. Essentials of botany. Botany; Botany. 16 ESSENTIALS OF BOTANY 19. Microscopical Examination of Starch.^ — Examine starch in water with a rather high power of the microscope (not less than 200 diameters). Pulp scraped from a potato, that from a canna rootstock, wheat flom-, the finely powdered starch sold under the commercial name of " cornstarch " for cooking, oatmeal, and buckwheat finely powdered in a mortar, will furnish excellent examples of the shape and mark- ings of starch grains. Sketch all of the kinds examined, taking pains to bring out the markings.^ Compare the sketches
. Essentials of botany. Botany; Botany. 16 ESSENTIALS OF BOTANY 19. Microscopical Examination of Starch.^ — Examine starch in water with a rather high power of the microscope (not less than 200 diameters). Pulp scraped from a potato, that from a canna rootstock, wheat flom-, the finely powdered starch sold under the commercial name of " cornstarch " for cooking, oatmeal, and buckwheat finely powdered in a mortar, will furnish excellent examples of the shape and mark- ings of starch grains. Sketch all of the kinds examined, taking pains to bring out the markings.^ Compare the sketches with Figs. 7 and 8. With a medicine-dropper or a very small pipette run a drop of iodine solu- tion under one edge of the cover-glass, at the same time withdrawing a little water from the margin opposite by touch- ing to it a bit of blotting paper. Exam- ine again and note the blue coloration of the starch grains and the unstained or yellow appearance of other substances in the field. Cut very thin slices from beans, peas, or kernels of corn; mount in water, stain as above directed, and draw as seen under the microscope. Compare with Figs. 7 and 8.' Note the fact that the starch is not packed away in the seeds in bulk, but that it is enclosed in little chambers or Fig. 7. Canna Starch. (Magnified 300 diameters.) 20. Plant-Cells. — Almost all the parts of the higher plants are built up of little separate portions called cells. The cell is the unit of plant-structure, and bears something i At this point the teacher should give a brief illustrated talk on the con- Btruction and theory of the compound microscope. 2 The markings will be seen more distinctly if care is taken not to admit too much light to the object. Rotate the diaphragm beneath the stage of the microscope, or otherwise regulate the supply of light, until the opening is found which gives the best effect. 8 The differentiation between the starch grains, the other cell-contents, and the cell-walls will app
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Keywords: ., bookcentury1900, bookdecade1900, booksubjectbotany, bookyear1908
