The Nature of Animal Light.

by E. Newton Harvey.

ANNOUNCEMENT

The rapid increase of specialization makes it impossible for one author to cover satisfactorily the whole field of modern Biology. This situation, which exists in all the sciences, has induced English authors to issue series of monographs in Biochemistry, Physiology, and Physics.

A number of American biologists have decided to provide the same opportunity for the study of Experimental Biology.

Biology, which not long ago was purely descriptive and speculative, has begun to adopt the methods of the exact sciences, recognizing that for permanent progress not only experiments are required but quant.i.tative experiments. It will be the purpose of this series of monographs to emphasize and further as much as possible this development of Biology.

Experimental Biology and General Physiology are one and the same science, in method as well as content, since both aim at explaining life from the physico-chemical const.i.tution of living matter. The series of monographs on Experimental Biology will therefore include the field of traditional General Physiology.

JACQUES LOEB, T. H. MORGAN, W. J. V. OSTERHOUT.

PREFACE

Bioluminescence, the production of light by animals and plants, has always excited the admiration of the layman and the wonder of the scientist. It is not surprising that an enormous literature dealing with the subject has grown up. A large part of this literature, however, is made up merely of reports that a certain animal is luminous, or records of especially brilliant phosph.o.r.escence of the sea. Among those who have inquired somewhat more carefully into the nature and causes of light production may be mentioned the names of Beijerinck, R. Boyle, Dahlgren, Dubois, Ehrenberg, Krukenberg, Mangold, McDermott, Molisch, Panceri, Pfluger, Phipson, Quatref.a.ges, Spallanzani, and Trojan. Several of these men have written comprehensive monographs on the subject.

It is not the purpose of this book to deal with every phase of bioluminescence. Volumes could be written on the evolutionary side of the problem and the structure and uses of luminous organs. These questions can only be touched upon. Neither is it my purpose to discuss the ultimate cause of the light, whether due to vibration of electrons or to other causes. That problem must be left to the physicist, although it is highly probable that a study of animal light will give important information regarding the nature of light in general, and no theory of light can be adequate which fails to take into account the extraordinary powers of luminous animals.

We shall be concerned largely with the physical characteristics of animal light and the chemical processes underlying its production.

Great advances have been made since the first early guesses that the light was due to phosphorus and was a kind of oxidation. Although the problem cannot be considered as solved, it has been placed on a sound physico-chemical basis. Some material is oxidized. Exactly what this material is and why light accompanies its oxidation are the two more fundamental problems in the field of Bioluminescence. How far and with what success we have progressed toward a solution of these problems may be seen from a perusal of the following pages.

It gives me pleasure to acknowledge the kindness of Dr. W. E. Forsythe of the Nela Inst.i.tute, Cleveland, Ohio, in reading and criticizing the ma.n.u.script of Chapter III, and of Professor Lyman of Harvard University for a similar review of Chapter II. I am also deeply indebted to my wife for reading the proof and to Dr. Jacques Loeb and Prof. W. J. V.

Osterhout for many suggestions throughout the book. My thanks are also due to Prof. C. Ishikawa of the Agricultural College, Imperial University of Tokio, j.a.pan, for his generous a.s.sistance in providing _Cypridina_ material. Finally I wish to acknowledge the support of the Carnegie Inst.i.tution of Washington, through its director of Marine Biology, Dr. Alfred G. Mayor. Without this support much of the work described in this book could not have been accomplished.

E. N. H.

THE NATURE OF ANIMAL LIGHT

CHAPTER I

LIGHT-PRODUCING ORGANISMS

The fact that animals can produce light must have been recognized from the earliest times in countries where fireflies and glowworms abound, but it is only since the perfection of the microscope that the phosph.o.r.escence of the sea, the light of damp wood and of dead fish and flesh has been proved to be due to living organisms. Aristotle mentions the light of dead fish and flesh and both Aristotle and Pliny that of damp wood. Robert Boyle in 1667 made many experiments to show that the light from all three sources, as well as that of the glowworm, is dependent upon a plentiful supply of air and drew an interesting comparison between the light of shining wood and that of a glowing coal.

