. Handbook of nature-study for teachers and parents, based on the Cornell nature-study leaflets. Nature study. 728 Handbook of Nature-Study. TJie upturned roots of a while pine; a part of a stump fence a century old. To understand how firm a base the roots form to hold up the tall trunk, we need to see an uprooted tree. The great roots seem to be molded to take firm grasp upon the soil. It is interesting to study some of the "stump fences" which were made by our forefathers, who uprooted the white pines when the land was cleared of the primeval for- est, and made fences of their wide
. Handbook of nature-study for teachers and parents, based on the Cornell nature-study leaflets. Nature study. 728 Handbook of Nature-Study. TJie upturned roots of a while pine; a part of a stump fence a century old. To understand how firm a base the roots form to hold up the tall trunk, we need to see an uprooted tree. The great roots seem to be molded to take firm grasp upon the soil. It is interesting to study some of the "stump fences" which were made by our forefathers, who uprooted the white pines when the land was cleared of the primeval for- est, and made fences of their widespreading but rather shal- low extending roots. Many of these fences stand to-day with branching, out-reaching roots, white and weather-worn, but still staunch and massive as if in memory of their strong grasp upon the soil of the wilderness. The trunk, or bole, or stem of the tree has also two chief offices: It holds the branches aloft, rising to a sufficient height in the forest so that its head shall push through the leaf canopy and expose the leaves to the sun- light. It also is a channel by which the water containing the food surges from root to leaf and back again through each growing part. The branches are divisions of the trunk, and have the same work to do. In cross-section, the tree trunk shows on the outside the layer of protec- tive bark; next to this comes the cambium layer, which is the vital part of the trunk; it builds on its outside a layer of bark, and on its inside a layer of wood around the trunk. Just within the cambium layer is a lighter colored portion of the trunk, which is called the sap-wood because it is filled with sap which moves up and down its cells in a mysterious manner; the sap-wood consists of the more recent annual rings of growth. Within the sap-wood are concentric rings to the very center or pith; this portion is usually darker in color and is called the heartwood; it no longer has anything to do with the life of the tree, but simply gives
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