. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. THE LEAF 177 Practical Questions 1. Can a plant be suffocated, and if so, in what ways? (87, 193; Exps. 26, 27.) 2. The roots on the palm shown in plate 3 are not drawing any sap from it as parasites; why does their continued growth bring about the death of the tree ? (87, 193.) 3. Is it unwholesome to keep flowering plants in a bedroom ? Leafy ones? Why, in each case? (191.) 4. Would there be any more reason for objecting to the presence of flowers by night than by day ?
. A practical course in botany, with especial reference to its bearings on agriculture, economics, and sanitation. Botany. THE LEAF 177 Practical Questions 1. Can a plant be suffocated, and if so, in what ways? (87, 193; Exps. 26, 27.) 2. The roots on the palm shown in plate 3 are not drawing any sap from it as parasites; why does their continued growth bring about the death of the tree ? (87, 193.) 3. Is it unwholesome to keep flowering plants in a bedroom ? Leafy ones? Why, in each case? (191.) 4. Would there be any more reason for objecting to the presence of flowers by night than by day ? Explain. (191.) 5. Why is respiration much less marked in plants than in animals? (30, 31.) VII. THE ADJUSTMENT OF LEAVES TO EXTERNAL RELATIONS Material. — A potted plant of oxalis, spotted medick, white clover, or other sensitive species. The subject is better suited for outdoor ob- servation than for laboratory work. Experiment 74. To show that leaves adjust themselves to changes in intensity op light. — Keep a healthy potted plant of oxalis, white clover, or spotted medick in your room for observation. Note the daily changes of position the leaves undergo. Sketch one as it appears at night and in the morning. In order to determine whether these changes are due to want of light or of warmth, put your plant in a dark closet in the middle of the day, with- out change of temperature. After several hours note results. Transfer to a refrigerator, or in winter place outside a window where it will be ex- posed to a temperature of about 5° C. (40° F.) for several hours, and see if any change takes place. Next put it at night in a well-lighted room and note the effect. If practicable, keep a specimen for several weeks in some place where electric lights are burning continuously all night, and watch the results. Experiment 75. To show that the pall op the leap mat result from other causes than cold or frost. — Wrap some leaves of ailan- thus, Kentucky coffee tree, ash, walnut,
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