Vol. 6, No. 11, HILGARDIA, a journal of agricultural science published by the California Agricultural Experiment Station, replaces the Technical Papers Nos. 1 to 20. The journal includes studies on agricultural topics such as the growth of orange trees, citrus diseases, rootstocks, apple tissue darkening, plant respiration, soil reclamation, and more. The journal also features a detailed article by Max Kleiber on body size and metabolism, discussing the surface law, which states that basal metabolism is proportional to body surface area. Kleiber reviews the historical development of the surface law, its theoretical weaknesses, and empirical evidence from various studies. He argues that while the surface law has been widely used, recent data suggest that metabolism is more closely related to body weight raised to the 3/4 power rather than body surface area. Kleiber also explores theories explaining the relationship between body size and metabolism, including heat loss, nutritive surfaces, and blood circulation. He concludes that the surface law is not a matter of tissues or cells but of the animal as a whole, with the nervous and endocrine systems regulating blood flow and metabolism. The article highlights the importance of considering the overall organism rather than isolated tissues or cells in understanding the relationship between body size and metabolism.Vol. 6, No. 11, HILGARDIA, a journal of agricultural science published by the California Agricultural Experiment Station, replaces the Technical Papers Nos. 1 to 20. The journal includes studies on agricultural topics such as the growth of orange trees, citrus diseases, rootstocks, apple tissue darkening, plant respiration, soil reclamation, and more. The journal also features a detailed article by Max Kleiber on body size and metabolism, discussing the surface law, which states that basal metabolism is proportional to body surface area. Kleiber reviews the historical development of the surface law, its theoretical weaknesses, and empirical evidence from various studies. He argues that while the surface law has been widely used, recent data suggest that metabolism is more closely related to body weight raised to the 3/4 power rather than body surface area. Kleiber also explores theories explaining the relationship between body size and metabolism, including heat loss, nutritive surfaces, and blood circulation. He concludes that the surface law is not a matter of tissues or cells but of the animal as a whole, with the nervous and endocrine systems regulating blood flow and metabolism. The article highlights the importance of considering the overall organism rather than isolated tissues or cells in understanding the relationship between body size and metabolism.