"4. The form of these artificial pseudo-organic products is constant, as constant as that of the crystalline forms of mineral salts. This form is so characteristic that it may often serve for the recognition of a minimal proportion of a substance in a mixture. The observation of these forms is a means of analysis as sensitive as that of the spectrum. We may, for example, differentiate in this way the alkaline bicarbonates from the sesqui-carbonates or the carbonates.
"5. The form of these artificial pseudo-organic elements depends principally on the nature of the acid radical of the solid salt. Thus the sulphates and the phosphates generally produce tubes, while the carbonates form cells.
"6. As a rule these pseudo-organic forms are engendered only by substances which are found in the living organism. Thus sucrate of calcium will engender organic forms, whereas sucrate of strontium or barium does not do so. There are, however, some exceptions to this rule, such as the sulphates of copper, cadmium, zinc, and nickel.
"7. These artificial pseudo-organic elements are surrounded by veritable membranes, dializing membranes which allow only liquids to pass through them. These artificial cells have heterogeneous cell-contents, and produce in their interior granulations which are disposed in a regular order. Thus they are both in constitution and in form absolutely similar to the cellular elements which constitute living organisms.
"8. It is probable that the inorganic elements which are present in the natural protoplasm may play an important part
in determining the form which is assumed by the figured elements of the organism."
In 1902, Professor Quinke of Heidelberg, who has consecrated his life with such distinction to the physics of liquids, writes thus of the organogenic power of liquids in a paper published in the Annalen der Physik under the title "Unsichtbare Flüssigkeitschichten": "In 1837, Gustav Rose obtained organic forms by precipitation from inorganic solutions. By precipitating chloride of calcium with the carbonates of ammonium and other alkaline carbonates, he obtained small spheres which grew and were transformed into calcic rhombohedra. He also obtained a flocculent precipitate which later became granular and showed under the microscope forms like the starfish, and discs with undulated borders. At Freiberg, in certain stalactites, Rose also discovered forms consisting of six pyramidal cells around a spherical nucleus.
"In 1839, Link obtained spherical granulations by the precipitation of calcic or plumbic solutions by potash, soda, or carbonic acid. These spherical granulations united after a time to form crystals. Sulphate of iron, ammoniated sulphate of zinc, sulphate of copper precipitated by sulphuretted hydrogen, and saline solutions precipitated by ferrocyanide of potash, all give granular precipitates or discs, of which the granular origin is quite perceptible.
"Runge in 1855 was the first to describe the formation of periodic chemical precipitates. He used blotting paper as the medium in which various chemical substances met by diffusion. In this way he studied the mutual reactions of solutions of ferrocyanide of potash, chloride of iron, and the sulphates of copper, iron, manganese, and zinc. The coloured precipitates appeared at different positions in the paper, and disappeared periodically at greater or longer intervals. The designs formed by these coloured precipitates change with the concentration of the saline solutions, or on the addition of oxalic acid, salts of potash or ammonia, and other substances. These designs are shown in a number of beautiful illustrations which accompany the work. In this
case the capillarity of the paper necessarily exerts a certain influence on the formation of the figures, but in addition to this, Runge admits the intervention of another force hitherto unknown, which he calls 'Bildungstrieb,' the formative impulse, which he considers to be the elementary vital force in the formation of plants and animals.