Contents

30 April 1965
Vol 148, Issue 3670

About The Cover

Ping pong balls used as a model of yellow mosaic virus in the turnip. Partial rotation and superimposition of photographs of such a model yield information about the radial symmetry of the degree of rotation corresponds exactly with a regularly repeating pattern around its center, then the result is a more prominent version of the original; is not, then, as with this model, the result shows no resemblance to the original. See page 638.