. A civic biology : presented in problems. Biology; Sanitation. SOIL AND ITS RELATION TO ROOTS 77 by this process of osmosis is sufficient to send water up the stem to a distance, in some plants, of 25 to 30 feet. Cases are on record of water having been raised in the birch a distance of 85 feet. Physiological Importance of Osmosis. - - It is not an exaggera- tion to say that osmosis is a process not only of great importance to a plant, but to an animal as well. Foods are digested in the food tube of an animal; -that is, they are changed into a soluble form so that they may pass through the wa
. A civic biology : presented in problems. Biology; Sanitation. SOIL AND ITS RELATION TO ROOTS 77 by this process of osmosis is sufficient to send water up the stem to a distance, in some plants, of 25 to 30 feet. Cases are on record of water having been raised in the birch a distance of 85 feet. Physiological Importance of Osmosis. - - It is not an exaggera- tion to say that osmosis is a process not only of great importance to a plant, but to an animal as well. Foods are digested in the food tube of an animal; -that is, they are changed into a soluble form so that they may pass through the walls of the food tube and become part of the blood. The inner lining of part of the food tube is thrown into millions of little fingerlike projections which look somewhat, in size at least, like root hairs. These fingerlike processes are (unlike a root hair) made up of many cells. But they serve the same purpose as the root hairs, for they absorb liquid food into the blood. This process of absorption is largely by osmosis. Without the process of osmosis we should be unable to use much of the food we eat. Composition of Soil. - - If we examine a mass of ordinary loam carefully, we find that it is composed of numerous particles of vary- ing size and weight. Between these particles, if the soil is not caked and hard packed, we can find tiny spaces. In well-tilled soil these spaces are constantly be- ing formed and enlarged. They allow air and water to penetrate the soil. If we examine soil under the microscope, we find con- siderable water clinging to the soil particles and form- ing a delicate film around each particle. In this manner most of the water IS hekl in the SOU. Inorganic soil is being formed by weathering. How Water is held in Soil. - To understand what comes in with the soil water, it will be necessary to find out a little more about soil. Scientists who have made the subject of the composition of the earth a study,. Please note that these images are extracted from sca
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