De Marti[1] 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[2] also was unable to procure any perfect seeds from plants from which the anthers had been carefully removed.
In 1837, Ramisch published some observations upon Mercurialis annua, with which he had been occupied for four successive years. The results were inconclusive, for although Ramisch procured seeds, both with and without embryos, he admits that in some of the female plants upon which he experimented male blossoms were present, and he attempts to exclude the operation of the pollen in these hermaphrodite flowers by suggesting that the anthers had only been opened for a very short time.
Bernhardi's experiments with Cannabis are given in "Otto u. Dietrich's Allgemeine Gartenzeitung, 1839." These experiments were continued for six years, and each year with the same result. 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.
Gartner's observations on Delphinium Consolida are important as showing the great care which must be taken in order to guard against deception. For some years he had taken what he considered sufficient precautions, and nevertheless had always obtained perfect seeds, apparently without any previous impregnation; but in the year 1838, when he cut off the male organs at an earlier period, and examined the plants several times daily, removing individual anthers at each examination, he found that the plants upon which he experimented produced no seeds.
We now come to the case of Cœlebogyne ilicifolia, the famous Euphorbiaceous plant, the great stumbling block of the opponents of parthenogenesis. This plant is dioecious, and the female one forms a low evergreen shrub, with pale green oval leaves, toothed like the holly. The female flowers are situated at the apex and on the side of small branches, and form short spikes of five or more flowers. The ovary is trilocular, and the stigma three-lobed. Each flower has on its calyx and bracts large wart-like glands, which at the time of flowering secrete a watery fluid. Three female plants were sent by Cunningham from Moreton Bay to Kew, where they flowered for the
