EXTRACTS OF OVULAR TUMORS AND THEIR INHIBITION OF EMBRYO GROWTH IN DATURA

IT HAS BEEN SHOWN (Satina and Blakeslee, 1935) that most of the crosses in Datura fail to produce viable seeds. Although in most of the cases fertilization takes place, the embryo does not fully develop but dies approximately 3-4 weeks after fertilization. The innermost layer of the seedcoat (endothelium) proliferates in these cases and invades the embryo-sac cavity filling it with tumoral outgrowths. In previous papers (Rappaport, 1948; Satina et al., 1950) evidence was presented which indicated that tumoral tissue present in the ovules of incompatible Datura crosses contained a growth-inhibiting substance. To secure further information regarding this hypothetical substance, different extracts of the embryo-sac contents of these ovules were prepared. On account of the availability of flowers throughout the year and the relatively large size of the tumoral tissue, the incompatible cross D. inoxia 4n X 2n was chosen. Occasionally tumoral tissue of other crosses listed in table 2 of the previous paper (Satina et al., 1950) could be tested. D. inoxia 4n flowers were castrated before the anthers shed their pollen, and 2 or 3 days later they were pollinated with pollen from D. inoxia 2n. Approximately 1 month later, according to the season, the capsules were harvested. These contained three to ten seeds in which the embryo sacs contained tumoral tissue, a milk-like, cheese-like, or jelly-like mass. The latter was dissected under sterile conditions and brought into vials containing previously sterilized water. In general, the embryo-sac contents of five ovules of an incompatible cross were put into a vial containing 2.5 ml. of distilled water. The dissected tissues were left in their vials for extraction for 48-72 hr. under a constant temperature of ?22?C. After this period the extract was filtered under sterile conditions and added to cultures of embryos of D. stramonium which had been growing in vials for 14 days and which were selected for homogeneity and measured in the way described in a previous paper (Satina et al., 1950). WVith each experiment two series of embryos were used as controls. To one series no addition was made. To the other was added sterile water in