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The Origin of the Electric Organs in Scopus Guttatus

professor, fishes and electricity


Living organisms, aside from expending energy in the growth, differ entiation, and reproduction of their bodies and in secreting many sub stances useful in the preservation of their lives, may also release energy in the form of motion, electricity, heat, and light, all of which may play a more or less important part in the maintenance of life. Of these powers, that of producing electricity specifically and in quantities large enough to be of use to the organism is confined to seven groups of fishes, two of which are elasmobranchs and five teleosts. The same power has been reported to be present in a snail and in some insects, but these reports have not been confirmed. It seems clear that among the fishes the power to produce electricity has been developed inde pendently in the seven groups mentioned. All the activities of cells, such as secretion, motion, or nerve-conduction are accompanied by the release of a very small amount of electric energy, which apparently can not be of any possible use to the animal. Are the powerful electric discharges, sometimes over 100 volts in strength, which occur in these seven groups of fishes the result of evolutionary processes that first took their origin in the very minute electric discharge of the ordinary forms of tissue-cells? A beginning to an answer to this question may be made by studying the structure of the electric organs, and particularly their morphologi cal and cytological development in the ontogeny of the forms. This

the writer has attempted to do, as suggested by Professor Ulric Dahl gren, of Princeton University, in the case of the remarkable electric organ of Astroscopus guttatus and Astroscopus y-grcecum. I wish here to express my gratitude to Professor Dahlgren for his generous offer of the material, for his kindly direction of the problem, and for his most valuable criticisms. I wish also to thank Professor E. G. Conklin, of Princeton University, and Professor E. B. Wilson, of Columbia University, for reading and criticizing the paper. The expenses of collecting the material for this work were met by donations extending over a series of years from the Carnegie Institution of Wash ington, through the kindness and interest of Dr. A. G. Mayer.