Volume 12, Bulletins 146-156. (146) Studies on the Development of Butter Cultures from Mixtures of Organisms; (147) Methods for Determining Carbon Dioxide Production in Soils; (148) Some Chemical and Bacteriological Effects of Various Kinds and Amounts of Lime on Certain Southern Iowa Soils; (149) Pathology of Fusarium niveum (EFS.) and the Development of Wilt Resistant Strains of Citrullus vulgaris (Schrad.); (150) Length and Floor Construction of Dairy Stalls; (151) Studies on the Change in Nectar Concentration Produced by the Honeybee, Apis mellifera; (152) Factors Influencing Egg Production: III. The Association of the Date of Hatch with Date of First Egg, Sexual Maturity and Egg Production in S. C. White Leghorns; (153) Selection for Resistance to Fowl Typhoid in the Chicken with Reference to Its Inheritance; (154) Normal Growth in Dairy Cattle; (155) Relationship of Acetylmethylcarbinol and Diacetyl to Butter Cultures; (156) Economic Analysis of Farm Mortgages in Story County, Iowa, 1854–1931