I like to point out that colchicine is not a mutagen in the classical sence, but used to induce polyploidy. However nowadays the much less toxic herbicide surflan ( chemical constituent oryzalin) is used for that purpose Ben J.M.Zonneveld Institute of Biology,Leiden University, Clusius lab Wassenaarse weg 64, 2333 AL Leiden, The Netherlands Zonneveld@rulbim.Leidenuniv.NL Fax: +31-71-5274999. min temp -10C (15F)