And here I may mention the evident use of these wonderful beings. They appear wherever decaying animal or vegetable substances are found in water, and are extremely useful in destroying what would otherwise taint the air with noxious gasses and smells. Minute algæ also assist in preserving the purity of the water in which they live; they serve as food, also, to animals higher in the scale of creation than themselves. Captain Sir James Ross, in his Antarctic Voyage, speaking of a small fish found by him in the South Seas, and stating by what means it and many others are fed, says, "All are eventually nourished and sustained by the minute infusorial animalcules, which we find filling the ocean with an inconceivable multitude of the minutest forms of organic life." We may infer from this, the immense importance of the Infusoria in the scale of existence, for although only remotely supporting the higher animals, yet the want of them would be greatly felt. Ehrenberg states, that a single drop of water may hold five hundred millions of the smallest animalcules. What, then, can be the population of a lake or of the ocean?
I have watched specimens of the genera Floscularia, Vorticella, and Stentor, for hours at a time, and they have never ceased to feed on minute portions of animal and vegetable substances, brought to them by the current they are enabled to make in the water; others eagerly pursue their prey, or feed on the decaying vegetable matter floating about: indeed, the appetite of these little creatures seems insatiable. Many genera have a strong chewing apparatus, like a mouth armed with teeth. All seem employed in the same way, though using different methods. Much decaying matter must thus be taken away by this insatiable, though miniature army, provided for the purpose. They, in their turn, afford sustenance to aquatic insects, which are again preyed on by fishes; and thus food is prepared for more highly organized animals, and lastly for man.
Animalcules have never been observed to rest, or at least to sleep; but this may be partly owing to the light necessarily used in viewing them, which forms an artificial sunlight, exciting their powers of motion: they may rest during darkness, when they can not be seen by us. Many are only attracted to the surface of the water by the light of the sun, and are difficult to be obtained on a dull day; they are, however, not much affected by cold or heat, for they are procurable in winter as in summer, though not in such profusion: they are found even under thick ice, and I have frequently broken, in severe frost, the frozen surface of a pond, and, inserting a bottle, have obtained some most interesting kinds. Many of the Polygastrica will bear a great degree of cold, even more so than those of the class Rotatoria, whose organization is of a higher order.
It has, I believe, been generally observed, that the more simple the organization of animals, the more retentive is the creature of life, and this is the case with these minute beings. The Rotifer vulgaris will even bear revivification several times. Dr. Carpenter relates that he tried the experiment six times with twelve specimens, and each time some were perfectly restored to animation. By allowing the drop of water which held them to evaporate, and at the end of twenty-four hours giving them a fresh supply, he succeeded six times in restoring some of them: at last two only were left, and these unfortunately he lost. Ehrenberg affirms, that if thoroughly desiccated they can not revive, but that they may remain in a lethargic condition if deprived of water for a certain time only. The same naturalist observes that when an animalcule is frozen with the water, it is surrounded by an exceedingly small portion which is unfrozen, occasioned probably by the animal heat of its body; but, should the cold be so great as to freeze this, the creature dies. Animal heat in such an atom! how marvelous! Yet they will bear a great degree of heat also. The same naturalist says, that the Polygastrica, will bear the temperature gradually raised to 120° of Fahrenheit, and some even to 200°, but if raised suddenly they die at 140°. Now, if we consider that water raised to 212° is boiling, we shall be as much astonished at their powers of enduring heat as cold. Sir James Ross, in his Antarctic Expedition, found upward of seventy species of Polygastrica with loricæ, or silicious shells, in fragments of ice.
It will, therefore, be seen, that animalcules are obtainable at all seasons, and in every place where there are ponds or pools of water; or they may be procured from water-butts, or by placing leaves, hay, or almost any vegetable substance in a little water, which has been previously found to have nothing living in it.
[EDWARD DRYSDALE.]
A LEAF FROM THE DIARY OF A LAW-CLERK.
About the year 1798, James Bradshaw and William Drysdale, both invalided masters of the Royal Navy, cast anchor for the remainder of their lives at about twelve miles' distance from Exeter, on the London road. Bradshaw named his domicile, an old-fashioned straggling building, "Rodney Place," in honor of the Admiral in whose great victory he had fought. Drysdale's smaller and snugger dwelling, about half a mile away from "Rodney Place," was called "Poplar Cottage," and about midway between them stood the "Hunter's Inn," a road-side public-house, kept by one Thomas Burnham, a stout-hearted, jolly-bellied individual, the comeliness of whose rubicund figure-head was considerably damaged by the loss of an eye, of which, however, it is right to say, the extinguished light appeared to have been transferred in undiminished intensity to its fiery, piercing fellow. The retired masters, who had long known each other, were intimate as brothers, notwithstanding that Bradshaw was much the richest of the two, having contrived to pick up a considerable amount of prize-money, in addition to a rather large sum inherited from his father. Neither did the difference of circumstances oppose, in Bradshaw's opinion, the slightest obstacle to the union of his niece and heiress, Rachel Elford, with Edward Drysdale, his fellow-veteran's only surviving offspring. The precedent condition, however, was, that Edward should attain permanent rank in the Royal Navy, and with this view, a midshipman's warrant was obtained in '99 for the young man, then in his eighteenth year, and he was dispatched to sea.
The naval profession proved to be, unfortunately, one for which Edward Drysdale was altogether unfitted by temperament and bent of mind, and sad consequences followed. He had been at sea about eighteen months, when news reached England of a desperate, but successful cutting-out affair by the boats of the frigate to which he belonged. His name was not mentioned in the official report—but that could hardly have been hoped for—neither was it in the list of killed and wounded. A map of the coast where the fight took place was procured; the battle was fought over and over again by the two veterans, and they were still indulging in those pleasures of the imagination in the parlor of the "Hunter's Inn," when the landlord entered with a Plymouth paper in his hand, upon one paragraph in which his single orb of vision glared with fiery indignation. It was an extract from a letter written by one of the frigate's officers, plainly intimating that midshipman Drysdale had shown the white feather in the late brush with the enemy, and would be sent home by the first opportunity. The stroke of a dagger could have been nothing compared with the sharp agony which such an announcement inflicted on the young man's father, and Bradshaw was for a few moments equally thunder-stricken. But he quickly rallied. William Drysdale's son a coward! Pooh! The thing was out of nature—impossible; and very hearty were his maledictions, savagely echoed by Burnham, with whom young Drysdale was a great favorite, of the lying lubber that wrote the letter, and the newspaper rascals that printed it.