Evaluation of nutrient availability in soils, and prediction of yield response to fertilization. C.A. Black 1

Effects of organic mercury compounds on enzymatic oxidation of malic acid. James L. Hilton and Frederick G. Smith 13

Fungus leaf spots of brome grass in Iowa. Lois H. Tiffany 21

The leguminosae of the north-central United States II. Hedysareae. Duane Isley 33

Growth of crappies, bluegill, and warmouth in Lake Ahquabi, Iowa. Richard C. Hennemuth 119

Effect of fluorescent and incandescent light on temperatures in photoperiodic chambers. S.C. Wiggans and R.H. Shaw 139

Life history of the black bullhead, Ameiurus melas (Rafinesque), of Clear Lake, Iowa. John L. Forney 145