§ IV.—Fermentation of Dextro-Tartrate of Lime.[135] Tartrate of lime, in spite of its insolubility in water, is capable of complete fermentation in a mineral medium. If we put some pure tartrate of lime, in the form of a granulated, crystalline powder, into pure water, together with some sulphate of ammonia and phosphates of potassium and magnesium, in very small proportions, a spontaneous fermentation will take place in the deposit in the course of a few days, although no germs of ferment have been added. A living, organized ferment, of the vibrionic type, filiform, with tortuous motions, and often of immense length, forms spontaneously by the development of some germs derived in some way from the inevitable particles of dust floating in the air or resting on the surface of the vessels or materials which we employ. The germs of the vibrios concerned in putrefaction are diffused around us on every side, and, in all probability, it is one or more of these germs that develop in the medium in question. In this way they effect the decomposition of the tartrate, from which they must necessarily obtain the carbon of their food, without which they cannot exist, while the nitrogen is furnished by the ammonia of the ammoniacal salt, the mineral principles by the phosphate of potassium and magnesium, and the sulphur by the sulphate of ammonia. How strange to see organization, life, and motion originating under such conditions! Stranger still to think that this organization, life, and motion are effected without the participation of free oxygen. Once the germ gets a primary impulse on its living career by access of oxygen, it goes on reproducing indefinitely, absolutely without atmospheric air. Here then we have a fact which it is important to establish beyond the possibility of doubt, that we may prove that yeast is not the only organized ferment able to live and multiply when out of the influence of free oxygen. Into a flask, like that represented in Fig. 67, of 2·5 litres (about four pints) in capacity, we put:— Pure, crystallized, neutral tartrate of 100 grammes. lime Phosphate of ammonia 1 gramme. Phosphate of magnesium 1 gramme. Phosphate of potassium 0·5 gramme. Sulphate of ammonia 0·5 gramme. (1 gramme=15·43 grains.) To this we added pure distilled water, so as to entirely fill the flask.