XVI. Origin of the peloric toad-flax. 459
Sudden and frequent origin in the wild state. Origin in the experiment-garden. Law of repeated mutations. Probable origin of other pelories.
XVII. The production of double flowers. 488
Sudden appearance of double flowers in horticulture. Historical evidence. Experimental origin of Chrysanthemum segetum plenum. Dependency upon nourishment. Petalody of stamens.
XVIII New species of Oenothera. 516
Mutations of Oenothera lamarckiana in the wild state near Hilversum. New varieties of O. laevifolia, O. brevistylis, and O. nanella. New elementary species, O. gigas, O. rubrinervis, albida, and oblonga. O. lata, a pistillate form. Inconstancy of O. scintillans.
XIX. Experimental pedigree-cultures. 547
Pedigree of the mutative products of Oenothera lamarckiana in the Botanical Garden at Amsterdam. Laws of mutability. Sudden and repeated leaps from an unchanging main strain. Constancy of the new forms. Mutations in all directions.
XX. Origin of wild species and varieties. 576
Problems to solve. Capsella heegeri. Oenothera biennis cruciata. Epilobium hirsutum cruciatum. Hibiscus Moscheutos. Purple beech. Monophyllous strawberries. Chances of success with new mutations.