934 JOURNAL OF FORESTRY 



of each species. The characters described for hardwoods are size of 

 tree; color of heartwood ; width of sapwood ; distinctness of annual 

 rings ; presence of pith flecks or other abnormalities ; number of pores 

 per square millimeter ; outline of pores on cross section ; arrangement of 

 pores ; length of vessel segments ; nature of perforations ; nature of 

 pits ; diameter and thickness of walls, and length of wood fibers ; dis- 

 tribution of parenchyma ; height and diameter of rays ; color of water 

 abstract and presence or absence of flavone. The descriptions of the 

 wood of the gymnosperms are modified to suit the difference in struct- 

 ure, but like those of the dicotyledenous species, represent a vast amount 

 of work, especially microscopic measurements. 



The key for identification is so arranged as to show differences 

 between species as far as possible, but in some cases several species, 

 and even several genera, are included in a group without further 

 subdivision. 



A chapter entitled "Summary and Critical Remarks from the Climatic 

 Point of View" discusses the following: Occurrence of flavone, fluores- 

 cence of water extract, lamellated pith, ripple marks, intercellular 

 canals in dicotyledonous woods, vessels, wood fibers, wood parenchyma, 

 pith rays. At the end of this chapter the author gives the following 

 summary based on a comparison of Formosan woods with those of 

 tropical (Philippine) and temperature (Japan) climates: 



SUMMARY 



1. Investigation of flavone content in wood is very important for 

 diagnostic purposes. 



2. Ripple marks occur more frecjuently in woods of the tropical zone 

 than in those of the temperate zone. 



.3. Intercellular canals occur only in woods of the tropics. 



4. Number of pores per unit area gradually decreases toward the 

 tropics but the diameter of pores follows an inverse course; in other 

 words tropical woods are coarser in texture than those of the tem- 

 perate zone. 



5. Scalariform perforation of vessels occurs more frequently in the 

 tropics than in the temperate zone ; this shows that tropical trees to be 

 of higher order. 



6. Spiral thickenings in vessels occur more frequently in the tem- 

 perate zone than in the tropical zone. 