Boyle had no means of finding out the true cause of the light and early views of its nature were indeed fantastic. Even as late as 1800 Hulme concludes from his experiments on phosph.o.r.escent fish that the light is a "const.i.tuent principle of marine fishes" and the "first that escapes after the death of the fish." It was only in 1830 that Michaelis suspected the light of dead fish to be the result of some living thing and in 1854 h.e.l.ler gave the name _Sarcina noctiluca_ to the suspected organism. In 1875 Pfluger showed that nutrient media could be inoculated with small amounts of luminous fish and that these would increase in size, like bacterial colonies, and we now know that the light of all dead fish and flesh is due to luminous bacteria.

In the early part of the nineteenth century it was surmised that the light of damp wood was connected with fungus growth because of a similarity in smell. In 1854 h.e.l.ler recognized minute strands, which he called _Rhizomorpha noctiluca_, as the actual source of the light. We now know that all phosph.o.r.escent wood is due to the mycelium of various kinds of fungi and that sometimes the fruiting body of the fungus also produces light.

The phosph.o.r.escence or "burning of the sea," which is described by so many of the older explorers, is also due entirely to living organisms, both microscopic and macroscopic. The latter are mostly jelly-fish (_medusae_) or comb jellies (_Ctenoph.o.r.es_) and give rise to the larger, more brilliant flashes of light often seen in the wake or about the sides of a steamer at night. The former are various species of dinoflagellates or cystoflagellates such as _Noctiluca_ (just visible to the naked eye) which collect at the surface of the sea and often increase in such numbers that the water is colored by day (usually pink or red) and shines like a sheet of fire when disturbed at night.

Although _Noctiluca_ was recognized as a luminous animal in 1753 by Baker, the light of the sea was a mysterious phenomenon to the older observers. MacCartney, speaking before the Royal Society in 1810, outlines the various older theories as follows: "Many writers have ascribed the light of the sea to other causes than luminous animals.

Martin supposed it to be occasioned by putrefaction; Silberschlag believed it to be phosphoric; Prof. J. Mayer conjectured that the surface of the sea imbibed light, which it afterwards discharged. Bajon and Gentil thought the light of the sea was electric, because it was excited by friction.... I shall not trespa.s.s on the time of the Society to refute the above speculations; their authors have left them unsupported by either arguments or experiments, and they are inconsistent with all ascertained facts upon the subject. The remarkable property of emitting light during life is only met amongst animals of the four last cla.s.ses of modern naturalists, viz., mollusca, insects, worms, and zoophytes." MacCartney recognized the true cause of the light, although he had little idea of the vast number of marine forms which are luminous and omits entirely any reference to the fishes, many of which produce a light of their own when living, apart from any bacterial infection.

A survey of the animal kingdom discloses at least 36 orders containing one or more forms known to produce light and several more orders containing species whose luminosity is doubtful. In the plant kingdom there are two groups containing luminous forms. The distribution of luminous organisms is brought out in the accompanying cla.s.sification of plants and animals. Those orders are printed in italics which contain species whose self-luminosity is fairly well established. It will be noted that further subdivisions into orders is not given in cla.s.ses of animals which lack luminous forms.

TABLE I

_DISTRIBUTION OF LUMINOUS ORGANISMS IN PLANT AND ANIMAL KINGDOMS_

PLANT KINGDOM

I. _Thallophyta_ Algae Cyanophyceae (Blue-green Algae) Chlorophyceae (Green Algae) Phaeophyceae (Brown Algae) Rhodophyceae (Red Algae) Lichenes (Lichens, symbiotic growth of algae and fungi) _Fungi_ Myxomycetes (Slime moulds) _Schizomycetes_ (Bacteria) _Bacterium_, _Photobacterium_, _Bacillus_, Pseudomonas_, _Micrococcus_, _Microspira_, _Vibrio_.

Phycomycetes (moulds) Ascomycetes (Sac fungi, yeasts, some moulds) _Basidiomycetes_ (s.m.u.ts, rusts, mushrooms) Ustilaginae (s.m.u.ts) Uridineae Auriculariae (Judas ears) Tremellineae (Jelly fungi) _Hymenomycetes_ (Mushrooms) _Agaricus_, _Armillaria_, _Pleurotus_, _Pa.n.u.s_, _Mycena_, _Omphalia_, _Locellina_, _Marasinium_, _c.l.i.tocybe_, _Corticium_.

