Researches on the motion of the juices in the animal body : and the effect of evaporation in plants : together with an account of the origin of the potato disease, with full and ingenious directions for the protection and entire prevention of the potato plant against all diseases / by Justus Liebig ; edited from the manuscript of the author by William Gregory.
- Justus von Liebig
- Date:
- [1850?]
Licence: Public Domain Mark
Credit: Researches on the motion of the juices in the animal body : and the effect of evaporation in plants : together with an account of the origin of the potato disease, with full and ingenious directions for the protection and entire prevention of the potato plant against all diseases / by Justus Liebig ; edited from the manuscript of the author by William Gregory. 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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![INFLUENCE OF THE MEMBRANES ON THE SECRETIONS. 3] through the urinary passages. If we add to the water colored or odorous matters, these appear, more or less changed in the urine. When a small quantity of ferrooyanide of potassium is added, its presence in the urine is very soon detected by chloride of iron, which forms with it Prussian blue. Of concentrated solutions far less is absorbed in the same time, than of diluted; in most cases they mix with solid matters collected in the rectum, and are expelled in the form of a watery dejection. All salts do not act alike in this respect. In equal doses, the purgative action of Glauber salt and Epsom salt is far stronger than that of sea salt; and their power of being absorbed by animal membranes appears to be in the inverse ratio of this effect. It is hardly necessary, particularly to point out that an explanation of the action of purgatives in general cannot be included in the above-described action of saline solutions on the organism. The example which has been given is intended to illustrate a physical property common to a large number of salts, and apparently of the nature of the acid or base of the salt; for chloride of calcium, chloride of magnesium, bitartrate of potash, tartrate of potash and soda, phosphate of soda, and certain doses of tartar emetic, show the same action as sea salt, Glauber salt, and Epsom salt, although the bases and acids in these different salts are not the same. Solutions of cane sugar, grape sugar, sugar of milk, and gum, exhibit, when separated from water by an animal membrane, phenomena similar to those exhibited by the above-named solutions of mineral salts, without causing in the living body a purgative action, when of equal concentration. The cause of this difference may be that the mineral salts, in their passage through the intestinal canal, and through the blood, are not essentially altered in their composition, while these organic substances, in contact with the parietes of the stomach, and under the influence of the gastric juice, suffer a very rapid change, by which the action which they have out of the body is arrested. Since the chemical nature and the mechanical character of mebranes and skins exert the greatest influence on the distribution of the fluids in the animal body, the relations of each membrane presenting any peculiarity of structure, or of the different glands and systems of vessels, deserve to be investigated by careful experiment ;* and it might very likely be found that in the secretion of the milk, the bile, the urine, the sweat, &c, the membranes and cell-walls play a far more important part than we are inclined to ascribe to them; that besides their physical properties, they possess certain chemical properties, by which they are enabled to produce decompositions and combinations, true analyses ; and if this were ascer- tained, the influence of chemical agents, of remedies, and of poisons on those properties, would be at once explained. The phonomena described in the preceding pages are observed, not in the gelatinous tissues alone, but also, apparently, in many other structures of the animal body, which cannot be reckoned as belonging to that class.! If we tie moist paper over the open end of a cylindrical tube, and, after pouring in above the paper white of egg to the height of a few lines, place that end of the tube in boiling water, the albumen is coagulated, and when the paper is removed, we have a tube closed with an accurately fitting plug of coagulated albumen, which allows neither water nor brine to run through.^ If the tube be now filled to one-half with brine, and immersed in pure water, as in Fig. 4, the brine is seen gradually to rjse; and in three or four days it increases by from | to \ of its volume, exactly as if the tube had been closed with a very thick membrane. Influence of the cutaneous evaporation on the motion of the fluids of the animal body. When a tube about 30 inches long, bent in the form of a knee, and widened at one end, is tied over at that end with a piece of moist ox-bladder, the bladder now * Influence of membranes on secretions. t These phenomena not confined to the gelatinous tissues.](https://iiif.wellcomecollection.org/image/b21136944_0033.jp2/full/800%2C/0/default.jpg)
