Elements of physiology : in two parts / by G. Hamilton.

  • Hamilton, George, 1808-1885
Date:
1849
Catalogue details

Licence: Public Domain Mark

Credit: Elements of physiology : in two parts / by G. Hamilton. Source: Wellcome Collection.

Provider: This material has been provided by the National Library of Medicine (U.S.), through the Medical Heritage Library. The original may be consulted at the National Library of Medicine (U.S.)

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    thus found to improve the air by the removal of carbonic acid, which is injurious to animal life, and by the restora- tion of oxygen, which is favourable to it; and so to maintain a necessary equilibrium in the atmosphere, as animals are continually absorbing oxygen, and giving out carbonic acid. In hot swampy countries, however, where vegetation is extremely rapid, and the soil surcharged with decaying vegetable matter, plants absorb more carbonic acid than they want, and give out the superfluity through their leaves; and hence, warm moist climates, such as those of some of the West India islands, though extremely favourable to vege- tation, are equally injurious to human life. 10. Light being essential to the decomposition of car- bonic acid gas in the leaves, oxygen is not exhaled by plants during the night; but, on the contrary, a small quantity of carbonic acid gas escapes, and oxygen is absorbed. These processes have been called the respiration of plants; but they are very different from the respiration of animals, the first being mechanical, and the second chemical, and both totally unconnected with the assimilation of food. When the soil abounds in carbonic acid gas and in moisture, the roots of a plant must continue constantly absorbing that moisture mixed with the carbonic acid; and this carbonic acid rising to the leaves, escapes in its original state when there is no light to decompose it. The absorption of oxy- gen is a chemical process, which appears to go on whenever the process of assimilation has ceased—in dead plants as well as in living ones. When leaves have ceased to act in decomposing carbonic acid, and assimilating or fixing the carbon in autumn, oxygen is absorbed so rapidly as to change their colour to some shade of red ; fruit, when fully swelled, ceases to assimilate carbon, and becomes intensely acid by the absorption of oxygen ; and, finally, the decay 13. What improvement of the air results from the leaves of plants T 14. What of hot swampy countries T 15. How are plants affected by the presence or absence of light? 16. Describe the mechanical and chemical process, which has been called the respiration of plants. 17. What occasions the red colour of leaves in autumn T 18. What hastens the decay of vegetable matter t
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