Lessons in elementary botany for secondary schools; . Fig. 6. Cross-section of a bundle of the Pumpkin-stem, diagram. a. Cortical portion (repeated below), b. The wood with large vessels. c. The cambium layer. An open bundle. bark portion of the bundle. Between these two parts, —bark and wood,— in favorable specimens the cambiumcan be seen as a white band passing across the sometimes shows better in thin slices cut with arazor, held toward the light, and examined with a a microscope of moderate power the structurecomes out perfectly, and at least one section should beexa
Lessons in elementary botany for secondary schools; . Fig. 6. Cross-section of a bundle of the Pumpkin-stem, diagram. a. Cortical portion (repeated below), b. The wood with large vessels. c. The cambium layer. An open bundle. bark portion of the bundle. Between these two parts, —bark and wood,— in favorable specimens the cambiumcan be seen as a white band passing across the sometimes shows better in thin slices cut with arazor, held toward the light, and examined with a a microscope of moderate power the structurecomes out perfectly, and at least one section should beexamined at this juncture in this way. Such a bundle 18 ELEMENTARY BOTANY. as this where the cambium persists is called an openbundle. We shall see the effect of this presently. II. The Cornstalk. Cut a thin section of the cornstalk hardened inalcohol, hold to the light, and note : — a. The beautiful lace-work formed by the cells ofthe -\--6 Fig. 7. Cross-section of the Cornstalk bundle, diagram. a. Cortical portion, poorly developed, b. One of the large vessels of the wood. No cambium ; a closed bundle. b. The bundles, rather small, but showing: — (1) Large vessels forming the woody part, as in the Pumpkin-vine section; and (2) A much smaller part, destitute of large vessels, the cortical portion of the bundle. There isno cambium. STEMS; THEIR STRUCTURE. 19 c. Put a section under the microscope, and the ab-sence of cambium will be very apparent. Such a bundleas this of the cornstalk is called a closed bundle. (SeeFig. 7.) III. The Tree Twig. Take a Willow twig about \ inch in diameter. Cutthe end smoothly across with a sharp knife or razor, andnote: — a. The white pith, rather small, proportionately, inamount. b. The wood, a cylinder quite well developed. Inthe section the medullary rays are seen as slender linesradiating in all directions from the pith. c. The bark, separate from the wood by a fairly plainline
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Keywords: ., bookcentury1800, bookdecade1890, booksubjectbotany, bookyear1896
