PREFACE.
The object of the present work is to interest young people in natural history by the presentation of an attractive—indeed, marvellous—phase of nature, and to encourage healthful outdoor observation, as well as habits of investigation.
The subject chosen for this work—that embracing the phenomenon of luminosity in animals, plants, and inorganic matter, and especially those that seem intended as illuminators of the ocean—is one which has ever possessed a fascination for the author.
During many years spent on Southern shores, in constant association with the most attractive features of marine life, the remembrance of the splendors of the night festivals of these wondrous ocean forms is most enduring. No fairy tale of human invention can relate to us more fascinating scenes than are realized in Nature’s carnivals of the sea. Not only is the surface of the ocean, when lashed into foam by the tempest, luminous, but the greater depths, where the water is cold, near the freezing-point, and subject to pressure so great that instruments of glass are shattered and reduced to powder, abound in living lights.
And this abyssal region, covered by miles in depth of water, and which was formerly considered to be the most desolate region upon the globe, is inhabited by light-givers of marvellous beauty and brilliancy.
The little Malacosteus, with its gleams of yellow and green; Stomias, with sparkling side-lights; the dazzling effulgence of Pyrosoma; the comet-like glare of Medusæ, with their tints of many colors,—present a series of wonders which must excite the admiration of the most indifferent observer.
In the United States, there are ten thousand enrolled young naturalists, comprising the Agassiz Association. As one of a committee solicited to answer questions propounded by the young people, members of this association and of the Chautauqua Circle, I have often been surprised at the nature of the queries, which shows that this army of young observers includes many who are not merely collectors of curiosities, but are naturalists in the best sense. They are systematic inquirers, and working in the right direction to become scientists, should they continue.
It is to these young scientists, their unscientific elders, and the boys and girls in general who have not yet had their interest aroused in Nature’s works, that this volume is addressed; and if some information is conveyed, while appearing merely to entertain, one object of the author will have been accomplished.
The subject of phosphorescence is one which affords the widest field for investigators; as, while the most careful descriptions of the light-emitting organs have been made, the actual cause of animal phosphorescence is unknown. Material for study is ever at hand; the fire-fly courts attention at every summer door-yard, and the pools of beach and cove are illumined by ocean forms. Even the simplest experiments are of the greatest interest. I have read by the light of a luminous beetle, and have determined the time of night while holding my watch in the glare of ocean animals. Von Bibra wrote his description of the Pyrosoma by its own light; the shark of Bennett illuminated his cabin like a chandelier; photographs have been taken by the light of luminous beetles and by phosphorescent plates; and probably the day is not distant when more important uses will be found for this wonderful light, which, in default of a better name, we term phosphorescence. It is found in the animal, vegetable, and the mineral kingdoms; in life and in death; in growth and in decay. It illumines, but does not appear to consume, and without perceptible heat exists where ordinary combustion is impossible.
From the nature of the subject, it is evident that illustrations of the phosphorescence of marine animals must be more or less conjectural; and those given, representing over fifty luminous forms, show as nearly as possible the probable effect produced. As this work is scientific only so far as to secure accuracy, some technical details have been omitted. To compensate in a measure, I have appended a fairly complete bibliography of most important monographs and papers on the subject, which may be of value to those who wish to pursue the subject in its technical relations.
To render the work as popular as possible, certain systematic portions necessary to the student are placed in an appendix, and referred to by number. The whole work is also thoroughly indexed.
While the chief feature of the volume embraces the phosphorescence of animals, it has been deemed advisable to include reference to luminous plants, minerals, and certain atmospheric phenomena, which, if not strictly comprehended under our title, will perhaps not be considered entirely foreign nor uninteresting in this connection.
It is my agreeable duty to acknowledge here the courtesy and kindly attentions received from M. Raphaël Dubois of the Zoölogical Society of France; Professor H. Filhol; Professor H. H. Giglioli, Director of the Zoölogical Institute of Florence, Italy; Professor Carlo Emery of the University of Bologna, Italy; and M. Zenger of Prague, Hungary, who generously forwarded for my use their most recent papers on the subject of phosphorescence.
I have also to name with thanks for similar favors Dr. Gunther, keeper of the British Museum, and acknowledge the value of contributions from the works of M. Quatrefages of the Institute of France.
C. F. H.
Pasadena, Cal., July, 1887.