134 



VEGETABLE LIFE AND WORK. [SECTION 16. 



shown ill Fig. 444, are oiilj the fifteen-hundredth of an ineh wide. Tliose 

 of Buttonwood (Fig. 447) are larger, and are liere highly magnilied besides. 

 The figures show the way wood-eells are commonly put together, namely, 

 with their tapering ends overlapping each other, — spliced together, as it 

 were, — thus giving more strength and toughness. 1b hard woods, such 

 as Hickory and Oak, the walls of these tubes arc very thick, as well as 

 dense ; while in soft woods, such as White-Pine and Basswood, they are 

 thinner. 



411. Wood-cells in the bark are generally longer, finer, and tougher 

 than those of the proper wood, and a])pear more like fibres. For example, 

 Fig. 44G represents a cell of the wood of Basswood of average length, and 

 Fig. 444 one (and part of another) of the fibrous bark, both drawn to the 

 same scale. As these long cells form the principal part of fibrous bark, or 

 bast, they are named Bast-cells or Bast-fibres. These give the great tough- 

 ness and flexibility to the inner bark of Basswood (i. e. Bast-wood) and of 

 Leatherwood ; and they furnish the invaluable fibres of llax and hemp ; 



the proper wood of their stems 

 being tender, brittle, and de- 

 stroyed by the jiroccsses which 

 separate for use the tough and 

 slender bast-cells. In Leather- 

 wood (Dirca) the bast-cells are 

 remarkably slender. A view of 

 one, if magnified on the scale 

 of Fig. 444, would be a foot 

 and a half long. 

 412. The wood-cells of Pines, 

 other Coniferous trees, have on two of their sides 

 ped markings (Fig. 44S-450) by which that kind of 

 ■wood is recognizable. 



41.3. Ducts, also called Vessels, are mostly larger 

 than wood-cells : indeed, some of them, as in Red Oak, 

 have calibre large enough to be discerned on a cross 

 section by the naked eye. They make the visible porosity 

 of such kinds of wood. This is particularly the case with 

 Dotted ducts (Fig. 451, 452), the surface of which 

 appears as if riddled with round or oval pores. Such 

 ducts are commonly made up of a row of large cells more 

 or Irss confluent into a tube. 



Scatariform ducts (Fig. 458, 459), common in Ferns, 

 and generally angled by mutual pressure in the bundles, 



ind more or less of a 

 rery peculiar disk-shi 



Fig. 443. Magnified bit of a pine-shaving, taken pai-allel with the silver graia 

 449. Separate whole wood-cell, more magnified. 450. Same, still more magnified; 

 both sections represented : a, di.sks in section, b, m face. 



Fig 451, 452. A large and a .smaller dotted duct from Grape-Vine. 



