica, cauda spinis duabus longis terminata. With a tail, cylindrical, beardless, the tail terminating in two long spines.

The body is large, the apex of an equal thickness, obtuse, with rotatory filaments; the tail acute, with two pellucid spines, in length about one-third part of the body, alternately separating from and approaching each other.

328. VORTICELLA STENTOREA. V. caudata, elongata, tubæformis limbo ciliato. Long-tailed vorticella, trumpet-shaped, the arms furnished with rows of short hairs. See this fully described by the name of hydra stentorea, in page 392.

329. VORTICELLA SOCIALIS. V. caudata, aggregata, clavata; disco obliquo. A description of this vorticella has also been given, as hydra socialis, in page 395.

330. VORTICELLA FLOSCULOSA. V. caudata, aggregata, oblongo-ovata, disco dilatato pellucido. Plate XXVII. Fig. 51 and 52. With a tail aggregated, of an oblong oval shape, with a dilated pellucid disc.

To the naked eye it appears as a yellow globule, adhering to the ceratophyllum, or common horn-wort, Fig. 52, _a_, like a little flower; or a heap of yellow eggs, _b_. With the assistance of the microscope they are discovered to be a congeries of vorticellæ, constituting a sphere from a mouldy center. They contract or extend their bodies either when alone or associated, and excite a vortex in the water by means of the disc. When they quit the society, and act singly, their parts may be more readily distinguished, and will be found to consist of a head, abdomen, and tail. The head is often drawn back so far into the abdomen, that it cannot be seen, exhibiting only a projecting, broad kidney-shaped disc. The abdomen, Fig. 51, _d_, is oblong, oval, and pellucid, replete with obscure intestines, amongst which are one or two remarkable black oval spots, _e_; the tail, _f_, is sharp, twice as long as the abdomen, either rough and annulated, or altogether smooth.

331. VORTICELLA CITRINA. V. simplex, multiformis, orificio contractili, pedunculo æquali. Plate XXVII. Fig. 53. Simple, many-shaped, with an orifice admitting of contraction, and equal-sized foot-stalk.

The head is full of molecules, round, everywhere of an equal size, and very pellucid; both sides of the orifice are ciliated, and each has a rotatory motion, appearing sometimes without the edge of the mouth, as at _a a_; at other times within it. No distinct intestines or internal motion are perceivable. Its motion is different from most of this genus, but not easily described; at _c c_ are small feet. It is found in stagnant water.

332. VORTICELLA PIRIFORMIS. V. simplex, obovata, pedicello minimo retractili. Simple, somewhat oval, with a very small retractile foot, which it can draw within itself.

333. VORTICELLA TUBEROSA. V. simplex, turbinata, apice bituberculata.

Simple vorticella, the upper part broad, the under part small, with two projections at the anterior end, furnished with a number of fibrillæ, which produce a current of water by their vibration, and thus collect food for the animal. Baker has delineated it in Plate XIII. No. 10, 11, 12, of his Employment for the Microscope.

334. VORTICELLA RINGENS. V. simplex, obovata, pedunculo minimo, orificio contractili. Simple, somewhat of an oval shape, with a small pedicle, and an orifice which it contracts or dilates.

The small head, or rather body of this little creature is pear-shaped, pellucid, the middle of the aperture convex, both sides ciliated, the pedicle four times shorter than the body; it can contract the orifice to an obtuse point.

335. VORTICELLA INCLINANS. V. simplex, deflexa, pedunculo brevi, capitulo retractili. Simple, bent, with a short pedicle, and small retractile head.

This has a pellucid pendulous little head; the anterior part truncated, occasionally contracting itself twice as short as the pedicle; its shape resembles that of a tobacco-pipe.

336. VORTICELLA VAGINATA. V. simplex, erecta, ovato-truncata, pedunculo vaginato. Simple vorticella, erect, of the shape of a truncated egg; the pedicle is contained in a sheath.

For the 337th, 338th, and 339th, the author refers to the Zool. Dan. he terms them, vorticella cyathina, vorticella putrina, vorticella patellina.

340. VORTICELLA GLOBULARIA. V. simplex, sphærica, pedunculo retortili. Simple, spherical, with a twisted pedicle.

This animalculum has a small spherical head, the aperture of the mouth ciliated; the pedicle four times longer than the body, which it contracts into a spiral form. It is frequent among the cyclopa quadricorni.

