Popular Science Monthly/Volume 35/June 1889/The Animal World of Well-Waters
|THE ANIMAL WORLD OF WELL-WATERS.|
"WHAT! can it be that, in the well from which we obtain our drinking-water, there are animals?" This question will undoubtedly suggest itself to one or more of my readers on seeing the heading I have given to these lines. Some of them perhaps may, in view of the existence of a "well-fauna," take a solemn pledge of total abstinence so far as the drinking of water is concerned, and hereafter quench their thirst in something else. Others may perhaps, seemingly in jest, and yet withal in truth, seriously enough ascribe a catarrh of the stomach, contracted by drinking water that was too cold, not to their own carelessness, but to some little animal which they fancy they have swallowed. Others still will play the part of skeptics, and perchance, holding a glass of water from their well up to the light, peer critically into it and exclaim: "The story is merely another fable of the scientists; we shall not believe in the existence of these creatures until we see them."
Nor can any one be blamed for taking this view of the matter. However, right here, the fact should be mentioned that it is not the clear upper portion of the well-water that contains the animal organisms, but that they occur in the lower strata, close to the bottom of the well and in the mud there. It is especially this mud that must be regarded as the native soil of the different organisms which are to be referred to in the following article; and this at once forcibly calls to our attention the fact that turbid well-water (that is, water which may be suspected of holding mud-particles in suspension) should under no circumstances be used for drinking purposes. Water, clear and sparkling, from a mountain brook, or water drawn from a good well, will, even under a microscope, present nothing that could arouse the aversion of the drinker, or raise doubts as to its desirability from a sanitary point of view.
It is but of late that the attention of naturalists, and especially of zoölogists, has been drawn to the peculiar kinds of animal life which exist in the depths of wells. Credit is due chiefly to Prof. Franz Vejdovsky, in Prague, for calling the attention of scientists to this realm of the animal world. Already many years ago the searching eye of Science had penetrated to the greatest depths of the oceans and inland seas; untiring zeal had discovered interesting phases of animal and plant life in dark caves and grottoes, as well as on the snow-fields of the Alps. But the wells had thus far been left unsearched, and here there still remained a wide field for the explorer, for the making of interesting observations and discoveries.
A peculiar circumstance led to a systematic examination of wells in search for the organisms they might contain. The death rate at Prague had grown to be very high, and this created in the mind of the public the idea that the condition of the water supply there was at fault. In 1879 a committee was appointed which was to make a practical investigation into this matter. At the request of this committee, Prof. Vejdovsky has, in a period extending over two years, examined with the microscope the water of more than two hundred wells of the city of Prague, in order to study the noxious organisms suspected of existing therein.
Of course, it is only possible to acquire knowledge of this kind by obtaining a sufficient quantity of mud from the well which is to be examined. This is done by sinking an apparatus especially constructed for the purpose into the well-shaft. The scoop consists of a stirrup made of iron, a foot and a half long and half a foot broad, to which a bag of coarse canvas is attached. This contrivance is fastened to a rope from twenty to thirty metres in length, and, in order that it should sink deep into the mud, a cannon-ball, weighing from eight to ten pounds, is fastened to it at the proper place.
According to the kind of well, the canvas bag is either dragged over the bottom, so that it may gather up the mud, or the rope is jerked up and down; the water is thus stirred up and rendered turbid, so that in this manner the mud will be caught in the bag on drawing it up to the surface.
In order to make the investigation a thorough one, a small portion of this muddy matter, which generally consists of decaying organic substances, is placed at once under the microscope, and the organisms contained in it are determined. Besides doing this, it is desirable to put a large quantity of the mud, say about one hundred grammes, into a glass jar, which can be closed, and to add some water from the well from which the mud was taken. Then this should be quietly set aside for two or three weeks, in some light spot, where the warm sunbeams can penetrate, so that any eggs or germs present in the water may be destroyed. In this way a great deal may yet be ascertained that could not have been learned at the examination conducted immediately after obtaining the sample.
"But what does the mud from such a well contain?" will be asked by the reader with whom the question what it is that he must guard against is of prime importance. This question is here to be answered. First of all, let a glance be cast at the woodcuts subjoined. Excepting Figs. 6, 7, and 8, the organisms represented are visible only under the microscope, or at least require, in order to be distinguishable, the aid of a powerful Fig. 1. magnifying lens. Nearly every particle of well-mud contains the amœbæ pictured in Fig. 1. They resemble drops of flowing liquid, and constantly change their form by sending out ray-like extensions. These extensions of the body are called pseudopodia, because their appearance creates the impression that the little animal is possessed of feet. But this is not the case; the pseudopodia (ps) are formed only in the moment when a change in location is desired, and they cease to exist when the place is reached which the little animal sought to attain. It can easily be proved that these amœbæ are animals, for they take up solid particles of food, digest the same, and cast out again whatever has not been assimilated. There is no vegetable organism which takes up solid particles into its interior for sustenance. The propagation of the amœba takes place in the simplest manner imaginable, by fission: a large specimen contracts at the center and ultimately divides into two parts, so that the mother-animal is actually rent into halves. In the body-substance of these beings, which are on the lowest plane of organic life, the microscope discloses a number of small particles, and a larger kernel (k), which is called the nucleus. Besides this there are yet one or more clear spaces called "vacuoles" (v). When fission takes place, the nucleus is also divided, and each of the newly formed organisms receives its share. These little beings are particularly entitled to our attention, because each higher organism is also originally evolved from a naked egg-cell, and devoid of any membrane or cuticle. Moreover, such a cell shows essentially the same simple structure, and moves about in the same manner as the amœba—that is, by the aid of pseudopodia.
