Volume 19, Bulletins 210-221. (210) Effect of Electric Current on Certain Crop Plants; (211) Changes in the Acetylmethylcarbinol Plus Diacetyl Content of Butter; (212) Utilization of Heat from Electric Surface Units by Certain Cooking Utensils; (213) Starting Baked Products in Cold Versus Preheated Ovens; (214) Chemistry of Butter and Butter Making: III. The Relationships Between (1) the Percentage Fat and (2) the Protein Percentages of Cream and the Churning Loss; (215) Care of Meat in the Household Refrigerator; (216) Crown Infection of Corn by Diplodia zeae; (217) Occurrence of Azotobacter in Iowa Soils and Factors Affecting Their Distribution; (218) Influence of Size of Brood Cell Upon the Size and Variability of the Honeybee; (219) Effect of Injury in Imitation of Hail Damage on the Development of Small Grain; (220) Regeneration in Various Types of Apple Wood; (221) Influence of the Type of Butter Culture and Its Method of Use on the Flavor and Keeping Quality of Salted Butter