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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    these cells are formed in the same way as those of plants. If this law is found essential to some plants and animals, this analogy forms a basis for enunciating this mode of formation as a universal law for both kingdoms of nature. In the same work Schwann has given an interesting comparison be- tween the formation of crystals and cells, and he was led to this from a consideration of the nature of the substances of which the last are formed. This view in future may be of the greatest importance, as it shows that the apparent gulph between the organic and inorganic kingdoms may not be impassable. There is one point to which I would allude, and which seems to have escaped the attention of Schwann. In the formation of the crystal, the matter of the same already exists, as such, dissolved in the fluid, and only awaits the withdrawal of the solvent to assume its peculiar form : it is otherwise in the cell of the plant. Here the organic substance forming the substance of the cell is not present in the cytoblast, but is formed through another necessarily present substance, and this only takes place when the new-formed substance is relatively insoluble. In the crystallisation of salts, such as the nitrate of potassa, from a solution, we can observe the increase of the crystal from additions to it from without. But, on the other hand, if we take a solution of two sub- stances which form, when mixed, a precipitate, we shall find, on examining this under the microscope, that a membrane divides the two fluids. Ac- curate observation will show that this membrane consists of crystals of various sizes. If the fluid remains quiet, some of the crystals are projected into it on both sides ; if the fluids are mixed, the crystals are dissolved up again. After many careful observations, I believe that all inorganic sub- stances, if they are allowed to remain quiet, assume a crystalline form; and that the so-called pulverulent precipitates consist of crystals, the form of which, from their smallness, cannot be observed. In the last place I must mention a highly interesting analogy, which, when more accurately examined, may perhaps one day lead to the most satisfactory explanation of the process of cell-formation, — I mean vinous fermentation. We have here a fluid in which sugar and dextrin, and a nitrogenous matter, as a cytoblast, are present. At a certain temperature, which is perhaps necessary to the chemical activity of the mucus, there originates, without, as it appears, the influence of a living plant, a process of cell-formation (the origin of the so-called fermentation-fungus), and it appears that it is only the vegetation of these cells which produces the peculiar changes that occur in the fluid. Whether this organism is really a fungus, is a matter of indifference; but whether it alone, through the activity of its vital processes, determines the process of fermentation, deserves to be accurately determined. I will here add my own observations on these fermentation-cells. I bruised some currants with sugar, and, having pressed the juice through a cloth, diluted it with water and filtered through folded paper. The fluid was bright red, quite clear and transparent, and, under the microscope, showed no trace of granules, but presented a number of little drops of a pure clear oil. At the end of twenty-four hours the whole fluid was opalescent, and presented, under the microscope, a number of granules suspended in it (fig. 9. a, Plate I.). On the second day these granules had greatly increased, and there appeared amongst them perfectly-formed ferment-cells (Plate I. fig. 9. a, b, c). There also appeared, now and then, fibres (Ilenlc, General Anatomy), have no analogues in plants. [Schwann’s treatise has been translated and published by the Sydenham Society. — Trans.]