A laboratory course in plant physiology, especially as a basis for ecology; . , a method must be used by whichloss of water from leaves of an uninjured plant may be exactly cal-culated. For this a potted plant is convenient, but, obviously, evap-oration from the soil and pot must be prevented. Take a Ricinus 78 PLANT PHYSIOLOGY. or other leafy plant, and a glass jar just large enough to hold thepot ; cut a small hole in the center of a piece of rubber cloth whichis somewhat larger than needful to cover the top of the jar; slip therubber up over the pot and tie to the stem by a stretched rubber
A laboratory course in plant physiology, especially as a basis for ecology; . , a method must be used by whichloss of water from leaves of an uninjured plant may be exactly cal-culated. For this a potted plant is convenient, but, obviously, evap-oration from the soil and pot must be prevented. Take a Ricinus 78 PLANT PHYSIOLOGY. or other leafy plant, and a glass jar just large enough to hold thepot ; cut a small hole in the center of a piece of rubber cloth whichis somewhat larger than needful to cover the top of the jar; slip therubber up over the pot and tie to the stem by a stretched rubberband, and fasten the cloth over the top of the jar by a tight wire (seeFig. 14, plant in the center.) Insert a short thistle-tube through atiny hole. Make sure that the pot is enclosed water-tight. Weighon the spring-balance three times daily, as near sunrise as possible,at midday, and at sunset, and water once daily through the thistle-tube with an amount about equal to that given off. Keep a recordof temperature, moisture, and sunshine, and plot all four FIG. 14.—PREPARATION OF PLANTS FUR STUDY OF TRANSPIRATION. ()ne-fourth the true size. (In using the spring-balance, the weight must always be placed ex-actly in the center?) Another method of preventing evaporation from the pot is to wrap itcompletely in rubber cloth, gathered up and tied about the stem of theplant as shown in Fig. 14 on the left. The use of the glass, however,has three advantages : it allows the condition of the soil to be seen, thus TRANSPIRATION. 79 giving guidance to the watering, it allows a somewhat freer access ofoxygen to the roots, and it makes possible the experiments describedunder Experiment 21. Another method which has advantages is shownin Fig. 14 on the right, where the plant is removed from the pot andplaced in a battery-jar with enough extra earth to fill the latter ; the jaris then covered with the rubber precisely as described in the aboveexperiment. In this case the pla
Size: 1778px × 1405px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., boo, bookcentury1900, bookcollection, bookdecade1900, bookyear1901
