Contents

18 March 1994
Vol 263, Issue 5153

About The Cover

The circadian rhythm in asexual reproduction in the bread mold Neurospora crassa is illustrated by alternating growth rings of surface mycelia (red) and aerial hyphae (blue and yellow). Aerial hyphae extend above the growth surface to produce asexual spores. Studies of this rhythm have authenticated an initial gear in a circadian clock and suggest the algorithm by which such clocks may be assembled. See page 1578; related Reports on pages 1603 and 1606 and Perspective on page 1570. [Image: Reed Detar. Colorization:Jay C. Dunlap]