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.

    163/230 (page 139)
    times liable to be overlooked, and other difficulties frequently occur. Eveiy beginner, therefore, should be advised, before commencing the study of the developement of irregular dowel's, to make himself fully acquainted 'svith the develo})ement of re- gular dowers. The dowers of fEiiothera, Clarkia, and E})ilo- bium are well adapted for this purpose. In order to render the investigation more easy, it is necessary to select plants whicli have a spiked or clustered indorescence, and moreover plants which have but few bail's. The longitudinal section througli tlie middle of such a spike exhibits, simidtaneously in the axils of the bracts, different stages of the developement of the dower. Moreover, when the dowers have but few bail’s, the examination of them is much less liable to eiTor, since air is often collected between the hairs, and this must d.rst be removed with alcohol, the use of which, in such young specimens, is often not advisa- ble. In examining the developement of the dowers, two modes of ])roceeding may be adopted. First, the parts of the dower in their successive stages may be prepared separately by the aid of the simple microscope ; and, secondly, very delicate longitudinal and transverse sections, in certain dednite directions, may be made through the whole of the dower. The second mode of proceeding is decidedly preferable; it is more rapid and more certain in its results; it affords a far more acciu’ate insight into the internal condition of the dower and its parts; and lastly, ffiter a little practice, it is far more convenient and easily ma- naged. In preparing the separate parts, there is no security, notwithstanding the greatest dexterity in the use of the needle, against their being injiu'ed; and dually, the observations are rendered difficult by the fact that the parts of the dower must be ffiewed as bodies, by vai'ying the adjustment of the micro- scope, and cannot, as in the case of tlie sections, be examined as surfaces. In many cases, as for instance in examining the deve- lopeTiient of the dowers of gi’asses, both methods should be used. In selecting specimens for examination, the youngest dower- ing branches should be taken. The longitudinal sections should lie made Avith the rmassisted hand. The section must be very thin, and must exhibit accurately the middle lamella of the dowering branch; and in examining it, the terminal bud and