Subjoined is a table from the same work of the percentage of mineral substances taken up from the soil by various plants: ---------------------------------------------------------------------------------------------------------------- Substances Acids Oxide of Which -------------------------------- Iron, Charcoal, Yield Ammonia moisture, Ashes. Carbonic. Sulphuric. Phosphoric. Chlorine. Lime. Magnesia. Potash. Soda. Silica. etc. and loss. ---------------------------------------------------------------------------------------------------------------- Potatoes 13.4 7.1 11.3 2.7 1.8 5.4 51.5 traces 5.6 0.5 0.7 Mangel- Wurzel 16.1 1.6 6.1 5.2 7.0 4.4 39.0 6.0 8.0 2.5 4.2 Turnips 14.0 10.9 6.0 2.9 10.9 4.3 39.7 4.1 6.4 1.2 5.5 Potato Tops 11.0 2.2 10.8 1.6 2.3 1.8 44.5 traces 13.0 5.2 7.6 Wheat 0.0 1.0 47.0 traces 2.9 15.9 29.5 traces 1.3 0.0 2.4 Wheat Straw 0.0 1.0 3.1 0.5 8.5 5.0 9.2 0.3 67.6 1.0 3.7 Oats 1.7 1.0 14.9 0.5 3.7 7.7 12.9 0.0 53.3 1.3 3.0 Oat Straw 3.2 4.1 3.0 4.7 8.3 2.8 24.5 4.4 40.0 2.1 2.9 Clover 25.0 2.5 6.3 2.6 24.6 6.3 26.6 0.5 5.3 0.3 0.0 Pease 0.5 6.7 30.1 1.1 10.1 11.9 35.3 2.5 1.5 traces 2.3 French Beans 3.3 1.3 26.8 0.1 5.8 11.5 49.1 0.0 1.0 traces 1.1 Horse Beans 1.0 1.6 34.2 0.7 5.1 8.6 45.2 0.0 0.5 traces 3.1 ---------------------------------------------------------------------------------------------------------------- CHAPTER XIX. THE ELIMINATION OF WASTE SUBSTANCES. The expenditures of the human body, or the waste products which arise from the activity of the master tissues, are thrown off by the excretory tissues, as the lungs, the skin, the kidneys, and the terminal part of the intestines. The lungs are hollow organs, and we may consider them as really two bags containing air, each of which communicates by a separate orifice with a common air tube, through the upper part of which, the larynx, they freely communicate with the external atmosphere. The orifice of the larynx is guarded by muscles, and can be opened or closed at will.