On the Quantity of Wood-gum (Xylan) contained 

 in Different Kinds of Wood. 



BY 



J. Okumura, Nogakitshi. 



The durability of wood is of great importance for industrial 

 purposes. This durability depends not only upon the greater or 

 less density, but also upon the presence of certain chemical cons- 

 tituents. Thus a certain proportion of resinous matters will 

 increase the durability, while the presence of easily soluble 

 carbohydrates may diminish it considerably. The durability 

 consists in a certain resistance to the attacks of different kinds 

 of fungi, as Polyporus, Agaricus, etc. Resinous matters can 

 never be attacked by these fungi, but various carbohydrates, 

 as starch, wood-gum, and even cellulose are sometimes rapidly 

 dissolved by the ferments produced by these fungi which thus 

 prepare their way to penetrate into the interior of the wood. 'J 

 From this stand-point it seemed to me to be of great interest* to 

 determine the amount of wood-gum in a series of trees grown in 

 Japan. Of course the quantity of wood-gum will not be found 

 always to be a constant figure. The proportion may differ 

 somewhat between the heart-wood and bark, and also may yary 

 with the age of the tree. It is certainly of physiological interest 

 that Thomson found great differences in the amount of wood-gum 

 in sap-wood and heart-wood as seen from the following table : — 



Dried at ioo°C. 



% in dry matter. 





Sap-wood. 



Hearl-wood. 



Bctula alba L. (old) 



13-9 



19.7 



(young) 



24.9 



26.4 



Fagus sylvatica, L. (100 years old) 



8.2 



15-9 



(young) 



11. 9 



"•3 



Quevcus glandulifera, Bl. 



14.4 



10.7 



Pr units pscudocerasus, L. 



19-3 



15-4 



i) The observations of R. Hartig in this 



direction are of 



special importance. 



