A Letter From The Publisher, Jul. 14, 1958

THE lacy pattern of little round balls in the background of this week's cover is from a deoxyribo-nucleic-acid molecule model built at Manhattan's Sloan-Kettering Institute. The grey balls represent carbon atoms; blue is phosphorous; yellow is nitrogen; red is oxygen; white is hydrogen. Molecules do not look like this, of course. The atoms in them are much too small to be seen, even with an electron microscope. The pattern shown is a small part, somewhat simplified, of the DNA molecule, which geneticists now believe is the carrier of heredity and the chemical master of all life. If all of this seems...