CHAPTER I.

STARS OF THE SEA.

Among the many revelations of modern science, none have a more absorbing interest than those relating to the illumination of the deep sea. Until within a few years the ocean has been a sealed book. The surface forms only were known; and it was assumed that, owing to the enormous pressure, lack of sunlight, and consequent darkness, Nature, at least in the abyssal depths, was at fault, and this vast region was devoid of life and incapable of supporting it.

Recent investigations, however, have shown the reverse, and that this great area, with its plateaux, its mountain ranges, and its isolated, coral-capped peaks, whose valleys are now known to lie miles in ocean depths, teems with living forms, and, far from being the dismal realm we had supposed, is a region of surpassing wonder; which we may, _in fancy_, term that lower firmament, where float sparkling, gleaming constellations, meteor-like disks and globes with trailing luminosity, single stars and _nebulæ_ of living lights.

The phosphorescence of the sea is no new discovery, and those who have visited the seashore at night must have witnessed this phenomenon. The region of coves and beaches along the shores of Eastern Massachusetts, around Nahant particularly, is a favorable one for its full display. As the waves come rolling in upon the rocks, or upon the long, expansive shingle, in tidal measure, we see the foaming crest, seemingly igniting all along the line, more and more intense in brilliancy, when, with a roar, it breaks, masses of scintillating liquid upon the sands. We glide over the smooth portions of this sea, our boat leaving a golden train; and every dip of oar, or the dash of some affrighted fish, creates an equally vivid display. Even when not disturbed, looking down into the calm, clear depths, the same phenomenon is witnessed. Pale, ghostly forms are seen here and there, moving slowly about, while the seeming silvery atoms suggest the _nebulæ_ of this submarine sky. Deeper yet, the bottom shows weird splendors. The great kelps are bedecked with mystic lights, and gleam like diamond’s flash from ledge and rock.

These wonderful exhibitions of submarine illumination are due to the presence of luminous creatures, or in some cases to large animals swimming through immense numbers of small phosphorescent bodies, so appearing as light-givers themselves.

In nearly every branch of the animal kingdom we shall find these _living lights_; some marvellously brilliant, others glowing with dim rays, and all contributing often to wondrous illumination, far-reaching or circumscribed.

[Illustration:

PLATE I.

LUMINOUS PROTOZOANS.

_Noctilucæ_ (in milk).

_Noctiluca miliaris_ (magnified 100 diameters).

_N. miliaris_ (slightly magnified).

LUMINOUS PORTION OF NOCTILUCA

(highly magnified).]

If the ocean which contains these wondrous forms should suddenly become dry, we should find that its contour is very similar to that of the land. There would be hills, valleys, plains, mountains, and seeming river-beds where currents have flowed; and so sharply are these defined, where growing atolls and reefs abound, one may stand--as I have often done upon those of the Florida reef--and drop a leaded line almost directly to the bottom in the clear blue waters.

This submarine scenery would not show the rough and jagged outlines which are a characteristic of terrestrial mountain ranges. Nearly all prominences in water at a considerable depth are well rounded off by a coating of fine ooze, formed of the minute and delicate shells of the _globerigina_, one of the lowest organized of animal life. These little creatures live upon the bottom, or in the watery space above, and the ooze which makes the sea-bottom, in great thickness, is almost entirely made up of the dead and cast-off shells of these microscopical creatures. The chalk cliff of Dover, England,--that white headland which has given the ancient name of Albion to the mother country,--is an upheaved mass of the same material, once found in the ocean bottom, now elevated by some geological change, and hardened into chalk, which it really is. What a surprising monument, erected by Nature’s processes from the myriads of bodies of her most minute and most simply organized animals!

The familiar modern term “protoplasm” represents what is know to be the simplest form of life; scarcely more, seemingly, than a bit of jelly, without form, and we might say void of organization, for it is alive, and yet has no nerves, no organized vessels which we can perceive, but exists in our pools as the least organized animal known.

