From the September 3, 1932, issue


Manufacturers of modern jewelry might well turn to the larvae of the caddis fly for effective models for small containers–tiny perfume bottles, say, or lipstick cases. These water-dwelling “worms” build mosaic coverings for the little cylindrical houses they spin for themselves, taking bits of sand and gravel from the streambed and stopping the posterior ends with larger pebbles. These mosaic cases serve at once as camouflage and armor.

Artists of another group–designers of print goods–might also learn from the caddis fly larvae, as Cornelia Clarke has shown in arranging the group of nine shown on the cover of this issue of the Science News Letter.


X-rays can speed up the processes of evolution, and they can also reverse its direction, undoing changes that they themselves have caused. This was announced at the meeting of the Sixth International Congress of Genetics at Ithaca, N.Y., by Dr. N.W. Timoféeff-Ressovsky.

The discovery of the evolution-reversing power of X-rays was made as the result of researches conducted at the Kaiser Wilhelm Institute for Brain Research in Berlin. It agrees with similar results obtained by other workers in the same field.

Dr. Timoféeff-Ressovsky worked with fruit flies, classic experimental animals in genetics, using the X-ray technique for producing hereditary changes developed by Prof. H.H. Muller of the University of Texas. Bombardment of their reproductive cells with X-rays caused marked changes in color, shape, size, etc., of eyes, bristles, and other body parts in their offspring. Dr. Timoféeff-Ressovsky discovered that a second bombardment inflicted on these same offspring would often reverse the changes, causing a third generation to have a normal appearance again.

From his results he argued that the effects of an X-ray bombardment are not merely destructive of the genes, as has frequently been stated. He pointed out that while the production of an abnormality might look like a destructive effect, the return to normalcy by a second X-ray bombardment makes this conclusion absurd.


The bald or white-headed eagle, chosen by the founders of the Republic as the national emblem, has been cheated out of a place on the Washington memorial 25-cent piece just issued. The bird that roosts on the lictor’s fasces on the reverse of the new coin has feathered “trousers” coming clear down to his feet, which marks him as a golden eagle. The golden eagle is native to the Old World as well as to America and is displayed by the coats-of-arms of several European nations. The bald eagle, a strictly American bird, has the “trousers” only in his juvenile state; when mature he is bare-shanked.

The bald eagle is correctly shown on all save one of the other U.S. coins where an eagle appears at all. The other exception is the half-dollar that came into use just before the World War, on which a “trousered” golden eagle is shown. On all the older coins, the bird is unmistakably a bald eagle.

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