38 PROPERTIES OF WOOD. 



the vertical resin-ducts appear as fine bright dots in the 

 darker summer-wood. Fine lines that are bright or dark 

 according to the angle of incidence of the light in the radial 

 direction denote horizontal medullary rays. Spring-wood is 

 soft and pale and suddenly passes into summer-wood, repeti- 

 tions of soft, pale wood also occur in the latter (Fig. 22). 





Fig. 28. Type of Pinewood. Pinus 



Fig. 22.-Type of Sprucewood. Pieea (secti(m Taeda) Pitchpine ( PMli 



and Pinus (section Pinaster), Larix pa i ustriis ) from the south-east of 

 and Pseudotmga. North America . 



Radial Section. The resin-ducts appear as fine lines (but 

 are not clearly shown in the plate). The medullary rays are 

 faintly visible and render the radial section of conifers lustrous. 

 The annual rings are clearly seen owing to the difference 

 between the dark summer-wood and pale spring-wood. 



Tangential Section. The resin-ducts, especially when they 

 occur in the summer-wood, show distinctly ;is longer or shorter 

 lines. The annual rings are also distinct. 