There is a species which belongs to one of the numerous kinds or groups of this the first and least perfect of the animal kingdom, which has also the great distinction of being the best known and most brilliant of marine light-bearers. This is the _Noctiluca_, or, as its name implies, the night-light. This little creature, but little more than visible to the naked eye, is the largest of the so-called infusorians; others of this group of animals requiring the aid of a microscope to determine the form. It is but little more in structure than the bit of protoplasm, or simplest organism or animal known. It looks when magnified--its natural size being about that of a pin’s head--much more highly organized than the others, by being almost a complete globe, and provided with a whip-like process or member. It is also veined somewhat, and reminds one of a currant or gooseberry. Now, it is often noticed that the smaller the animal, the more numerous; indeed, also, the more numerous its progeny. We may well be prepared, then, to hear that these minute creatures often swarm on the ocean surface in myriad masses.

Fig. 1. of Plate I. represents the _Noctiluca_ magnified one hundred times. Fig. 2. of the same, represents the appearance of the creature when luminous, and only slightly magnified. The long lash which extends from the side is the locomotive organ. It is attached to the body near what is supposed to be the mouth; though these creatures are so simple that many kinds, just below in organization, have no definite mouth nor stomach, but absorb food from any surface of the body which comes in contact with it.

This infusorian and most potent of living lights, albeit of extreme minuteness and simplicity as an organism, is abundant in the ocean along the European shores, and is often seen in our north-eastern waters, notably off Portland harbor and along shore to Cape Ann. I have enjoyed the privilege of witnessing the fullest glory of this little creature’s effulgence. In our so-styled ocean firmament these living asteroids shine forth in those waters, and rival, if not excel, in light-giving any other known creature.

In the endeavor to study the mysterious lights, I spent considerable time on a rocky point which jutted out into the sea, at Ogunquit, Me., with my microscope at hand, as near as possible to the water; thus examining them while comparatively fresh from the sea. In taking up the little creatures, they assume a pear shape, from contraction,--the only evidence, seemingly, of life, but blazing with a flashing light over their entire surface. We had the advantage of having specimens fresh at hand, yet there are certain appliances indispensable for such work which we did not have, and, therefore, could not then perfect our dissections sufficiently to get satisfactory results. We must refer the reader, therefore, to the experiments detailed in the Appendix.[1]

In watching the light of the _Noctiluca_, we are reminded of the flash-light of a light-house,--the gleam appearing and disappearing with considerable regularity. It is difficult to trace the light to any particular portion of the body. In Plate I., Fig. III., is shown the supposed luminous organs, which would seem to show that there are luminous spots. Sometimes the light seems to pervade the entire body; again, to be in the outer skin or cuticle. When the light appears after an intermission, the spots referred to become luminous first, the light extending to the outer surface.

The conditions most favorable for respiration produce the greatest exhibitions of light; thus, if the water is constantly aërated, or disturbed so that the air has access, the gleam is intensified. If the animal is touched with the point of a needle, the light is quickly visible; and just before death it is continuously luminous, the phosphorescence disappearing just after dissolution. Experiments have shown that in a vacuum the light diminishes,--carbonic gas producing the same result. Humboldt refers to his luminous appearance after bathing in water abounding in _Noctilucæ_; and among the curious experiments might be mentioned one where print was read by a gobletful of these little creatures which rendered them living lamps, literally.

M. de Tessan, a French observer, has recorded a phenomenon, which, I should judge, was due to _Noctilucæ_, with perhaps the additional light of other forms. The accompanying picture on plate II. was made from his description, showing the light, and people upon the shore endeavoring to read by it. He writes: “On the 10th of April, in the evening, the sea in the roadstead of Simonstown, Cape of Good Hope, presented an extraordinary phosphorescence of a most vivid character. At whatever points the phosphorescence was greatest, the water was colored on the surface as red as blood; and it contained such an immense quantity of little globules that it had the consistency of sirup. A bucket of water taken up at one of these points, and filtered through a piece of linen, left in the filter a mass of globules greater in volume than the water that had passed through; in other words, the globules constituted more than half of the whole quantity of sea water taken up in the bucket. Viewed under the magnifying-glass, these globules presented the appearance of little transparent and inflated bladders, having on their surface a black point surrounded with equally black radiating _striæ_.... The least agitation or slightest contact made them throw out a vivid greenish light.”

