Chapter III: Volvox

Volvox inconspicuus, simplicissimus, pellucidus, sphæricus. An invisible, very simple, pellucid, spherical worm.

13. VOLVOX PUNCTUM. V. sphæricus, nigricans, puncto lucido. Spherical, of a black colour, with a lucid point.

A small globule; one hemisphere is opake and black, the other has a pellucid crystalline appearance; a vehement motion is observable in the dark part. It moves in a tremulous manner, and often passes through the drop, turning round as if upon an axis. Many may be often seen joined together in their passage through, the water; they sometimes move as in a little whirlpool, and then separate. They are found in great numbers on the surface of fetid sea water.

14. VOLVOX GRANULUM. V. sphæricus, viridis, peripheria hyalina. Spherical and green, the circumference of a bright colour.

There seems to be a kind of green opake nucleus in this animalculum; the circumference is transparent. It is to be found generally in the month of June, in marshy places; it moves but slowly.

15. VOLVOX GLOBULUS. V. globosus; postice subobscurus. Globular volvox, the hind-part somewhat obscure.

This globular animalculum is ten times larger than the monas lens; it verges sometimes a little towards the oval in its form. The intestines are just visible, and make the hinder part of the body appear opake; it has commonly a slow fluttering kind of motion, but if it be disturbed, the motion is more rapid. It is found in most infusions of vegetables.

16. VOLVOX PILULA. V. sphæricus, interaneis immobilibus virescentibus. Small round volvox, with immoveable green intestines.

This is a small transparent animalculum; its intestines are immoveable, of a green colour, and are placed near the middle of the body, the edges often yellow; a small obtuse incision may be discovered on the edge, which is, perhaps the mouth of the animalculum. This little creature appears to be encompassed with a kind of halo or circle. If this be occasioned by the vibratory motion of any fringe of hairs, they are invisible to the eye, even when assisted by the microscope. It seems to have a kind of rotatory motion, at one time slow, at another quick; and is to be found in water where the lemna minor, or least ducks-meat, grows, sometimes as late as the month of December.

17. VOLVOX GRANDINELLA. V. sphæricus, opacus, interaneis immobilibus. Spherical and opake, with immoveable intestines.

This is much smaller than the preceding, and is marked with several circular lines; no motion is to be perceived among the interior molecules. It sometimes moves about in a straight line, sometimes its course is irregular, at others it keeps in the same spot with a tremulous motion.

18. VOLVOX SOCIALIS. V. sphæricus, moleculis crystallinis, æqualibus distantibus. Spherical volvox, with crystalline molecules, placed at equal distances from one another.

When very much magnified this animalculum seems to have some relation to the vorticella socialis, as seen with the naked eye. It consists of crystalline molecules, disposed in a sphere, and filling up the whole circumference; they are all of an equal size. Whether they are included in a common membrane, or whether they are united by one common stalk, as in the vorticella socialis, has not been discovered. We are also ignorant of the exact figure of the little particles of which it is composed; when a very large magnifying power is used, some black points may be discerned in the center of the crystalline molecules. The motion is sometimes rotatory, sometimes from right to left, and the contrary. It is found where the chara vulgaris has been kept.

19. VOLVOX SPHÆRICULA. V. sphæricus, moleculis similaribus rotundis. Pl. XXV. Fig. 6. Spherical volvox, with round molecules.

This spherule is formed of pellucid homogeneous points of different sizes. It moves slowly about a quarter of a circle from right to left, and then back again from left to right.

20. VOLVOX LUNULA. V. hemisphæricus, moleculis similaribus lunatis. Plate XXV. Fig. 7. An hemispherical volvox, with lunular molecules.

Is a small roundish transparent body, composed of innumerable molecules, homogeneous, pellucid, and of the shape of the moon in its first quarter, without any common margin. It is in a continual two-fold motion; the one, of the whole mass turning slowly round; the other, of the molecules one among the other. They are found in marshy places in the beginning of spring.

