Observations on Photophores and Luminescence in the Teleost Porichthys

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Abstract
Porichthys myriaster is a shallow-water teleost possessing numerous photophores on head and trunk. These are embedded in the dermis and consist of a lens, layer of photogenic cells, and reflecting sheath. The photophore receives a nerve and blood-vessels which proceed to the photogenic tissue. The photogenic cells are finely granular and stain poorly. Luminescence in the living fish was evoked by electrical excitation and injection of adrenaline. When the nerve-cord was stimulated by electric shocks, the photophores lit up after a latent period of 7-10 sec. With localized stimulation a response was still obtained from all the photophores of the body after transection of the nerve-cord and arrest of circulation. Injection of adrenaline into the heart caused widespread luminescence in 2 min. The pattern of innervation of the photophores in teleosts suggests an autonomic supply. It is concluded that the photophores of Porichthys are probably innervated by the sympathetic system. Efferent fibres may be adrenergic. If the adrenals are involved, their effect is secondary, following nervous excitation.