341. VORTICELLA LUNARIS. V. simplex, hemisphærica, pedunculo retortili. Plate XXVII. Fig. 54. Simple, hemispherical, with a twisted pedicle.

The small head of this animalculum is goblet-shaped, the margin of the orifice protuberant, ciliated on both sides, with undulating hairs; the pedicle eight or ten times the length of the body. The pedicle extends itself as often as the mouth is opened, but is twisted up spirally when it is shut; and these motions are frequently repeated in a short space of time, _a a_, the head when expanded; _b_, when shut; _c_, the undulated edge; _d d_, the cilia erect; _e_, when horizontal; _f_, the pedicle when straight; _g_, when bent in a spiral form.

342. VORTICELLA CONVALLARIA. V. simplex, campanulata, pedunculo retortili. This animalculum, the bell-animal of Baker, has been fully described in page 407.

343. VORTICELLA NUTANS. V. simplex, turbinata, pedunculo retortili. Simple, with a twisted turbinated pedicle.

The pedicle is simple, and twists itself spirally; is extremely slender, with a kind of cap on its head; the margin white and round, and appearing as if encompassed with a lucid ring; the head diminishes towards the base. It is transparent.

344. VORTICELLA NEBULIFERA. V. simplex, ovata, pedunculo reflexili. Plate XXVII. Fig. 66. Simple, egg-shaped, the pedicle bent back.

The body is narrow at the base, open and truncated at the top; the margin apparently surrounded with a ring; but, when the aperture is shut, the animalculum is egg-shaped, with a simple setaceous pedicle, considerably longer than the body, and generally much bent back. _a a a_, the head open; _b_, partly closed; _c_, quite shut; _d_, the stalk when straight; and at _e_, when bent.

345. VORTICELLA ANNULARIS. V. simplex, truncata, pedunculo apice retortili. Simple, truncated, with a pedicle twisted at the end.

This is visible to the naked eye; when contracted, it appears to be annulated; the head is an inverted cone, convex when the mouth is shut, but truncated when it is open, and with a protuberant edge; the pedicle is simple, very long and thick, whiter at the top than any other part, and formed into a little head; the apex is twisted spirally.

346. VORTICELLA ACINOSA. An ample description of this animalculum, under the title of vorticella umbellaria, has been given in page 402.

347. VORTICELLA FASCICULATA. V. simplex, viridis, campanulata, margine reflexo, pedunculo retortili. Simple, green, bell-shaped, the margin or edge turned back, the pedicle twisted.

The head is bell-shaped, green, opake, narrow at bottom, pellucid. It has a rotatory organ, which may sometimes be seen projecting beyond the aperture; there is a little head at the apex, and the pedicle is twisted and very slender. A congealed green mass, which is often swimming about in ditches, is composed of myriads of these animalcula, which are invisible to the eye, but when magnified, appear like a bundle of green flowers.

348. VORTICELLA HIANS. V. simplex, citriformis, pedunculo retortili. This may be classed among the most minute. The head resembles a citron, the apex is truncated, the base narrow; a gaping cleft is observable descending from the apex, to one-third of the body.

349. VORTICELLA BELLIS. V. simplex, hemispherica, margine contractili. Simple, hemispherical, with a margin which it can contract at pleasure.

The body is of a yellow colour, much resembling the flower of a daisy; the head scarcely pellucid; the internal part quite filled; it is abundantly ciliated round the margin, moving in a rotatory manner.

The foot or pedicle is long, slender, and pellucid; it is divided into two parts, with small knobs on the top of each; the base adheres to a bulb, the under-part is covered with small scales.

350. VORTICELLA GEMELLA. V. simplex, sphærica, capitulo gemino. Simple, spherical, with a double head.

The pedicle is long, and constantly furnished with two small heads at its apex; these are bright and clear.

351. VORTICELLA PYRARIA. The distinguishing characters of this animalculum will be found at page 400.

352. VORTICELLA ANASTATICA. A full description of this vorticella has also been given at page 397.

353. VORTICELLA DIGITALIS. At page 406 the reader will likewise meet with an account of the v. digitalis.

354. VORTICELLA POLYPINA. V. composita, ovato-truncata, pedunculo reflexili ramosissimo. Plate XXVII. Fig. 61. Compound vorticella, oval, truncated, with a bending branching stalk.

