The Nature of Animal Light - Tapa blanda

Excerpt: ... is sprinkled over the surface of water, it goes into solution and leaves luminous diffusion and convection trails plainly visible in the water. Many luminous marine forms give off a phosphorescent slime when they are handled, which adheres to the fingers. It is not surprising that this luminous matter should have early received a name. In 1872, Phipson called it noctilucin and described some of its properties. He regarded the luminous matter which can be scraped from dead fish (luminous Pg 102 bacteria) and the mucous secretion of Scolopendra electrica or the luminous matter of the glowworm to be this material, noctilucin, which, "in moist condition, takes up oxygen and gives off CO2 and when dry appears like mucin." Phipson says that it forms an oily layer over the seas in summer (he probably refers to masses of dinoflagellates), is liquid at ordinary temperatures and less dense than water, smells a little like caprylic acid, is insoluble in water but miscible with it, insoluble in alcohol and ether, dissolves with decomposition in mineral acids and alkalies and contains no phosphorus. We can see from this description that the word "noctilucin" does not indicate a chemical individual, but it is the earliest attempt to definitely designate the luminous substance. The idea of a definite substance oxidizing and causing the light has been upheld by a number of investigators, and many years later Molisch called this substance the photogen. He contrasts the "photogen theory" with certain other views of light production, which may be spoken of as "vital theories," notably those of Pfluger (1875), who looked upon luminescence as a sign of intense respiration, and of Beijerinck (1915), who regarded the light as an accompaniment of the formation of living matter from peptone. Fortunately biological science has advanced beyond the stage where a living process can be explained by calling it a vital process, and we must fall back upon the idea of a...