21. VOLVOX GLOBATOR. V. sphæricus membranaceus. Spherical membranaceous volvox.

This is a transparent globule, of a greenish colour; the fœtus is composed of smaller greenish globules. It becomes whiter and brighter with age, moves slowly round its axis, and may be perceived by the naked eye. But to the microscope the superficies of this pellucid membrane appears covered with molecules, as if it were granulated, which has occasioned some observers to imagine it to be hairy; the round pellucid molecules that are fixed in the center are generally largest in those that are young. The exterior molecules may be wiped off, leaving the membrane naked. When the young ones are of a proper size, the membrane opens, and they pass through the fissure; after this the mother melts away. They sometimes change their spherical figure, the superficies being flattened in different places. Most authors speak of finding eight lesser globules within the larger; but Müller says, that he has counted thirty or forty of different sizes. This wonderful capsulate situation of its progeny is well known; indeed it often exhibits itself big with children and grand-children.

Leeuwenhoeck was the first who noticed this curious animalculum, and depicted it; a circumstance which has not been mentioned by Baker and other microscopic writers, who have described it. It may be found in great plenty in stagnant waters in spring and summer, and in infusions of hemp-seed and tremella. Baker describes it as follows: This singular minute water animal, seen before the microscope, appears to be exactly globular, without either head, tail, or fins. It moves in all directions, forwards or backwards, up or down, rolling over and over like a bowl, spinning horizontally like a top, or gliding along smoothly without turning itself at all. Sometimes its motions are very slow, at other times very swift; and when it pleases, it can turn round as upon an axis very nimbly, without moving out of its place. The body is transparent, except where the circular spots are placed, which are probably its young. The surface of the body in some is as it were dotted all over with little points, and in others, as if granulated like shagreen. Baker thought also that in general it appeared as if it was set round with short moveable hairs. By another writer they are thus described: These animalcula are at first very small, but grow so large as to be discerned with the naked eye; they are of a yellowish green colour, globular figure, and in substance membranaceous and transparent. In the midst of this substance several small globes may be perceived; each of these are smaller animalcula, which have also their diaphanous membrane, and contain within themselves still smaller generations, which may be distinguished by the assistance of very powerful glasses. The larger globules may be seen to escape from the parent, and then increase in size, as has been already observed.

22. VOLVOX MORUM. V. membranaceus orbicularis, centro moleculis sphæricis viridibus. Membranaceous orbicular, with spherical green molecules in the center.

This animalculum has some resemblance to the volvox uva, but is sufficiently distinguished by the surrounding bright orbicular membrane: the middle part is full of clear green globules. The globules seldom move, though a quivering motion may sometimes be perceived at the center. It has a slow rotatory motion, and is found amongst the lemna, in the months of October and December.

23. VOLVOX UVA. V. globosus, moleculis sphæricis virescentibus nudis. Globular volvox, composed of green spherical globules, which are not inclosed in a common membrane.

This animalculum seems to be a kind of medium between the volvox pilula, No. 16, and the gonium pectorale, No. 114, being, like the one, composed of green spherules, and in form, resembling the other. It consists of a congeries of equal globules of a greenish colour, with a bright spot in the middle; the whole mass is sometimes of a spherical form, sometimes oval, without any common membrane; a kind of halo may be perceived round it, but whether this is occasioned by the motion of any invisible hairs has not been discovered. The mass generally moves from right to left, and from left to right; scarce any motion can be discovered in the globules themselves. It was found in the month of August, in water where the lemna polyrrhiza was growing. Two masses of these globules have been seen joined together. They contain from four to fifty of the globules, of which a solitary one may now and then be found.

24. VOLVOX VEGETANS. V. ramulis simplicibus et dichitomis, rosula globulari terminatis. A volvox with simple dichitomous branches, terminating in a little bunch of globules.

It consists of a number of floccose opake branches, which are invisible to the naked eye; at the apex of these there is a little congeries of very minute oval pellucid corpuscles. Müller at first thought it to be a species of microscopic and river sertularia; but afterwards he found the bunches quitting the branches, and swimming about in the water with a proper spontaneous motion. Many old branches were found deserted of their globules, while the younger branches were furnished with them. It was found in river water in November 1779 and 1780.