. Practical text-book of plant physiology. Plant physiology. 18 RELATIONS OF PLANTS TO MECHANICAL FORCES 25. Summation of Impulses. Secure a few good specimens of Dionaea growing in pots at a temperature of 25 to 300 C. Observe the mechanism of the curiously formed leaves. Objects roughly placed on the upper surfaces of the lobes cause them to fold up together applying the inner (upper) sides together. Now carefully touch one of the strong hair-like bodies growing up from each lobe of a plant hitherto undisturbed. If a firm gentle blow be given with a thin splinter of wood in such manner that
. Practical text-book of plant physiology. Plant physiology. 18 RELATIONS OF PLANTS TO MECHANICAL FORCES 25. Summation of Impulses. Secure a few good specimens of Dionaea growing in pots at a temperature of 25 to 300 C. Observe the mechanism of the curiously formed leaves. Objects roughly placed on the upper surfaces of the lobes cause them to fold up together applying the inner (upper) sides together. Now carefully touch one of the strong hair-like bodies growing up from each lobe of a plant hitherto undisturbed. If a firm gentle blow be given with a thin splinter of wood in such manner that but one. FlG. 5. Dionaea mttscipula. I, open normal leaf. 2, closed. 3, irritable spines (X 5°)- 4> glands on surface of leaf (X 100). After Green. shock is given to the hair no movement will follow. Repeat the blow on the same hair or any hair of the leaf within ten or fifteen seconds and the characteristic closure of the lamina will result. Give the blows with an interval of thirty seconds between and note result. Give a succession of very light blows separated by twenty-five to forty seconds. How many are necessary to secure movement P1 1 Dean, B. Dionaea. Its life habits and conditions. Trans. N. Y. Acad Sci. 12:9. 1892. See also, MacFarlane, J. M. Contributions to the history of Dionaea muscipula, Ellis. Cont. Bot. Lab. Univ. Penn. 1: 7. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original MacDougal, Daniel Trembly, 1865-1958. New York [etc. ] Longmans, Green, and Co.
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