ANATOMY, 



often sufficient to determine the relative value of the wood. 

 The relative dimensions of the spring- and summer-wood, the 

 width of the annual rings, and their uniformity or want of uni- 

 formitv, should he carefully noted. 



Fig. 2. 



(a) Belatire I)i»t('nsions of Sprinrj- and Summer-wood. 



If the spring- and summer-wood were similarly organized it 

 would be impossible to distinguish the annual rings on a trans- 

 verse section of a piece of wood. It has, however, been already 

 noted that in many 

 broad-leaved woods the 

 vessels in the spring- 

 wood are large and 

 numerous, and the 

 wood-fibres wider and 

 thinner-walled than in 

 the summer -wood, in 

 which, usually, the pores 

 are small and the fibres 

 thick- walled. As, there- 

 fore, the denser zone of 

 wood A (figs. 2, 3 and 4) 

 is immediately adjacent 

 to the porous spring- 

 zone B, the boundary 

 of the annual ring is 

 generally very obvious. 

 It is difiicult to distin- 

 guish the annual rings 

 in woods which form little summer-wood, and with pores 

 which are usually evenly distributed over the whole annual 

 zone, as, for instance, in birch, hornbeam, maples, poplars, 

 alders, limes, horse-chestnut, willows, fruit-trees, &c. 



Coniferous wood (fig. 4) is without pores ; but, on the other 

 hand, the width and thickness of the walls of the summer-wood 

 A are very difterent from those of the spring-zone B, so that the 

 annual rings in this case are very sharply defined. As a rule, 

 therefore, annual rings are clearest in the case of ring-pored 



