Page:Popular Science Monthly Volume 69.djvu/226

these structures to the action of chemical agents, not ordinarily encountered by the elements in question, at a time before fertilization occurred. The tests were planned to include the use of a solution of high osmotic value, and mineral compounds, some of which are toxic in concentrated solutions and stimulating in the proportions used. The probability of success would be heightened with the number of ovules contained in any ovary operated upon, and therefore the common evening-primrose, Œnothera biennis, Raimannia odorata a relative of it Fig. 8. Mutant of the Common Evening Primrose, induced by Treatment of Ovules with Solutions of Zinc Sulphate. and a member of the same family, Begonia, Cleome, Abutilon, Sphæralcea and Mentzelia and others were experimented upon. Without recourse to the detail of the work, it may be stated that the use of radium preparations, sugar solutions (10 per cent.), and solutions of calcium nitrate one part in one to two thousand of distilled water with capsules of Raimannia odorata, and zinc sulphate in a stronger solution used with Œnothera biennis, was followed by very striking results. In the first-named plant, there appeared in the progeny obtained from a few capsules of one individual, several individuals which were seen to differ notably from the type with the appearance of the cotyledons, and, as development proceeded, it was evident that a mutant had appeared following the injections and nowhere else, and thus to have some direct relation to the operation. The characters of the newly arisen form were so strikingly aberrant as to need no skill in their detection. The parent was villous-hairy, the mutant entirely and absolutely glabrous, the leaves of the parent have an excessive linear growth of the marginal portions of the leaf-blades and hence become fluted; the excess of growth in the mutant lies along the midrib and the margins become revolute. The leaves are widely different in width, those of the mutant being much narrower. The parental type is of a marked biennial habit and near the close of the season the internodes formed are extremely short, which has the result of forming a dense rosette; the mutant forms no rosette by reason of the fact that the stem does not cease, or diminish its rate of elongation, and hence presents an elongated leafy stem, which continues to enlarge as if perennial. The first generation