Correction

ECOLOGY. For the article “Water-borne cues induce chemical defense in a marine alga (Ascophyllum nodosum)” by Gunilla B. Toth and Henrik Pavia, which appeared in number 26, December 19, 2000, of Proc. Natl. Acad. Sci. USA (97, 14418–14420; First Published December 5, 2000; 10.1073/pnas.250226997), the authors note the following correction. The sentence on lines 8 and 9 in the second column on page 14419 should read “. . . and the wet-weight change (WWC) of each agar disc was calculated by subtracting the start weight from the stop weight.”