July, 1920.] 



OGUBA:— GROWTH IN THICKNESS. 



109 



15. From these facts, we may conclude that the size of xylem- 

 elements changes considerably in different parts of the tree. For the 

 diagnostic purpose of different kinds of wood, it will be dangerous to 

 adopt the dimensions of xylem-elements, without considering age and 

 height of the wood, from which these elements are taken. 



In closing, I should like to express my cordial thanks to Proffessor 

 Fujn for his kind advise and criticism throughout the work. My 

 hearty thanks are also due to Prof. Fujisawa, Director of the College 

 of Science, Dr. Nishigaki, Lecturer in College of Agriculture, Mr. 

 Hattori, Chief of the Department of Forestry, Government of Formosa, 

 and other gentlemen, who have provided me for the present research 

 with many valuable materials, or given me several advices of facilities. 



Botanical Institute, College of Science. 

 Tokyo Imperial University. 



