Science: Euglena Muscles In

Chlorophyll would be a monopoly of the plant kingdom except for the muscling-in of a little-known group of microscopic water animals.* Unlike the 850,000 other species of animals, which live parasitically off the food-making ability of the plant world, these little creatures contain chlorophyll and hence can synthesize food out of water, carbon dioxide in the presence of light. And unlike any of the 250,000 species of plants, one of these animals—Euglena rubra by name—changes its color, now red, now green, to control the amount of light it uses. This phenomenon was explained last week in Physiological Zoology by Leland P. Johnson of Drake University and Theodore Louis Jahn of the University of Iowa.

Zoologists Johnson and Jahn studied these microscopic protozoa in Iowa ponds for five summers, found they were reddest when the temperature was a sunny 90° or more. Taken to a dark laboratory, the animals turned green, then turned red again not only on exposure to light but to heat. Reason: migration of a red pigment between the animal’s interior and its surfaces. Its purpose: to protect the chlorophyll granules from an overload of light, which would destroy the pigment. Besides making food like plants, Euglenae also can eat like animals.

*These popular little creatures are claimed both by zoologists and botanists.