Gasteromycetes (Stinkhorns and puff-b.a.l.l.s)

II. Bryophyta Hepaticae (Liverworts) Musci (Mosses)

III. Pteridophyta Equisetineae (Horsetails) Salviniae (Salvinia, Marsilia, etc.) Lycopodineae (Club Mosses) Filicineae (Ferns)

IV. Spermatophyta Gymnospermae (Cycads, Ginkgo, Conifers) Angiospermae (Mono- and Dicotyledonous flowering plants).

ANIMAL KINGDOM

I. _Protozoa._ (One-celled animals) _Sarcodina_ Rhizopoda Heliozoa _Radiolaria_ _Thalla.s.sicola_, _Myxosphaera_, _Collosphaera_, _Collozoum_, _Sphaerozoum_.

_Mastigophora_ Flagellata Choanoflagellata _Dinoflagellata_ _Ceratium_, _Peridinium_, _Prorocentrum_, _Pyrodinium_, _Gonyaulax_, _Blepharocysta_, _Amphidinium_, _Diplopsalis_, _Cochlodinium_, _Sphaerodinium_, _Gymnodinium._ _Cystoflagellata_ _Noctiluca_, _Pyrocystis_, _Leptodiscus_, _Craspedotella._ Sporozoa Infusoria

II. Porifera (Sponges) Calcarea Hexactinellida Desmospongiae

III. _C[oe]lenterata_ _Hydrozoa_ (Hydroids and Jelly-fish) _Leptomedusae_ or _Campanulariae_ Medusa form--_Eutima_, _Phyalidium_ (_Oceania_).

Hydroid form--_Aglaophenia_, _Campanularia_, _Sertularia_, _Plumularia_, _Cellularia_, _Valkeria_, _Obelia_, _Clytia_.

_Trachomedusae_ _Geryonia_, _Lyriope_, _Aglaura_ _Narcomedusae_ _Cunina_ _Anthomedusae_ or _Tubulariae_ Medusa form--_Thaumantias_, _Tiara_, _Turris_, _Sarsia_.

Hydroid form--?

Hydrocorallinae _Siphonophora_ _Abyla_, _Praya_, _Diphyes_, _Eudoxia_, _Hippopodius._ _Scyphozoa_ (Jelly-fish) Stauromedusae Peromedusae _Cubomedusae_ _Carybdia_ _Discomedusae_ _Pelagia_, _Aurelia_, _Chrysaora_, _Rhizostoma_, _Cyanaea_, _Dianea_, _Mesonema_.

_Actinozoa_ (Corals, Sea-fans, Sea-pens, Sea-anemones) Actinaria Madreporareia Antipatharia _Alcyonaria_ _Alcyonium_, _Gorgonia_, _Isis_, _Mopsea_ _Pennatulacea_ _Pennatula_, _Pteroides_, _Veretillum_, _Cavernularia._ _Funicularia_, _Renilla_, _Pavonaria_, _Stylobelemon_, _Umbellularia_, _Virgularia?_ _Ctenophora_ (Comb-jellies) _Cydippida_ _Pleurobranchia_.

_Lobata_ _Mnemiopsis_, _Bolinopsis_, _Leucothea_ (_Eucharis_).

_Cestida_ _Cestus_.

_Beroida_ _Beroe._

IV. Platyhelminthes Turbellaria (Flat-worms) Trematodes (Parasitic flat-worms) Cestodes (Tape-worms) Nemertinea (Nemertines)

V. Nemathelminthes Nematoda (Round worms) Gordiacea (Hair worms) Acanthocephala (Acanthocephalids) Chaetognatha (Sagitta)

VI. Trochelminthes Rotifera (Wheel animalcules) Gastrotricha (Chaetonotus) Kinorhyncha (Echinoderes)

VII. _Molluscoidea_ _Bryozoa_ (Corallines) Entoprocta _Ectoprocta_ _Membranipora_, _Scrupocellaria_, _Retepora?_ _Fl.u.s.tra?_ Brachiopoda (Lamp sh.e.l.ls) Phoronidea (Phoronis)

VIII. _Annulata_ Archiannelida (Primitive worms, including Dinophilus) _Chaetopoda_ (True worms) _Polychaeta_ _Chaetopterus_, _Phyllochaetopterus_, _Telepsaris_, _Polynoe_, _Acholoe_, _Tomopteris_, _Odontosyllis_, _Lepidonotus_, _Pionosyllis_, _Phyllodoce_, _Heterocirrus_, _Polyopthalamus?_ _Oligochaeta_ _Lumbricus_, _Photodrilus_, _Allolobophora_ (_Eisemia_), _Microscolex_, _Nonlea_, _Enchytraeus_, _Octochaetus_.