A laboratory course in plant physiology, especially as a basis for ecology; . showing: (a) Quantitatively and qualitatively the distribution ofChlorophyll in a complete higher plant, and (//) The structure of the most specialized green chlorophyll-bearing organ, and (c] The structure of a single green cell. PHO TOS YN THESIS. 51. Is light absolutely essential to Photosynthesis?Answer by Experiment 24. EXPKRIMKNT 24. This may be tested by placing similar leaves fora time under conditions precisely alike except that one is exposed tolight and the other kept in darkness, and then applying a test
A laboratory course in plant physiology, especially as a basis for ecology; . showing: (a) Quantitatively and qualitatively the distribution ofChlorophyll in a complete higher plant, and (//) The structure of the most specialized green chlorophyll-bearing organ, and (c] The structure of a single green cell. PHO TOS YN THESIS. 51. Is light absolutely essential to Photosynthesis?Answer by Experiment 24. EXPKRIMKNT 24. This may be tested by placing similar leaves fora time under conditions precisely alike except that one is exposed tolight and the other kept in darkness, and then applying a test forstarch. Place a Tropaeolum or other convenient thin-leaved plantfor two nights and a day in darkness (to empty it of starch); as earlyas convenient the next day bring it into light; cover one leaf com-pletely on both sides with tin-foil, leaving another beside it uncov-ered ; or, cover a leaf with tin-foil in which, matching above andbelow, some pattern has been cut (see Fig. 16), leaving the leaf thereexposed to light on both faces; or, by means of pins thrust through. FIG. 16.—ARRANGEMENTS FOR STUDY OF PHOTOSYNTHESIS. (Instead of the blackpaper cover on the left, tin-foil should be used.) One-third the true size. the leaf, place two pieces of cork on opposite sides of a leaf, match-ing above and below (see Fig. 16). Keep the plant all day inbright sunlight, and towards sunset place the leaves for a few min-utes in boiling water (to kill them and swell the starch), and placein 70.^ alcohol. Later, at a convenient time, warm the alcohol in awater-bath and renew it until all the green is removed, and the leavesare blanched. To bring out the starch distribution, place them in a 86 PLANT PHYSIOLOGY. porcelain or other white-bottomed dish, and pour over them aniodine solution (made by dissolving solid iodine in weak aqueoussolution of potassic iodide until the mixture has a dark wine color),which will turn all starch dark blue. (In warming the leaf in alcohol to blanch it more
Size: 1325px × 1886px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookcollection, bookdecade1900, bookyear1901
