BOTANICAL RESEARCH — MACDOUGAI,. I29 



No real actuating cause for discontinuous variation in a hereditary strain 

 having been found, attention was directed to the possibility of inducing 

 changes in the hereditary elements in such a manner that the qualities trans- 

 mitted would be altered or destroyed. A theoretical consideration of the 

 subject seemed to indicate that the changes constituting the essential opera- 

 tion of mutation ensued in a stage previous to the reduction divisions in the 

 embryo-sac, or the pollen mother cells. It was planned therefore to subject 

 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, Oenothera biennis, 

 Raimannia odorata, a relative of it and a member of the same family, Begonia, 

 Cleome, Ahiitilon, Sphceralcea, Mentzelia, and others were experimented 

 upon. Without recourse to the detail of the work, it may be stated that the 

 use of 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 Oenothera 

 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 of the derivative came to bloom at the beginning of the 

 present year, and bare mention of the existence of the derivative was given 

 in a lecture before the Barnard Botanical Club at that time. The real value 

 of the changes induced, however, lay in the transmissibility of the newly 

 exhibited qualities. The flowers of the mutant were closely guarded and as 



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