[Illustration:

PLATE II.

M. DE TESSAN READING BY LIGHT OF PHOSPHORESCENT SEA.]

As the waves washed in, M. de Tessan describes the light as appearing like the vivid flashes of lightning. “It lighted up the chamber that I and my companions occupied in the house of Mr. Ball, though it was situated more than fifty yards distant from the breakers. I even attempted to write by the light, but the flashes were of too short duration.”

When a vessel is ploughing through masses of these animals, the effect is extremely brilliant. An American captain states that when his ship traversed a zone of these animals in the Indian Ocean, nearly thirty miles in extent, the light emitted by these myriads of fire-bodies, of which he estimated there were thirty thousand in a cubic foot of water, eclipsed the brightest stars; the milky way was but dimly seen; and as far as the eye could reach the water presented the appearance of a vast, gleaming sea of molten metal, of purest white. The sails, masts, and rigging cast weird shadows all about; flames sprang from the bow as the ship surged along, and great waves of living light spread out ahead,--a fascinating and appalling sight.

The enormous quantity of _Noctilucæ_ in the water explains the intensity of the light. In experiments made at Bologne, one-seventh to one-half of a given amount of water taken up consisted of these minute light-givers, and Rymer Jones found thirty thousand in a cubic foot. According to Quatrefages, the light of _Noctilucæ_ in full vigor is a clear blue; but, if the water is agitated, it becomes nearly, if not quite white, producing rich silvery gleams sprinkled with greenish and bluish spangles.

Regarding the intensity of the light, a tube fifteen millimetres in diameter, containing a bed of _Noctilucæ_ at the surface twenty millimetres thick, emitted light sufficient to see the face of a watch and read the figures; and, if the little creatures were agitated, time could be ascertained at a distance of a foot. M. Quatrefages found that the most delicate thermometer was not affected by the light; and he assumes that it is not combustion from the fact that oxygen gas, when introduced, does not restore the light after it has disappeared at the death of the animal. His conclusion is, that the light is produced by the contracting of the interior mass of the body; and that the flashes, or scintillations, are due to the rupture and rapid contraction of the filaments of the interior. The fixed light he explains as resulting from the permanent contraction of the contractile tissues adhering to the inner surfaces of the general envelope. Giglioli is especially enthusiastic over the light of the _Noctilucæ_ and other forms; and to show its general distribution he says that in fifty-five thousand marine miles traversed by the “Magenta,” the Italian exploring-ship, in four hundred and thirty-nine days, phosphorescence was observed more than half of the time. He met _Noctilucæ_ in the Bay of Naples, at Rio, in the Straits of Banca, while in the east coast of Asia; and at Port Jackson “the same milky uniform light was seen, without any green or bluish tint,” and again at Valparaiso. He observed, including _Noctiluca miliaris_, three luminous forms, all differing in the color of their light. The one observed on the Asiatic coast emitted a green light, and is called by M. Giglioli, _N. homogenea_. The Pacific form, _N. pacifica_, has a whitish luminosity, and differs from the others materially in form and structure.

In many of the ports of tropical and semi-tropical America, it is the custom to bathe in the ocean at night, the warmth of the water rendering such recreation enjoyable. A gentleman newly arrived at one of the places on the Pacific coast proceeded at night to take a bath, and, upon rising from the water, was astonished and amazed to find that his entire body was luminous, seeming covered with a coating of light, which he found originated from innumerable minute phosphorescent animals, which clung to his garments, and changed the water all about to a golden hue.

A distinguished professor at Keil was, perhaps, the first to discover luminous microscopic animals.[2]

The largest of these minute creatures is about one-eighth of a line, the smallest from a forty-eighth to a ninety-sixth of a line in size.

Giglioli has made some interesting observations regarding the phosphorescence of the lowest class of animal life, the protozoans, and with his colleague, Professor de Fillipi, intends publishing the results of their observations.[3]