The microscope : and its application to vegetable anatomy and physiology / by Dr. Hermann Schacht ; edited by Frederick Currey, M. A.

  • Hermann Schacht
Date:
1855
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Licence: Public Domain Mark

Credit: The microscope : and its application to vegetable anatomy and physiology / by Dr. Hermann Schacht ; edited by Frederick Currey, M. A. Source: Wellcome Collection.

    166/230 (page 142)
    out of one or more oiiginally sepai'ate leaves. The number of these parts seldom stands in any dehnite relation to the parts of tiie })receding whorl. In very many cases it will be a matter ot doubt whether the ovaiy is formed from the stem or from leaves. The inferior ovary must always proceed fi-om the stem, inasmuch as it bears the whorls above it. 7. The origin of the placentje and ovules, and the nucleus, coatings, and embryo-sacs of the latter. This investigation is of great ini})ortance; it shows whether the dissejiinients of the ovaiy are true or false. In CEiiothera, Clarkia, Epilobium, in the Cucurbitaceie, in Pyrola, Monotropa, <fcc., they are false;'and ai‘C in fact, foianed out of the ]>arietal placentai. True dissej)i- ments, on the other hand, originate from the foldmg inwards and growing together of the edges of at least two carpellary leaves, tis is the case in Papaveracea? and Nymplueaceoe. False dissepi- ments ai'e much the most common. Transverse sections of the stigma and style will seldom aflbrd satisfactory information. In longitudinal sections the following points mu.st be attended to:— 1. The primary insertion of the parts of one or more of the whorls, and Avhether their position, at a later period of develo})e- ment, has remained unaltered; or whether the parts of one or other of the whorls are pushed upwards. The formation of a disc, the origin of appendicxdar organs, the developement of hairs, &c., must also be attended to. The cupule of the oak and the beech is developed from a disk, which, during the period of its formation, produces leaves under its edge; these leaves, in the oak, are of a scale-like nature. 2. The developement of the ovaiy. The apex of the origi- nal flower-bud may extend itself into the hollow of the ovary, and form a free axile placenta, as in the Primulacea’!, Lentilni- lariacese, etc.; or the apex may extend itself in like manner, but become united with the pre-existing parietal placenta^ and thus m:ike the lower part of the ovary multi-locular, whilst the upper part is uni-locular, and furnished with as many parietal placenta as there are loculi in the lower }>a.rt. It may happen also that the columella may become united with the introverted edges of