agar to which indole-3-acetic acid (IAA) had been added, (3) on sucrose mineral agar after inoculation of the fragment with crown-gall bacteria. Five aspects of growth were measured: increase in length, breadth, fresh and dry weight, and production of adventitious roots. Sunflower seeds var. Russian Giant were sterilized by being immersed for two minutes in a 1% solution of sodium hypochlorite. They were then -washed in three changes of sterile distilled water and soaked in water for two hours. The embryos were then removed from their seed coats, transferred aseptically to tubes (25 mm. ? 200 mm.) each containing 10 ml. nutrient agar (2% sucrose + White's mineral solution+ 1% agar) and cultured at 25? C in continuous light from four 40 watt fluorescent lamps. When the hypocotyls attained a length of 100 mm. the embryos were drawn out of their tubes and the hypocotyls severed just above the root and immediately below the cotyledons. The hypocotyls were cut into segments five mm. long which were placed radicle end uppermost in agglutination tubes (10 mm. ? 75 mm.) containing three ml. of nutrient agar. They were incubated for 10 days in darkness at 25? C, then removed, photographed, and weighed. The photographs were made by projecting the image of the fragment through an enlarger onto printing paper. The magnification used was 1.7 diameters in most instances. The length and breadth of the fragment and the size of the tumors were estimated from these shadowgraphs. Agrobacterium tumefaciens, strain B.P., was used in these experiments, suspensions being prepared from 24 hour slopes. Indoleacetic acid was incorporated into the nutrient agar for the hypocotyl fragments after autoclaving. Growth of hypocotyl fragments on sucrose mineral agar Ten sunflower hypocotyls, each about 100 mm. long, were divided into 20 segments five mm. long; and every alternate fragment beginning with