Chapter VI: Cyclidium

Vermis inconspicuus, simplicissimus, pellucidus, complanatus, orbicularis vel ovatus. A simple, invisible, flat, pellucid, orbicular or oval worm.

83. CYCLIDIUM BULLA. C. orbiculare hyalinum. Orbicular bright cyclidium.

A very pellucid white animalculum, or orbicular skin, the edges a little darker than the rest. By the assistance of the compound microscope, some globular intestines of a very crystalline appearance are just perceptible. Its motion is slow and semicircular. It is found occasionally in an infusion of hay.

84. CYCLIDIUM MILIUM. C. ellipticum crystallinum. Elliptic and crystalline cyclidium.

It is very pellucid, of a crystalline splendour, membranaceous and elliptical; a line may be perceived through the whole length of it, a point in the fore-part, the hinder-part getting darker. Its motion is swift, fluttering, and interrupted; probably both extremities are ciliated.

85. CYCLIDIUM FLUITANS. C. ovale crystallinum. Oval crystalline cyclidium.

This is one of the smallest animalcula. The body of an oval, or rather suborbicular shape, depressed, crystalline; two small blue spaces may be discovered by the assistance of the microscope at the sides of this little creature.

86. CYCLIDIUM GLAUCOMA. C. ovatum, interaneis ægre conspicuis. Oval cyclidium, the intestines perceived with difficulty.

A pellucid oval body, with both ends plain, or an oval membrane, with a distinct well-defined edge; the intestines are so transparent that they can scarce be discerned, when it is empty; when full, they are of a green colour, and there are dark globules discoverable in the middle.

In plenty of water it moves swiftly in a circular and diagonal direction; whenever it moves slowly it seems to be taking in water, the intestines are then also in a violent commotion. Two of the smaller ones may often be perceived cohering to each other, and drawing one another by turns; nor are they separated by death, for they remain united even when the water is evaporated. Those who are not familiar with these kinds of observations, may easily mistake the shade in a single one for a junction of two, or the junction of two for a copulation, for they generate by division.

87. CYCLIDIUM NIGRICANS. C. oblongiusculum, margine nigricans. Oblong cyclidium, with a black margin.

It is very small, pellucid, and flat. With a small magnifier, it may be mistaken for an enchelis.

88. CYCLIDIUM ROSTRATIUM. C. ovale, antice mucronatum. An oval cyclidium, the fore-part pointed.

This is an oval, smooth, and very pellucid animalculum, with the fore-part running out into an obtuse point; with this it seems to feel and examine the bodies which it approaches. It is probably ciliated, though the hairs have not been discovered.

The intestines are filled with a blue liquor, forming in a tube, which, from the aperture to the middle of the body, is divided into two legs or branches; beyond the middle there are two little transverse blue lines. This colour sometimes vanishes, and then they seem to be composed of vesicles.

89. CYCLIDIUM NUCLEUS. C. ovale, postice acuminatum. An oval cyclidium, the hind-part pointed.

The body is pellucid, depressed, the fore-part obtusely convex, the hind-part acute, the intestines vesicular, the fore and hind-part on each side dark. It resembles a grape-seed.

90. CYCLIDIUM HYALINUM. C. ovatum, postice acutum. Oval cyclidium, the hind-part acute.

This cyclidium is oval, flat, and bright, without any visible intestines, the hinder-part somewhat smaller than the fore-part; it has a tremulous kind of motion.

91. CYCLIDIUM PEDICULUS. C. ovale convexum, subtus planum. An oval convex cyclidium, the bottom even. Trembley Polyp. 1, p. 282.

This is a gelatinous white animalculum, the bottom gibbous over the back, the extremities depressed and truncated, with one end sometimes apparently cloven into two; perhaps this is the aperture of the mouth. It is scarce ever seen but on the arms and the body of the hydra pallida, upon which it runs as if it had feet.

92. CYCLIDIUM DUBIUM. C. ovale, supra convexum, subtus cavum. Oval cyclidium, the upper part convex, the under part concave.

This is one of the larger species, the margin is pellucid, and the inner part contains a great number of black molecules.