An elementary course of botany : structural, physiological and systematic / by Arthur Henfrey.

  • Arthur Henfrey
Date:
1870
Catalogue details

Licence: Public Domain Mark

Credit: An elementary course of botany : structural, physiological and systematic / by Arthur Henfrey. Source: Wellcome Collection.

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    INTRODUCTION. mentary organs may bo picked out with a needle or extremely fine camel-hair pencil, under a simple lens of ^- or ^-inch focus, and re- moved to a clean slide. The thin slices, or the fragments of macerated tissues, should be laid upon a slip of glass, a drop of water added, and a thin glass cover laid on. They may then be examined under the compound microscope. Objects of microscopic dimensions, such as minute Alga), Fungi, pollen-grains, &c., require no preparation. It is very instructive to apply chemical reagents of various kinds to the objects lying in water upon the microscopic slide. Dilute sulphuric acid is often useful to coagulate protoplasmic structures, and to clear delicate tissues; when this is added first, and afterwards solution of iodine, the younger cellular structures turn blue, while the older ones become deep yellow. Iodine alone colours starch- grains blue. Sugar and nitric acid colour the protoplasmic struc- tures red. These reagents may be applied by means of dropping from a glass rod or fine tube. It is often advantageous to soak the sections for some hours in a solution of pure carmine in ammonia diluted with water. The nuclei and cell-contents become tinged with the carmine, and can thus be more readily distinguished from the cell-wall. More particular reference will be made to them in the chapters on Anatomy. Microscopic preparations of soft vegetable structures are best preserved in glycerine or strong solution of chlo- ride of calcium. Some objects are advantageously mounted in Canada balsam ; these must be well dried first, and, for a few days previously to mounting, should be soaked in spirits of turpentine. Those who desire to obtain minute instructions on the manipula- tions necessary for the study of Vegetable Anatomy, may consult Schacht's ' Microscope,' translated by Currey, or the articles on these subjects in the ' Micrographic Dictionary.' In physiological investigation various pieces of philosophical appa- ratus are requisite. It will suffice to notice these when their appli- cations are mentioned.
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