Frederick Currey

“ The case of the Cycadcæ he considers very conclusive, as showing that the development in the embryo-sac can only proceed up to the point at which the stimulus to the commencement of the formation of an embryo must be given, and that where this stimulus is wanting, the germinal vesicle, even in vigorous seeds, exhibits no further development. ”

“ The plants were sown in April in the open air; the male plants which appeared were destroyed, and two female plants only allowed to stand, which were carefully examined every two days, in case any male blossoms should be overlooked. Each year seeds were ripened, from which both male and female plants were raised. Bernhardi was satisfied that at the time of the experiments no male plants were in flower near the spot where they were carried on, and consequently that accidental impregnation by pollen grains carried by the wind, or by insects, was out of the question. ”

“ He considers monæcious and diæcious plants to be especially likely to have led to deceptions, because sufficient care was not taken to examine each individual flower— a precaution which is necessary on account of the frequent occurrence of accidental anthers in the female flowers, and because monæcious and diæcious plants produce a greater quantity of pollen than hermaphrodites, and consequently accidental impregnation by wind or insects is highly probable. ”

“ He found that female plants of Hemp planted in a place surrounded by high walls, and others cultivated in pots and placed in a greenhouse in a garden, also surrounded by high walls, produced a quantity of perfect seeds, although no male plants were near, and although the females were subjected to careful examination with a view to the detection of possible male organs. ”

“ Regel subsequently proceeds to detail his experiments on Mercurialis annua, from which he concludes that the previous observers who have imagined that they have procured perfect seeds without impregnation, have overlooked the very frequent occurrence of anthers in the so-called female flowers; and with regard to the persistence of the stigma, upon which Kadlkofer places so much reliance, as proving the fact of non-impregnation, a figture is given (after Nees) of the young fruit still surmounted, by the perfect stigma ”

“ Female plants raised from these unimpregnated seeds were set apart in the house of M. Decaisne, and so protected that M. Xaudin considers it altogether impossible that any pollen could have reached them; and although they were carefully examined by himself and M. Decaisne, no single male flower was ever discovered amongst the females. ”

“ A second experiment was made, in which the female plants were brought into flower six weeks before the time of flowering of the hemp in the open fields, and similar results were obtained.
De Marti [2] repeated the above experiment, and considered Spallanzani's observations imperfect. He was of opinion that male blossoms must have existed, which were overlooked by Spallanzani. Volta [3] also was unable to procure any perfect seeds from plants from which the anthers had been carefully removed. ”

“ Braun refers to some experiments of Schenk, made, during the three previous years, in the botanical garden at Wurzburg, and also to some observations of De Bary made at Freiburg. Schenk directed his attention to Cannabis sativa, Mercurialis annua, Ricinus communis, Momordica elaterium, and Cucurbita Pepo. De Bary speaks of Cannabis sativa alone. Both observers obtained only negative results, and the same was the case with some later observations upon Cannabis sativa and Mercurialis made by Schenk, and reported in the "Wurzburg Nat. Zeitschrift," Bd. 1. ”