When viewed with a small magnifier, they appear like so many little trees; the upper part or heads are egg-shaped, the top truncated, the lower part filled with intestines; the branches are thick set with little knobs. _a_, the trunk; _b b b_, the branches; _c c_, the head when extended; _d_, the small knobs on the branches.

355. VORTICELLA RACEMOSA. V. composita, pedunculo rigido, pedicellis ramosissimis longis. Compound, rigid pedicle, with small branched long feet.

To the naked eye it appears like the vorticella socialis, described in page 395, but is distinguished from it by always adhering to the sides of the vessel in which it is placed. With the microscope, a long very slender pedicle is discovered sticking to the sides of the vessels, from which proceed an innumerable quantity of crystalline pellucid pearls, which, together with the stalk, are variously agitated in the water. They sometimes move separately, at other times together, are sometimes drawn down to the root, and in a moment expanded again.

XVII. BRACHIONUS.

Vermis contractilis, testa tectus, ciliis rotatoriis. A worm capable of contracting, covered with a shell, and furnished with rotatory cilia.

356. BRACHIONUS STRIATUS. B. univalvis, testa ovata striata, apice sexdentata, basi integra, cauda nulla. Plate XXVII. Fig. 64 and 65. Univalved brachionus, the shell oval and striated, six notches or teeth round the upper edge, the base whole or even, without a tail.

The shell is oblong, pellucid, and capable of altering its figure. The apex, _a_, is truncated, with six small teeth on the edge of it, twelve longitudinal streaks down the back, the base obtuse and smooth. The teeth are occasionally either protruded or retracted; on the other side of the shell, towards the tail, there are two little spines or horns, _c_.

The animalculum itself is muscular, pellucid, and crystalline, often of a yellow colour; from the apex it now and then puts forth three little bundles of playing hairs, the two lateral ones shorter than the middle one; a forked deglutatory muscle, _e_, is perceptible; and on the under side, when the apex is drawn in, two rigid points may be discovered. It is found in sea water.

357. BRACHIONUS SQUAMULA. B. univalvis, testa orbicularis, apice truncata quadridentata, basi integra, cauda nulla. Univalved brachionus, with an orbicular shell; the apex truncated, and having four teeth, the base smooth, no tail.

358. BRACHIONUS PALA. B. univalvis, testa oblonga excavata, apice quadridentata, basi integra, cauda nulla. Univalved brachionus, with an oblong excavated shell, four long teeth at the apex, the base smooth, no tail. It is of a yellow colour.

359. BRACHIONUS BIPALIUM. B. univalvis, testa oblonga inflexa, apice decemdentata, basi integra, cauda spuria. Univalved brachionus, the shell oblong and inflected, ten teeth at the apex, the base smooth, and a spurious tail.

360. BRACHIONUS PATINA. B. univalvis, testa orbiculari integra, cauda mutica. Univalved brachionus, with an orbicular shell, the edges regular, and having a long beardless tail.

The patina is extremely bright and splendid; it has a large body, a crystalline and nearly circular shell, without either incision or teeth, though towards the apex it falls in so as to form a smooth notch; the body is affixed to the middle of the shell; a double glittering organ, with ciliated edges, is projected from the apex; both these organs are of a conical figure, appearing to stand on a pellucid substance, which is divided into two lobes; between these and the rotatory organ there is a silver-coloured crenulated membrane; two small claws may be discovered near the mouth. It is reckoned as one of the rarer species of vorticella, and is found in stagnant waters in the month of May.

361. BRACHIONUS CLYPEATUS. B. univalvis, testa oblonga, apice emarginata, basi integra, cauda mutica. Univalved brachionus, the shell oblong, the apex notched, the base smooth, and the tail naked.

362. BRACHIONUS LAMELLARIS. B. univalvis, testa producta, apice integra, basi tricorni, cauda bipili. Univalved brachionus, the shell extending considerably beyond the body; the base divided into three small horns, with two hairs at the end of the tail.

363. BRACHIONUS PATELLA. B. univalvis, testa ovata, apice bidentata, basi emarginata, cauda biseta. Brachionus with a univalve oval shell, two teeth at the apex, the base notched; two bristles at the tail.

