. American forestry. Forests and forestry. 352 AMERICAN FORESTRY ready been stated, the contents of young cells is gradually converted into an oily mass and eventually into resin. Trans- verse and longitudinal sections of older shoots show that during the winter the resin cells are filled with semi-fluid resin occurring either in the form of a thin layer or in small globules. For convenience of study, Dippel grouped the resin-containing elements in the wood of white fir into single resin cells, large groups of resin cells, and true resin canals. He briefly described the structure of the difife
. American forestry. Forests and forestry. 352 AMERICAN FORESTRY ready been stated, the contents of young cells is gradually converted into an oily mass and eventually into resin. Trans- verse and longitudinal sections of older shoots show that during the winter the resin cells are filled with semi-fluid resin occurring either in the form of a thin layer or in small globules. For convenience of study, Dippel grouped the resin-containing elements in the wood of white fir into single resin cells, large groups of resin cells, and true resin canals. He briefly described the structure of the dififerent groups, their relation to the surrounding tissue, as well as the form and function of the individual cells composing the different groups. The following are the chief facts brought out by Dippel: DESCRIPTION OF GROUPS I. Among the single resin cells mav also be included small groups of from two to four resin cells (transverse sec- tion) found in the wood of the roots and stems (Fig. i). In the latter they. :Ft^ usually occur among the thin-walled tracheids of the early wood (spring- wood of Schacht), and are seldom pres- ent among the thick-walled cells of the late-wood (fall-wood of Schacht). In wide concentric zones of roots they oc- cupy a similar position, but in narrow zones they are found either among the thick-walled tracheids of the late-wood or in the transition zone between early and late-wood. They are found in all genera of the conifer?e except in Pinus and Picea, and in structure are similar to those of the wood-parenchyma fibers in Dicotyledonous woods. The individ- ual cells composing these fibers form a perpendicular row of elements that have either horizontal or oblique cross-walls and contain numerous simple pits. Where the side-walls of such elements are adjacent to other elements of the same order or border on pith ray cells the pits are invariably simple; where they are adjacent to tracheids the pits within the walls of tracheids are bor- dered, and wi
Size: 1357px × 1842px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1910, booksubjectforestsandforestry
