CHAPTER VII.

MODIFIED CIRCUMNUTATION: NYCTITROPIC OR SLEEP MOVEMENTS OF LEAVES.

Conditions necessary for these movements--List of Genera and Families, which include sleeping plants--Description of the movements in the several Genera--Oxalis: leaflets folded at [page viii.] night--Averrhoa: rapid movements of the leaflets--Porlieria: leaflets close when plant kept very dry--Tropaeolum: leaves do not sleep unless well illuminated during day--Lupinus: various modes of sleeping--Melilotus: singular movements of terminal leaflet--Trifolium--Desmodium: rudimentary lateral leaflets, movements of, not developed on young plants, state of their pulvini--Cassia: complex movements of the leaflets--Bauhinia: leaves folded at night--Mimosa pudica: compounded movements of leaves, effect of darkness--Mimosa albida, reduced leaflets of--Schrankia: downward movement of the pinnae--Marsilea: the only cryptogam known to sleep--Concluding remarks and summary--Nyctitropism consists of modified circumnutation, regulated by the alternations of light and darkness--Shape of first true leaves...Page 317-417

CHAPTER VIII.

MODIFIED CIRCUMNUTATION: MOVEMENTS EXCITED BY LIGHT.

Distinction between heliotropism and the effects of light on the periodicity of the movements of leaves--Heliotropic movements of Beta, Solanum, Zea, and Avena--Heliotropic movements towards an obscure light in Apios, Brassica, Phalaris, Tropaeolum, and Cassia--Apheliotropic movements of tendrils of Bignonia--Of flower-peduncles of Cyclamen--Burying of the pods--Heliotropism and apheliotropism modified forms of circumnutation-- Steps by which one movement is converted into the other-- Transversal-heliotropismus or diaheliotropism influenced by epinasty, the weight of the part and apogeotropism--Apogeotropism overcome during the middle of the day by diaheliotropism--Effects of the weight of the blades of cotyledons--So called diurnal sleep--Chlorophyll injured by intense light--Movements to avoid intense light...418-448

CHAPTER IX.

SENSITIVENESS OF PLANTS TO LIGHT: ITS TRANSMITTED EFFECTS.

Uses of heliotropism--Insectivorous and climbing plants not heliotropic-- Same organ heliotropic at one age and not at another--Extraordinary sensitiveness of some plants to light--The effects [page ix.] of light do not correspond with its intensity--Effects of previous illumination--Time required for the action of light--After-effects of light--Apogeotropism acts as soon as light fails--Accuracy with which plants bend to the light--This dependent on the illumination of one whole side of the part--Localised sensitiveness to light and its transmitted effects--Cotyledons of Phalaris, manner of bending--Results of the exclusion of light from their tips--Effects transmitted beneath the surface of the ground--Lateral illumination of the tip determines the direction of the curvature of the base--Cotyledons of Avena, curvature of basal part due to the illumination of upper part--Similar results with the hypocotyls of Brassica and Beta--Radicles of Sinapis apheliotropic, due to the sensitiveness of their tips--Concluding remarks and summary of chapter-- Means by which circumnutation has been converted into heliotropism or apheliotropism...Page 449-492

CHAPTER X.

MODIFIED CIRCUMNUTATION: MOVEMENTS EXCITED BY GRAVITATION.

Means of observation--Apogeotropism--Cytisus--Verbena--Beta--Gradual conversion of the movement of circumnutation into apogeotropism in Rubus, Lilium, Phalaris, Avena, and Brassica--Apogeotropism retarded by heliotropism--Effected by the aid of joints or pulvini--Movements of flower-peduncles of Oxalis--General remarks on apogeotropism--Geotropism-- Movements of radicles--Burying of seed-capsules--Use of process--Trifolium subterraneum--Arachis--Amphicarpaea--Diageotropism--Conclusion...493-522

CHAPTER XI.

LOCALISED SENSITIVENESS TO GRAVITATION, AND ITS TRANSMITTED EFFECTS.

General considerations--Vicia faba, effects of amputating the tips of the radicles--Regeneration of the tips--Effects of a short exposure of the tips to geotropic action and their subsequent amputation--Effects of amputating the tips obliquely--Effects of cauterising the tips--Effects of grease on the tips--Pisum [page x.] sativum, tips of radicles cauterised transversely, and on their upper and lower sides--Phaseolus, cauterisation and grease on the tips--Gossypium-- Cucurbita, tips cauterised transversely, and on their upper and lower sides--Zea, tips cauterised--Concluding remarks and summary of chapter-- Advantages of the sensibility to geotropism being localised in the tips of the radicles...Page 523-545

CHAPTER XII.

SUMMARY AND CONCLUDING REMARKS.

Nature of the circumnutating movement--History of a germinating seed--The radicle first protrudes and circumnutates--Its tip highly sensitive-- Emergence of the hypocotyl or of the epicotyl from the ground under the form of an arch--Its circumnutation and that of the cotyledons--The seedling throws up a leaf-bearing stem--The circumnutation of all the parts or organs--Modified circumnutation--Epinasty and hyponasty--Movements of climbing plants--Nyctitropic movements--Movements excited by light and gravitation--Localised sensitiveness--Resemblance between the movements of plants and animals--The tip of the radicle acts like a brain...546-573

INDEX...574-593

The Power of Movement in Plants Page 03

19th Century English Literature

Charles Darwin

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Charles Darwin

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