On the action of light upon plants, and of plants upon the atmosphere

• Published in: Abstracts of the Papers Printed in the Philosophical Transactions of the Royal Society of London
• Format: Article in Journal/Newspaper
• Language: English
• Published: The Royal Society 1837
• Subjects: Carbonic acid
• Online Access: http://dx.doi.org/10.1098/rspl.1830.0225; https://royalsocietypublishing.org/doi/pdf/10.1098/rspl.1830.0225

The objects of the experimental inquiries of which the author gives an account in this paper were, in the first place, to ascertain the extent of the influence of solar light in causing the leaves of plants to emit oxygen gas, and to decompose carbonic acid, when the plants were either immersed in water, or surrounded by atmospheric air. The plants subjected to the former mode of trial were Brassica oleracea, Salicornia herbacea, Fucus digitatus, Tussilago hybrida, Co-chlearia armorica, Mentha viridis, Rheum rhaponticum, Allium ursinum , and several species of Gramineæ . Geraniums were the only plants subjected to experiment while surrounded with atmospheric air. Comparative trials were made of the action on these plants of various kinds of coloured light, transmitted through tinted glass, of which the relative calorific, illuminating, and chemical powers had been previously ascertained; and the results of all the experiments are recorded in tables; but no general conclusion is deduced from them by the author. He next describes a few experiments which he made on beans, with a view to ascertain the influence of light on the secretion of the green matter of the leaves, or rather to determine whether the change of colour in the chromule is to be ascribed to this agent. The third object of his inquiries was the source of the irritability of the Mimosa pudica , from which it appeared that light of a certain intensity is necessary for the maintenance of the healthy functions of this plant, and that when subjected to the action of the less luminous rays, notwithstanding their chemical influence, the plant lost its irritability quite as soon as when light was altogether excluded. He then examines the action of light in causing exhalation of moisture from the leaves; selecting Dahlias, Helianthuses, Tree Mallows, &c., as the subjects of experiment. The general tendency of the results obtained in this series is to show that the exhalation is, cæteris paribus , most abundant in proportion to the intensity of the light ...