The shell plain, oval, orbicular, crystalline, with the anterior part terminating in two acute points on both sides, though the intervening space is commonly filled up with the head of the animal. The head, the tail, and the trunk are very distinct; the bottom of the trunk is terminated in a semicircle, the fore-part marked with two transverse lines; it occupies the disc of the shell. The intestines are indistinct, and the tail affixed to the trunk; it is short, annulated, flexible, the middle projecting beyond the shell, the apex diverging into two very fine bristles; it fastens itself by these, and whirls about with the body erect; the rotatory cilia are not perceptible without great difficulty. It is found in marshy water all the winter.

364. BRACHIONUS BRACTEA. B. univalvis, testa suborbiculari, apice lunata, basi integra, cauda spina duplici. Univalved brachionus, the shell rather orbicular, lunated apex, smooth base, and the tail furnished with two spines.

365. BRACHIONUS PLICATILIS. B. univalvis, testa oblonga, apice crenulata, basi emarginata. Univalved brachionus, with an oblong shell, the apex hairy, and the base notched.

366. BRACHIONUS OVALIS. B. bivalvis, testa depressa, apice emarginata, basi incisa, cauda cirro duplici. Bivalved brachionus, with a flattened shell, the apex notched, a hollow part at the base, the tail formed of two tufts of hair.

367. BRACHIONUS TRIPOS. B. bivalvis, testa apice mutica, basi tricorni, cauda duplici. Plate XXVII. Fig. 59. Bivalved, the apex of the shell beardless, three horns at the base, and double tail.

The body is pellucid, nearly triangular, bivalved, and open on the back of the animalculum; from the orifice proceed two little laminæ larger than the rotatory cilia; at the bottom are three or four rigid points, _e f e_, and a moveable tail, _g_, between them, divided into two filaments, which the little creature opens and shuts at pleasure; by these it fixes itself to objects. _a a_, the lateral cilia; _b_, two small laminæ; _c_, a deglutatory muscle; _d_, an opake mass.

368. BRACHIONUS DENTATUS. B. bivalvis, testa arcuata, apice et basi utrinque dentata, cauda spina duplici. Bivalved brachionus, with an arched shell; the apex and the base are both toothed, and the tail formed of two spines.

369. BRACHIONUS MUCRONATUS. B. bivalvis, subquadrata, apice et basi utrinque mucronata, cauda spina duplici. Bivalved, somewhat of a square form; the base and apex pointed; the tail consisting of two spines.

370. BRACHIONUS UNCINATUS. B. bivalvis, testa ovali, apice integra, basi mucronata, cauda rugosa biseta. Plate XXVII. Fig. 55. Bivalved brachionus, with an oval shell, the apex even, the base pointed, two thick bristles for the tail.

This is one of the smallest bivalved animalcula, muscular, the apex and anterior part round, the hinder part straight, terminating in a point, furnished with a hook on the fore-part, a small rotatory organ, a long tail composed of joints, and divided at the end into two bristles. It can open its shell both at the fore and hind-part. _a_, the shell when close; _c_, the posterior point; _d_, the animalculum; _h_, the tail; _i_, the bristles.

371. BRACHIONUS CIRRATUS. B. capsularis, testa apice producta, basi curti bicorni, cauda biseta. Larger than the preceding, ventricose, somewhat pellucid, the head conical, with a bundle of hairs on both sides; it has likewise a rotatory organ.

372. BRACHIONUS PASSUS. B. capsularis, testa cylindracea, frontis cirris binis pendulis, setaque caudali unica. Capsular brachionus, in a cylindric shell, with two long pendulous locks of hair proceeding from the front; the tail consists of a single bristle.

373. BRACHIONUS QUADRATUS. B. capsularis, testa quadrangula, apice bidentata, basi bicorni, cauda nulla. Capsular brachionus, in a quadrangular shell, with two small teeth at the apex, two horns proceeding from the base, and no tail.

374. BRACHIONUS IMPRESSUS. B. capsularis, testa quadrangula, apice integra, basi obtusi emarginata, cauda flexuosa. Capsular brachionus, the shell quadrangular, a smooth undivided apex; obtuse base; notched margin, and a flexuous tail.