Popularization

How do the firefly and the glowworm blink their lights? How does the jellyfish called ctenophore and the tiny, multitudinous noctiluca flash in the sea? And two score other fish, insects, plants, and bacteria?

To tell an inquisitive public, New York's American Institute last week conducted another of its popular lectures on scientific topics. Speaker was Edmund Newton Harvey, professor of physiology at Princeton and authority on chemiluminescence for the National Research Council.* After explaining that luminescence in living matter is not phosphorescence and has nothing to do with phosphorus, he had a simple story to tell.

That is, about 40 living forms secrete a substance called luciferin. In the presence of moisture luciferin oxidizes, forming oxy-luciferin, the substance which actually glows. As oxy-luciferin glows it loses its oxygen and returns to luciferin, which after a short rest may be oxidized again.

The question of whether man shall ever be able to reproduce living light, which is at least twice as efficient as best artificial light, becomes the question whether chemists will ever be able to synthesize the protein luciferin. Dr. Harvey thought that "that will come in the future. We now synthesize fats, sugars, and some of the polypetides." Luciferin seems to be either a peptone or a proteose.

* In 1913-14 he explored the Great Barrier Reef, 1,200-mi. coral band fringing northeast Australia, for the Carnegie Institution of Washington. Leader of the expedition was Dr. C. M. Yonge, Englishman, whose essays on marine science, Vueer Fish, Brentano's has just published ($2.50). Mrs. Harvey, as Dr. Ethel Nicholson Browne, taught biology at Wellesley and Cornell until their marriage in 1916. They live at Princeton, have two sons.