2o6 Heredity and Eugenics 



member of the same family, Begonia, Cleome, Abutilon, Sphaeralcea, 

 and Mentzelia, and others were experimented upon. Without recourse 

 to the detail of the work it may be stated that the use of radium prepara- 

 tions, sugar solutions (lo per cent), and solutions of calcivun nitrate, 

 of distilled water, with capsules of Raimannia odorala, and zinc sulphate 

 in a stronger solution used with Oenothera biennis (Fig. 71.4) was fol- 

 lowed by very striking results. In the first-named plant, there appeared 

 in the progeny obtained from a few capsules of one indi\ddual several 

 individuals w^hich 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, which thus had some direct relation to the operation. 

 The characters of the newly arisen form were so strikingly aberrant 

 as to need no skill in detection (Fig. ^iB). 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 t}^pe 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 con- 

 tinues to enlarge as if perennial. The first generation of the derivative 

 came to bloom; the flowers of the mutant were closely guarded and as 

 soon as seeds were obtained they were planted to obtain a second 

 generation. A few plants were obtained, which in every particular 

 conformed to the new type and exhibited no return to the parental 

 type. 



MacDougal's investigations, wherein were produced 

 modifications that have remained stable through four or 

 more generations, in Raimannia, Cereus, Penstemon, and 

 others, show fully that the method employed gives definite 

 changes in germinal constitution. 



