ALSO AVAILABLE ONLINE: http ://www.elsevier.nl/locate/bba or http ://www.elsevier.com/locate/bba ContentsDirect, the free e-mail alerting service, delivers the table of contents for this journal directly to your PC, prior to publication. The quickest way to register for ContentsDirect is via the Internet at: http://www.elsevier.nl/ locate/ContentsDirect. If you don’t have access to the Internet you can register for this service by sending an e-mail message to cdsubs @elsevier.co.uk — specifying the title of the publication you wish to register for. 0005-2736 (19980902) 1373:2;1-T