MICROSCOPIC PREPARATIONS. 617 



tions, it is proper to begin the examination of any structure with the lower 

 magnifying powers, and then to pass from them to the higher; and at all times 

 to prefer the lower power when possible. The light passing through the in- 

 strument should be moderate, and the eyes ought, as much as possible, to be 

 screened from external light; the instrument ought to be placed at such a 

 height, and in such a position, as will prevent either stooping in a constrained 

 attitude, or fatigue from long-continued observation. In acquiring proficiency 

 in the microscope, the student will find it easiest to begin with the various 

 forms of cells in Confervas and other simple cellular plants, and then to proceed 

 to the vascular tissues of higher plants, directing his attention first to the sec- 

 tions of the softer parts, and then to various kinds of woods. From this he may 

 pass on to the structure of the leaves, flowers, pollen, seeds, and spores, and to 

 the phenomena of fecundation, and the movement of fluids in plants.* 



MICROSCOPICAL PREPARATIONS. 



1201. The following is a list of some of the preparations used in the Botan- 

 ical Class at Edinburgh, for illustrating vegetable structures: 



Cellular Tissue. Section of pith of Elder, section of Rice-Paper plant, nu- 

 cleated cells in the Onion Bulb, in Jungermannia bidentata, stellate cells 

 of Juncus, hairs of Cotton. 



Cellular Plants. Conferva, Diatoma, Isthmia, Licmophora, Closterium, Ha- 

 matoco'ccus, Draparnaldia, Meloseira, Schizonema, Spluvroplea, Dickieia, 

 Rivularia, Spirulina, Ulva, Anabaina. 



Spiral Cells. Oncidium, Jungermannia, Episperm of Salvia, Collomia, 

 Acanthodium, Lophospermum, Cobrca, wing of the seed of Calempelis 

 scaber. 



Woody Fibre. Root of Elder, Flax, Hemp. 



Spiral Vessels. Canna bicolor, Nepenthes, Banana, Cactus, Hyacinth, As- 

 paragus, Balsam, branching spirals in Misletoe and Long-leek. 



Porous Vessels. Sugar-cane, Nepenthes. 



Annular Vessels. Root of Opuntia. 



Scalariform Vessels. Osmunda, Asplenium, Cheilanthes. 



Laticiferous Vessels. Ficus elastica, Euphorbia, Tragopogon, Chelidonium. 



Cuticle. Pelargonium, Oncidium, Wheat Straw, Equisetum. 



Glands and Scales. Leaf of Mentha, Aloysia, Elooagnus, Sweet Briar. 



Hairs. Cynoglossum, Sterculia, Goldfussia, Trichinium, Stifftia, Alyssum, 

 Tradescantia, Antirrhinum, Deutzia, Nettle, Chinese Primrose. 



Stomata. Hyacinth, Begonia, Oleander, Lilium, Equisetum. 



Starch. Arrow -root, Tous-les-mois, Potato. 



Raphides. Hyacinth, Rhubarb, Arum, Onion, Balsam, Cactus, Ficus. 



Vertical Section of Leaf . Oleander, Ficus. 



Leaf and Root- Appendages. Bladder of Utricularia, sheath of Lemna. 



Exogenous Stem and Root. Clematis, Chestnut, Alder, Poplar, Willow, 

 Eider, Birch, Bread-fruit Tree, Banksia, Bignonia, Drymis, Ebony, Fir, 

 Pepper, Cedar, Norfolk Island Pine, Savin, Oak, Elm. 



Endogenous Stem. Palm, Cane, Sugar-cane, Corypha. 



Acrogenous Stem. Tree-fern. 



* For full details as to the construction of microscopes and tlie mode of making preparations, 

 consult Quekett's " Practical Treatise on the use of the Microscope." London, IS- 



