From the Editors. 207

Carver, G.W. Plants as modified by man. 209

Arthur, J.C. On the structure of Echniocystis lobata. 219

Rubio-Moran, R., W.A. Rowley, and J.R. Coats. Effect of permetherin and malathion on Aedes trivittatus and Culex pipiens pipiens. 235

Wessel, R. I. Athletics and their effects on female teachers in public schools in Iowa. 245

Klemke, E. D. Some misinterpretations of Karl Popper. 253

Pohl, R.W. and M.C. Albertsen. Interspecific hybrids of Zea mays and Z. diploperennis. 257

Hvisdos, M.A an S.G. Clark. Young children's concepts of human birth. 261

Stockdale, D.F. and D. Pease. Social interaction n same-sex and opposite-sex dyads among school-age children. 267

Snyder, J.B., A.M. Fanslow, and H.P. Njus. Food consumption patterns of expanded food and nutrition education program participants in Iowa. 279

Noland, S. Some major deterrents to the decentralization of universities in Iran: The case of Farabi University. 287