an international journal Volume 135 JAMES F. SELGRADE AND JAMES H. RoBerDs (Raleigh, North Carolina) Lumped-Density Population Models of Pioneer—Climax Type and Stability Analysis of Hopf Bifurcations N. JEANPRETRE AND P. G. H. CLARKE (Lausanne, Switzerland), AND J.-P. GABRIEL (Fribourg, Switzerland) Competitive Exclusion Between Axons Dependent on a Single Trophic Substance: A Mathematical Analysis Anup Dewanii (Calcutta, India), E.G EorG LUEBECK, AND SURESH H. MOOLGAVKAR (Seattle, Washington) A Biologically Based Model for the Analysis of Premalignant Foci of Arbitrary Shape EDWARD POLLAK (Ames, lowa) AND MUHAMAD SABRAN (Banjarbaru, Indonesia) On the Theory of Partially Inbreeding Finite Populations. IV. The Effective Population Size for Polyploids Reproducing by Partial Selfing EKATERINA M. MYASNIKOVA (St. Petersburg, Russia), SVETLOZAR T. RACHEV (Santa Barbara, California), AND ANDRE) Yu. YAKOVLEV (Columbus, Ohio) Queueing Models of Potentially Lethal Damage Repair in Irradiated Cells D. K. BHATTACHARYA AND S. BEGUM (Calcutta, India) Bionomic Equilibrium of Two-Species System. I CHRISTOPHER J. PoORTIER (Research Triangle Park, North Carolina), ANNETTE Kopp-SCHNEIDER (Heidelberg, Germany), AND CLAIRE D. SHERMAN (Research Triangle Park, North Carolina) Calculating Tumor Incidence Rates in Stochastic Models of Carcinogenesis BERNHARD SULZER AND ALAN S. PERELSON (Los Alamos, New Mexico) Equilibrium Binding of Multivalent Ligands to Cells: Effects of Cell and Receptor Density H. M. BYRNE AND M. A. J. CHAPLAIN (Bath, United Kingdom) Growth of Necrotic Tumors in the Presence and Absence of Inhibitors Book REVIEW JOHN L. SpouGE (Bethesda, Maryland) Information Theory and Molecular Biology (Hubert P. Yockey) Elsevier