How crops growA treatise on the chemical composition, structure, and life of the plant, for all students of agriculture .. . ter a time become so in-durated externally, that all lateral expansion ceases, andthe stem increases only in height. It grows, nevertheless,internally, new fibers developing in the softer portions,until, in some cases, the tree dies because its interior is soclosely packed with fibers that the formation of new ones,and the accompanying vital processes, become impossible. In herbaceous endogens the soft stem admits the indefi-nite groVrth of new vascular tissue. The stems
How crops growA treatise on the chemical composition, structure, and life of the plant, for all students of agriculture .. . ter a time become so in-durated externally, that all lateral expansion ceases, andthe stem increases only in height. It grows, nevertheless,internally, new fibers developing in the softer portions,until, in some cases, the tree dies because its interior is soclosely packed with fibers that the formation of new ones,and the accompanying vital processes, become impossible. In herbaceous endogens the soft stem admits the indefi-nite groVrth of new vascular tissue. The stems of the grasses are hoUow, except at thenodes. Those of the rushes have a central pith free fromvascular tissue. Tbc Minnte Stractnre of tbe Endogenous Stem is ex-hibited in the accompanying cuts, which represent highly 270 HOW CEOPS GEOW. magnifiod sections of a Vascular bundle or fiber from themaize-stalk. As before remarked, tlte stem is composedof a ground- work of delicate cell-tissue, in which bundlesof vascular tissue are distributed. Fig. 48 represents across section of one of these bundles, c, g, h, as well as. Fig. 48. of a portion of the surrounding cell-tissue, a, a. Thelatter consists of quite large cells, which, being but loosely-packed together, have between them considerable inter-cellular spaces, i. The vascular bundle itself is composedexternally of narrow, thick-walled cells, of which thosenearest the exterior of the stem, h, are termed bast-cells,as they correspond in character and position to the cells THE TEGKTATIVE ORGANS OP PLANTS. 271 of the bast or inner bark of our common trees; thosenearest the centre of the stem, c, are wood-cells. In themaize stem, bast and wood-cells are quite alike, andare distinguished only by their position. In other plants,they are often unlike as regards length, thickness, and^i-ability, though still, for the most part, similar in the wood-cells we observe a number of duds, d,e, f, and between these and the bast-c
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Keywords: ., bookcentury1800, bookdecade1860, booksubjectagricul, bookyear1868
