The elements of botany for beginners and for schools . lled Ducts, or sometimesVessels. There are all gradations betweenwood-cells and ducts, and between both theseand common cells. But in most plants thethree kinds are fairly distinct. 409. The proper cellular tissue, or ^«ro«-chyma, is the grouud-vfork of root, stem, andleaves; this is traversed, chiefly lengthwise,by the strengthening and conducting tissue,wood-cells and duct-ceUs, in the form ofbundles or threads, which, in the stems andstalks of herbs are fewer and comparativelyscattered, but in shrubs and trees so numer-rous and crowded
The elements of botany for beginners and for schools . lled Ducts, or sometimesVessels. There are all gradations betweenwood-cells and ducts, and between both theseand common cells. But in most plants thethree kinds are fairly distinct. 409. The proper cellular tissue, or ^«ro«-chyma, is the grouud-vfork of root, stem, andleaves; this is traversed, chiefly lengthwise,by the strengthening and conducting tissue,wood-cells and duct-ceUs, in the form ofbundles or threads, which, in the stems andstalks of herbs are fewer and comparativelyscattered, but in shrubs and trees so numer-rous and crowded that in the stems andall permanent parts they make a solid massof wood. They extend into and ramify inthe leaves, spreading out in a horizontalplane, as the framework of ribs and veins,wliich supports the softer cellular portion orparenchyma. 410. Wood-Cells, or Woody Fibres,consist of tubes, commonly between one andtwo thousandths, but in Pine-wood sometimes two or three hundredths,of an inch in diameter. Those from the tough bark of the Basswood,. 446 Fio. 444. Magnified wood-cells of the bark (bast-cells) of Basswood, one andpart of another. 445. Some wood-cells from the wood (and below part of a duct);and 446, a detached wood-cell of the same; equally magnified. Fig. 447. Some wood-cells from Buttonwood, Platanus, highly magnified, awhole cell and lower end of another on the left; a cell cut half away lengthwise,and half of another on the right; some pores or pits (a) seen on the left; whilei i mark sections through these on the cut surface. When living and young theprotoplasm extends into these and by minuter perforations connects across age the pits become open passages, facilitating the passage of sap and air. 134 VEGETABLE LIFE AND WORK, [SECTION 16. sliown in Fig. 444, are only the flfteen-hundredtli of an inch wide. ThoseofButtonwood (Fig. 447) are larger, and are here highly niagnifled figures show the way wood-cells are commonly put together, n
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectbotany, bookyear1887
