From the Editors. 391

Larkin, P.J. Somaclonal variation: history, method, and meaning. 393

Beversdorf, W.D. and L.S. Kott. An in vitro mutagenesis/selection system for Brassica napus. 435

Hanson, M.H., M.A. O'Connell, and C. Vidair. Regeneration of calli and plants following protoplast fusion in Lucopersicon.

Bagley, P.C. and N.L. Taylor. Evaluation of phosphorus efficiency in somaclones of red clover. 459

Orton, T.J. Genetic instability in celery tissue and cell cultures. 481

Note. 499

Book Review. 501