Volume 3
A report on the progress of vegetable physiology during the year 1837 ... / Translated from the German by William Francis.
- Franz Meyen
- Date:
- 1839
Licence: Public Domain Mark
Credit: A report on the progress of vegetable physiology during the year 1837 ... / Translated from the German by William Francis. Source: Wellcome Collection.
128/172 page 120
![the affinity which exists between Lycopodium and Isoétes ; and since in Jsoétes the sporangia do not stand isolated in the axis of the leaf but upon it; since further in Psi/otum, and more evidently in Tmesipteris, the sporangium is situated on the leaf,—it becomes probable that the axillary position of the spo- rangia in Lycopodium also is merely apparent, and that they are rather a product of the leaf than of the stem. Yet these statements are merely ventured as suppositions, for M. Mohl found that the base of the sporangium is connected with the midrib of the leaf, in whose axis it is situated, as well as with the stem, so that we remain in doubt respecting its true point of insertion. Moreover the sporangium of Lycopodium may be much better compared to that of Botrychium, both in re- ference to the form and to the mode of bursting than to the carpel of phanogamous plants. After these researches, the question should be asked: whether the sporangia of the higher Cryptogamia can be re- garded as the same organ as the anthers in Phanerogamia, and the spores as the same organ as the pollen grains. This View was already advanced for various Cryptogamia by the in- genious Agardh, and founded indeed on the mode of germina-~ tion of the sporidia, in which a similar process was supposed to be recognized as at the formation of the pollen tube. M. Mohl has already previously contested this view, but thought that the growth of the pollen tube was a mere mechanical act produced by the endosmosis and the peculiar structure of the pollen grain. These tubes were said to be projected both in pollen grains, which had been dried for years, and in fresh ones, when moistened by acids and alcohol,—statements which were adopted by almost all botanists, but the incorrectness of which I demonstrated ten years ago, and at the same time proved, against M. Brongniart’s view, that the pollen tube did not arise from a mere expansion of the inner membrane of the pollen, but from actual growth. An elaborate and highly important memoir by Dr. Schleiden* is closely connected with the preceding one ; the author com- mences with the admonition that the doctrine of the metamor- * Einige Blicke auf die Entwickelungs- Geschichte des vegetabilischen Organismus bei den Phanerogamen.—Wiegmann’s Archiv. An English translation of the entire memoir appeared in the February and March Num- bers of the London and Edinburgh Philosophical Magazine.—W. F.]](https://iiif.wellcomecollection.org/image/b33490065_0003_0128.jp2/full/800%2C/0/default.jpg)
