Volume 26, Bulletins 304-320. (304) Statistical Investigation of a Sample Survey for Obtaining Farm Facts; (305) Efficiency of Dairy Rations Containing Various Quantities of Grain; (306) Social and Ecological Patterns in the Farm Leadership of Four Iowa Townships; (307) Economic Problems of Low Income Farmers in Iowa; (308) Statistical Comparisons of Record-Keeping Farms and a Random Sample of Iowa Farms for 1939; (309) Twenty-one Years of Iowa Farm Records; (310) Ecology and Management of the mourning Dove, Zenaidura macroura (Linn.) in Cass County, Iowa; (311) Demand for Fats and Oils in the Soap Industry; (312) Factor in Oat Hulls Essential for the Growth of Chicks; (313) Problems of Beginning Farmers in Iowa; (314) Mycorrhizae and Phosphorus Nutrition of Pine Seedlings in a Prairie Soil Nursery; (315) Some Investigations on the Suitability of the Township as a Unit for Sampling Iowa Agriculture; (316) Chemistry of Butter and Butter Making: V. Methods for Determining the pH of Cream with Standardized Acidity and of Butter Made from this Type of Cream; (317) Development of a Bob-White Management Area in Southern Iowa; (318) Some Additional Lattice Square Designs; (319) Water Supplies of Butter Manufacturing Plants; (320) Analysis of Mink Predation Upon Muskrats in North-Central United States