ox THE CAUSE OF THE DARKENING OF THE HEART- 

 WOOD OF CRYPTOMERIA JAPONICA DON^ 



By MiTsunaga Fujioka and Kenzo Takahashi 

 P or est Experiment Station, Megiiro, near Tokyo, Japan 



Of all the conifers, "Sugi" (Cryptomeria japonica Don.) has the 

 most extensive range in Japan, ranking second only to "Akamatsu" 

 {Pins densiflora S. et Z.). Owing to its longevity and rapidity of 

 growth it attains a considerable size, the largest being 120 feet in 

 height. Many specimens of "Sugi" are known among the people of 

 some localities as gigantic trees, together with those of "Kusii" (Cin- 

 namoniim camphora Nees. et Eberm.), "Benihi" (Chamaecyparis for- 

 mosensis Matsum.), "Icho" (Ginkgo biolaba L.)» "Shii" (Pasania cus- 

 pidata Oerst.), "Mukunoki" (Aphananthe aspera Planch.), "Keyaki" 

 [Zerkowa serrata Mak.), and "Katsiira" ( Cercidiphyllum japonicum 

 S. et Z.). There are beautiful natural stands of this species in the 

 State Forest of Nagakisawa in Akita Prefecture, and the natural 

 growth of the same in the State Forests of Yakushima is quite fa- 

 mous for the production of figured and close-grained timber. Be- 

 cause the tree is easily propagated and the wood is so widely used it 

 has been cultivated for a long time throughout Shikoku, Honshu, and 

 Kyushu. Beautiful artificial forests, of which those privately owned 

 in the Yoshino district of Nara Prefecture are the most notable, are 

 found here and there in all districts. 



Tlius, because of the many uses to which it may be put and the 

 high respect in which it is held, "Sugi" is the commonest and most 

 important of Japanese timber trees. Tt has therefore been the sub- 

 ject of many studies in regard to raising of seedlings, replanting, dis- 

 eases, growth, yield, and technical properties of the timber. We have 

 been interested in making a somewhat detailed stud}- of the cause of 

 the darkening of the heartwood, a study which may have a great 

 bearing on our forestry from the economical point of view. The 

 present investigation may provide data which will be of value to those 



^ This paper is an abstract from the article in Japanese of the same title, with 

 two plates, published in the Bulletin of the Forest Experiment Station, No. 16, 

 1017, pp. 1-78. 



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