MACROSCOPIC STRUCTURE. :2 ( .) 



10. Species of Hornbeam (Carpiny*) 

 (American, Asiatic and European.) 



Transverse Section. The ordinary medullary rays are very 

 line and hardly visihle ; where several unite to form a band, a 

 dull, broad, compound ray occurs. The number of these 

 broad rays is very variable, depending on the individuality of 

 a tree and its locality ; many pieces of hornbeam-wood have 

 no broad rays, while in other pieces they are numerous. 

 They traverse the wood in slightly curved lines, owing to the 

 waviness of the annual zones. The annual rings are not 

 very distinct, as the summer- wood is but slightly darker than 

 the spring-wood. 



Radial Section. The vessels, annual rings, and line 

 medullary rays are scarcely visible ; the compound rays are 

 dull, broad bands, or parts of bands, but are very distinct. 



Tangential Section. The zones of summer-wood appear as 

 zigzag bands, of which broader or narrower parts may be 

 seen, according to the direction of the section. The com- 

 pound medullary rays appear as thick, dark, dull lines of 

 various length. 



Sapwood and heartwood of similar colour. 



11. Species of Alder (Alnua). 

 (European, American and Asiatic.) 



Transverse Section. The vessels and line medullary r;i y h 

 are invisible. The compound rays, like those of the horn- 

 beam, are very distinct but often few in number though 

 sometimes numerous, and thus alderwood is easily recogniz- 

 able. The annual rings are fairly distinct, owing to the light 

 sapwood and darker heartwood. The wood is easily distin- 

 guished from that of hornbeam by the heaviness of the latter. 



Radial Section. The annual rings are most distinct along 

 the compound rays, which appear as broad dull bands, or 

 parts of bands, running through the wood. The line rays 

 are scarcely visible. 



Tangential Section. The annual rings are distinct, especi- 

 ally at their points of intersection by the compound rays, 