Hence the amœbæ are one of the lowest forms of organisms known; they have remained on the lowest plane of development, and, if one accepts, with Lamarck and Darwin, the evolution of the animal world from a simplest beginning, these creatures must be regarded as the original progenitors of all forms of animal life. Of course, every one is at liberty to doubt such progressive Fig. 2. evolution of organized beings; but this much is certain, the individual development of each proceeds from a primary state, which is not greatly different from the structure of these amœbæ.
Fig. 2 represents a shell-bearing amoeba (Euglypha), which is also to be found in great numbers in the mud of wells. In this organism the naked sarcode, which consists of a substance similar to albumen, is covered and protected by a membranous envelope, or "carapace," from which, through an opening, the pseudopodia (ps) appear. The little organism pictured in Fig. 3 stands in close relationship to the preceding (Centropyxis aculeata.) Its shell, made up of diatoms and fragments of small particles of stone, shows thorn-like protuberances.
|Fig. 3.||Fig. 4.|
Fig. 4 makes us acquainted with the appearance of the flagellate infusoria. These are animals that have a delicate body, which can be contracted, and at one end of which there is a filament (gf) which is constantly in motion, and with which certain movements are executed. This filament is in reality nothing else than a long pseudopodium, which has grown to be permanent, and which has a certain function to exercise, namely, to make motions of rowing and feeling.
|Fig. 5.||Fig. 6.|
Starting with the amœba, the flagellate infusoria represent the next higher phase of morphological differentiation—that is to say, they represent the division of the homogeneous substance of the amœba into distinct parts, to which different functions are assigned. In social science one would allude to this as the commencement of a division of labor.
Fig. 5 represents an individual belonging to the genus Cothurnia, which is very frequently found in the depths of town and country wells. It possesses the power to withdraw with lightning Fig. 7. speed into the transparent envelope which surrounds it whenever the cilia which are attached to its front come in contact with anything hard. K denotes the nucleus which no infusoria lack, and v represents the vacuole, which, however, at times may disappear.
Fig. 6 pictures a small creature, the Stenostonia leucops, which attains a length of about one millimetre, and which appears to the naked eye like a minute white thread. This kind of worm is of frequent occurrence, and has received its name from the rotary motion which the cilia that are on the surface of its body impart to the water when the animal moves or swims: g g, is the nerve-center (brain-ganglion), which is very considerable in proportion to the size of the worm. The mouth is not shown in the picture, but p h is the throat, and this is followed by the sac-like "stomach-intestine" d. These worms propagate likewise by simple fission, after a new brain-ganglion has been formed at th s t, by the thickening of the two sides. A new mouth is formed by a drawing in of the outer skin. On either side of the head there is a little indentation in which longer hairs are growing. These are probably organs of sense; however, their function has not yet been determined.
Figs. 7 and 8 show a pair of crab-like animals, which are among the regular inhabitants of wells. Fig. 7 is a cyclops; Fig. 8 represents a crustacean, the Cypris. The latter is rather a peculiar object, as the animal is inclosed in a shell-like structure, called a carapace, from which only a pair of caudal appendages Fig. 8 protrude, which are provided with bristles and serve for the purpose of locomotion; oc is the eye.
A considerable number of species of cyclops are to be found in the mud of wells. Fig. 7 shows the Cyclops nanus. This little animal travels rapidly through the water by means of its swimming apparatus, to which the powerful muscles (m) lend considerable assistance. The female carries two ovisacs (ei) with numerous eggs; oc, at the front part of the body, is the eye, which is of a reddish or brown color and possesses a fine lens.
In this article we have enumerated and pictured only the principal representatives of this fauna of the wells, so that a general idea might be gained of the appearance of the animals which live in the turbid water of wells. However, to show how rich in numbers this little animal world is, the fact should be mentioned that Prof. Vejdovsky, after his careful examination of the water of two hundred and thirty-one wells of Prague, was able to announce the existence of—(1) twenty varieties of amœba-like organisms; (2) twelve varieties of flagellate infusoria; (3) forty-five varieties of other infusoria; (4) twenty-four varieties of worms; (5) ten varieties of Crustacea—making altogether a total of one hundred and eleven species of organisms. Most of these varieties were found in wells which had been polluted by the infiltration of urine and decaying organic matter. The organisms carried down by the surface water into these lower regions had found abundant food there, and were thus enabled to continue their existence. With regard to the question as to whether the water from wells that show an abundance of these forms of life is dangerous to health or not, it may be said that the danger of partaking of such water is due, not so much to the presence of the minute infusoria, worms, and Crustacea, as to the occurrence of putrefying organic matter which has found its way into these wells and there greatly favors the development of fungi. The intelligent reader will not, therefore, allow the existence of a well-fauna to interfere with his enjoyment in quaffing a cooling draught fresh from the pump; for, as already remarked, the organisms spoken of live only in the lower depths, and as a rule never reach the upper strata of the water.
Should, however, by any accident this normal state of affairs be changed, the turbid appearance of the water would indicate it, and bear at once warning to rather choose water from some other source until the well shall have resumed its normal condition, or shall have been subjected to a thorough cleaning.—Translated from Ueber Land und Meer for the Popular Science Monthly.
- Authorities differ on the question as to whether the amœbæ are covered with a membrane or not.—Translator.