1. Root-callus cultures of five species of southern pines-pond (Pinus serotina Michx.), longleaf (Pinus palustris Mill.), slash (Pinus elliottii Englm.), loblolly (Pinus taeda L.), and sand (Pinus clausa [Chapm.] Vasey)-were established on agar containing modified Heller's solution and were maintained by serial transfer. Sand pine root callus was selected for the studies reported here. 2. Manometric experiments with respiratory inhibitors revealed inhibition of respiration by cyanide, iodoacetic acid, and fluoride, but not by fluoroacetate or malonic acid, in buffer solutions of pH 5.4. 3. Polyphenol oxidase, peroxidase, and catalase, but not cytochrome oxidase, activities could be demonstrated in tissue extracts. 4. Radioactive glucose, formate, pyruvate, glutamate, citrate, and succinate feedings demonstrated that the utilization of these compounds by sand pine callus cultures was not radically different from that of other higher plants. 5. The initial products accumulating label in the dark from C14O2, detected in our chromatographic system, were malate and aspartate. Subsequent distribution of activity was into members of the citric acid cycle and transamination products of oxalacetate and α-ketoglutaric acid.