Principles of scientific botany, or, Botany as an inductive science / by J.M. Schleiden ; translated by Edwin Lankester.

Date:
1849
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Licence: Public Domain Mark

Credit: Principles of scientific botany, or, Botany as an inductive science / by J.M. Schleiden ; translated by Edwin Lankester. Source: Wellcome Collection.

Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.

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    reverse, the alcohol readily passing through this substance. Similar modifications in the simplest processes of cell-life must take place, on account of the countless varieties of cell-membrane. In all experiments, however, it is necessary to avoid the the hypothesis of the porosity of the organic membrane, which can only be attended with the same bad results as the notion of the existence of atoms in chemistry.* § 32. The most universally distributed medium of solution in nature, water, is also the fluid which is absorbed by the plant- cell, and conveys all other matters into its interior. The most essential of these matters are carbonic acid and ammonia, both of which are contained in water which either falls from the air or has been a long time in contact with it. Water, carbonic acid, and ammonia contain carbon, hydrogen, oxygen, and nitrogen, all of which are essential to the formation of the assimilated substances and to the especial nourishment of the cell. But the water occa- sionally conveys to the cell, in small quantities, all substances which are capable of solution in water. In spite of the almost endless works upon the nourishment of plants, nothing is in a more uncertain state than our knowledge of the food necessary for plants. This has arisen from the facts having been selected from, and the experiments made upon, the higher and more complicated forms of plants instead of the lowest. The simplest and most natural object for such researches is the Protococcus viridis, or some other simple Conferva, which consists of one or only a few cells, and which floats free in water, and contains the substances universally necessary for the life of the cell. These plants require nothing more for their vegetation than pure water, which has taken up from the atmosphere carbonic acid and ammonia, and perhaps a very small quantity of inorganic salts; the necessity for which last has not been proved, but is supposed to be necessary from analogy with the higher plants. The experiment is easily made of supplying these plants with water containing a large quantity of carbonic acid, when they will be found to grow more rapidly, and thrive more luxuriously, than when placed in water to which humus, humic acid, or humic acid salts have been added. This is sufficient proof that these last substances are not essential to the life of the cell. It is worthy of remark, that just as Carices, and other so-called moor- plants, flourish with a certain quantity of humic acid, which is generally unfavourable to vegetation, so also other plants, as the little Conferva which requires tannin and grows in infusions of galls, require other substances. I he Mycoderma aceti grows under the influence of the decomposition of vinegar. In these cases, probably, the free acid is as little necessary to nutrition as in other plants, but the mode and manner o t ie decomposition of the acid is a favouring moment for the vegetation of the above-named plants. Im\ lesearches have been made on the nature of the nitrogenous su ^stances in the simplest plants. I have hitherto supposed that the nitiogenous compounds ol plants are pure protein. But if we regard * S-e,c fhitrocliet, L Agent lmmediat du Mouvement vita] devoile, See. Paris, 1826. Also Poggendorffs Anna en, vol. xi. p. 138., vol. xxviii. p. 134. ; and Schweigger’s Journal, Ivin. p. 1. 20. [Also Draper on the Chemistry of Plants, and Matteucci the Physical Phenomena of Living Beings. Trans.] on