Bioluminescence

Dr. Edmund Newton Harvey was once reported eaten by cannibals near the Torres Strait south of New Guinea, but the U. S. Department of State later announced that the report was exaggerated. Having done biological research from Maine to Puget Sound, from Tortugas to California, in Naples, Bermuda, the Philippines, Java, The Netherlands East Indies, Dr. Harvey, safe & sound, is now a professor of biology at Princeton. His wife. Ethel Browne Harvey, is a distinguished biologist. For a quarter-century. Edmund Harvey has experimented much, read enormously, to learn all he could about the phenomenon of bioluminescence--production of light by living creatures. This week he publishes a summary called Living Light (Princeton University Press; $4).

Light is usually associated with heat. All solids begin to glow at 525DEG C. But many other agencies besides heat can produce light--rubbing, fracture, pounding, excitation by electricity or short-wave radiation, etc. Surgeon's tape emits a greenish glow when stripped from a roll. Lumps of sugar luminesce when rubbed together. Quartz pebbles shine when struck by a hammer.

When ozone is bubbled through a dilute pyrogallol solution, the liquid glows brightly though no heat is evolved. Not true is the common saying that scientists are still searching for "cold light." Fluorescent and vapor-discharge lamps (e.g., neon, sodium) are true "cold lights" in that heat is not what makes them shine.

Thousands of animal species scattered through 40 * also emit cold light.

They include sponges, jellyfish, earthworms, brittle stars, crustaceans, insects, spiders, molluscs, squid, marine worms, hydroids, siphonophores, sea pens, cteno-phores, corallines, myriapods, balanoglos-sids, ascidians, fish. There are also two kinds of luminous plants--certain bacteria and fungi. These are responsible for the dim shining of damp wood and stale meat, the ghastly glow occasionally seen on human corpses.

Emission of light by living things is a chemical reaction requiring oxygen. Many luminescent creatures secrete an easily oxidizable compound, luciferin, which is oxidized with the help of an enzyme, luciferase. The exact chemical nature of luciferin and luciferase varies from species to species--firefly luciferin, for example, is no good when mixed with luciferase from worms. The reaction may occur in special gland cells, or the animal may eject luminous material. Some deep-sea squid throw off luminous puffs to confuse attackers, but this dodge is not always effective.

Some deep-sea fish, such as the species Photoblepharon palpebratus of the Banda Islands, have headlights powered by luminous bacteria (see cut}. Photoblepharon has arranged a "symbiosis" (mutually profitable living together), providing the bacteria with food and fine living conditions in a sac near the eye. while the bacteria furnish the fish with lanterns.

Author Harvey scouts the prevalent notion that a firefly's light is "100% efficient." It is true that all a firefly's output goes into visible light--that is, none is wasted in invisible infrared or ultraviolet radiation--but a consequence is that the light is greenish and would be unpleasant for human use even if it could be duplicated. Moreover, the proportion of visible to total radiation is not the only criterion of efficiency. Another is the ratio of light produced to energy expended. Scientists have not succeeded in measuring this ratio in the firefly because of the intermittent flash, but Dr. Harvey declares it is "undoubtedly very low."

* The order is the next highest biological classification above the family. The order of primates, for example, includes the human family, also monkeys and apes.

This file is automatically generated by a robot program, so reader's discretion is required.