Page:Natural History Review (1861).djvu/463

Rh previous influence of pollen, and consequently a true parthenogenesis exists."

Further on, Dr. Braun alludes to the fact of the persistence of the stigma (upon which, as wo have mentioned, Radlkofer relies) showing the absence of impregnation. In Cryptogams a remarkable instance of apparent parthenogenesis occurs in Chara crinita. In all the Characeæ, with the exception of this species, the male and female organs are equally common, sometimes on the same, sometimes on separate plants. After noticing the distinctive features of the species, its geographical distribution, and the certainty that in many localities the female plant alone exists, Dr. Braun gives it as his opinion that, at least in certain places, Chara crinita has the capacity of producing, without the operation of any male organ, normal spores capable of germination, and consequently that it affords an instance of veritable parthenogenesis.

In 'Bonplandia,' for 1857 (p. 209), Klotzsch suggested that the so-called embryo in Cœlebogyne is in fact not an embryo at all. He says that all the Euphorbiaceæ, without exception, have anatropal ovules, and a highly developed straight embryo with the radicle turned to the micropyle, whilst the large flat cotyledons winch enclose the plumule are directed to the chalaza. In Cœlebogyne, on the contrary, no freely developed embryo is perceptible, nor is there any trace of a radicle turned towards the micropyle, or of cotyledons turned towards the chalaza, Instead of the above, there is found an elliptical body within a fleshy, not albuminous, envelope, and consisting of a convoluted leaf-like mass, firmly attached on the inside of the seed to the chalaza by a discoid foot. From these facts Klotzsch arrives at the conclusion that the supposed embryo is a bud formed within the seed.

Ruprecht has objected that Klotzsch has given no figure of the perfect seed, and without this he seems to consider Klotzsch's observations open to doubt, at the same time expressing no opinion either for or against parthenogenesis.

Radlkofer's second essay on parthenogenesis relates to some matters of opinion in dispute between himself and Braun. He discusses the nature of the germinal vesicle before impregnation, and considers that in that stage it must be looked upon, not as the germ of the future plant, but as a rudimentary body capable of becoming a germ; a distinction somewhat subtle, and not very easily appreciable. He also enters upon the question of the analogy between the embryo-sac and the spore of the higher cryptogams. These matters, however, have no bearing upon the practical question as to the existence or non-existence of parthenogenesis in vegetables, and we refrain therefore from any further details with regard to them.

In 1859, Hegel's paper, "Die Parthenogenesis im pflanzen-reiche,"