. Botany for agricultural students . Botany. MUTATION IN THE EVENING PRIMROSE 529 the fuzz of a peach, sometimes arises as a branch of the Peach tree. Mutation in the Evening Primrose. — The Evening Primrose is especially noted because it has furnished much of the material upon which the mutation theory is founded. One of the diffi- culties in finding mutations is that any given species does not mutate all of the time but only at occasional periods. In 1886 De Vries began to search for species that were in the mutating period. The American Evening Prim- rose {Oenothera Lamarck- iana) {Fig. 472
. Botany for agricultural students . Botany. MUTATION IN THE EVENING PRIMROSE 529 the fuzz of a peach, sometimes arises as a branch of the Peach tree. Mutation in the Evening Primrose. — The Evening Primrose is especially noted because it has furnished much of the material upon which the mutation theory is founded. One of the diffi- culties in finding mutations is that any given species does not mutate all of the time but only at occasional periods. In 1886 De Vries began to search for species that were in the mutating period. The American Evening Prim- rose {Oenothera Lamarck- iana) {Fig. 472), also known as Lamarck's Evening Primrose, proved to be the species for which he was searching. He found a large number of plants of this species growing in an abandoned potato field at Hilversum, near Amsterdam. Among them he found some un- known and very distinct forms which apparently had come from seeds of the normal American Evening Primrose. Seeds were secured from the normal plants, and cul- tures were begun in the Botanical Garden at the University of Amsterdam. From the first sowing he obtained another new form. Through a series of pedigree cultures in- volving a number of generations, quite a number of distinct forms were obtained. Some of these distinctly new forms ap- peared repeatedly in the cultures, while others appeared only once, but they all bred true, thus producing offspring like them- selves. These new forms did not arise gradually but appeared suddenly and were so distinct from the American Evening Primrose, their parent, as to be called new Fig. 472. — Lamarck's Evening Primrose {Oenothera Lamarckiana), a mutating species. After De Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Martin, John N. (John Nathan), b. 1875. New York : John Wiley & Sons, Inc.
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