Sex Life of Achlya

The existence of sex hormones is one of the most widely-known discoveries of modern biology. Androsterone and testosterone make a man manly, progesterone and estrone make a woman womanly. But in man and other highly evolved animals, the ordinary processes of life depend on other hormones which are non-sexual--such as insulin, the sparkplug hormone from the pancreas. Growth, according to the Carnegie Institution's Oscar Riddle, is due to a combined action of two pituitary hormones, prolactin and thyrotropin.

Growth hormones have been discovered in plants. The major ones are "Auxin A," "Auxin B" and "Heteroauxin." Academic research on plant-growth hormones, mainly done within the past decade, has plowed its ground so well that commercial hormone preparations are now available to nurserymen to stimulate root growth in cuttings.

Last week Biologist John Robert Raper of Harvard turned up with something new under the scientific sun--a clear demonstration of the function in plants of hormones which are not growth hormones but sexual. The host: Achlya ambisexualis, a minute water fungus which Dr. Raper discovered some time ago in the Charles River.

Achlya ambisexualis elaborates no less than four sex hormones which diffuse through the water, from male to female and vice versa. Hormone A, from the female, causes the male fungus to put out shoots. The shoots produce Hormone B, which goes back to the female, initiates the growth of egg-containers. The egg-containers manufacture Hormone C, which attracts the male shoots so that contact is effected (up to ranges of one-third inch). Hormone D, from the male shoots, stops the growth of the female egg-containers when they are of proper size.

Dr. Raper was careful to point out that thi functioning of sex hormones in Achlya ambisexualis does not imply anything similar in other plants.* Even so hormonic sex can no longer be regarded as the exclusive cock-a-doodle-doo of the animal kingdom.

*Many plants are cross-fertilized, but by wind-borne or insect-borne pollen--the equivalent of sperm in men and animals.

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