An object like this should be watched at intervals for hours and even days, especially if the eggs are nearly ready to give up their infantile contents. This was the case with the specimen described, and after a few hours a young Floscule escaped, looking very much like a clumsy little grub. After a few awkward wriggles the new-born baby became more quiet, and on looking at it again at the expiration of seventeen hours, it had developed into the shape of a miniature plum-pudding, with five or six tiny lobes expanding their tufts of slender hair. Unfortunately its further proceedings were not seen, or it would have been interesting to note the growth of the foot, and the formation of the gelatinous tube, which is probably thrown off in rings.
To view the details of the structure of a Floscule, it must be placed in a live-box or compressorium, and if specimens are scarce, they should not be allowed to remain in the limited quantity of water those contrivances hold, after the observations are concluded, but should be carefully removed, and placed in a little vial, such as homœopathists use for their medicine. By such means an individual may be kept alive for many days. It is also interesting to place a little branch of the plant occupied by Floscules or similar creatures, in a glass trough, where they may be made quite at home, and their proceedings agreeably watched by a one-inch or two-thirds power. These troughs,[11] which can be obtained of the optician, should be of plate glass, about three inches long, nearly the same height, and about half an inch wide. If narrower, or much taller, they will not stand, which is a great inconvenience. The pieces of glass are stuck together with marine glue, and a very simple contrivance enables the plants or other objects to be pressed near the front, and thus brought into better view. A strip of glass, rather narrower than the width of the trough, is dropped into it, and allowed to fall to the bottom. Then a piece of glass rather shorter than the trough, and rather higher than its front side, is placed so as to slope from the front of the bottom towards the back at the top. The piece of glass first dropped in keeps it in the right position, and the trough is thus made into a V-shaped vessel, wide at the top and gradually narrowing. Any object then placed in it will fall till it fits some part of the V, where it will remain for observation. A small wedge of cork enables the moveable piece of glass to be thrown forwards, until it assumes any angle, or is brought parallel to the front of the trough.
[11] The shallow cells with thin sliding covers devised by Mr. Curteis (of Baker's), are still more convenient when no pressure is required, and the objects are small. When not under the microscope they can be kept full of water by immersion in a tumbler.
A power of five or six hundred diameters generally enables a movement of small globules to be seen at the extremity of the lobes of the Floscule, and the gizzard may be made plain by dissolving the rest of the creature in a drop of solution of caustic potash. It also becomes more visible as the supply of food falls short. Mr. Gosse describes the body as "lined with a yellowish vascular membrane," and young specimens exhibit two red eyes, which may or may not be found in adults. When these eyes of Rotifers are not readily conspicuous, they must be sought for by opaque illumination, or by the dark-ground method which, especially with the parabola, is successful in bringing them out.
Naturalists, and possibly the specimens also, do not always agree in the number of lobes assigned to the "Beautiful Floscule," and although it is easy enough to count them in some positions, the observer may have to exercise a good deal of patience before he is certain whether they are five or six. For a long evening only five could be discerned in the specimen now described, but the next night six were apparent without difficulty or doubt. The hairs also will not appear anything like their true length or number, unless the object-glass is good, and great care is taken not to obscure them by a blaze of ill-directed light.
Chætonotus larus (swimming).
After the Floscules had been sufficiently admired and put aside, for observations to be repeated on future occasions, a Rotifer attracted attention by his merry-andrew pranks, throwing himself in all directions by means of two long and extremely mobile toes attached to his tail-foot. Then came a creature swimming like an otter, thrusting his head about on all sides, and looking much more intelligent than most of his compeers of the pond. Looked at vertically, he was somewhat slipper-shaped, the rounded heel forming his head, then narrowing to a waist, and expanding towards the other end, which projected in a fork. All round him were long cilia, which were conspicuous near the head, and a fine line indicated the passage from his mouth to the stomach, which seemed full of granular matter. Presently he took to crawling, or rather running, over a thread of conferva, and then his back was elegantly arched, and his cilia stood erect like the quills of a porcupine. This was the Chætonotus larus.
Chætonotus larus (crawling).