DETECTION OF FLAVONE AND THE FLUORESCENCE OF 



THE WATERY EXTRACT OF WOODS AS AIDS 



IN IDENTIFICATION 



By Dr. R. Kanehira 



Director of Forest Bxperiment Station, Government of Formosa, Japan 



Various means of identifying woods are in practice, but only recently 

 has a systematic attempt been made to use for this purpose the detec- 

 tion of flavone and the fluorescence of the water extract. The writer 

 and a few others, notably Prof. Fujioka, have examined these 

 phenomena in a great many kinds of woods and have found them of 

 considerable diagnostic value. The present paper embodies the results 

 of investigations of specimens of North American woods contributed 

 to this station by the U. S. Department of Agriculture and comprising 

 69 species, 39 genera, and 18 families. 



Detection of Flavone. — The occurrence of flavone derivatives in 

 plants is almost exclusively limited to the epidermis and peripheral 

 parenchymatous layer of the aerial parts, with few exceptions on 

 record, in which a considerable amount is also found in the bark and 

 the wood. The writer investigated the American woods by producing 

 anthocyanin solution through reduction of flavone derivatives in wood. 

 The method of reduction is as follows : 5 to 10 cc. of alcohol extract, 

 prepared by heating the wood chips with alcohol, are acidified by an 

 adition of five to ten drops of concentrated hydrochloric acid. A few 

 cc. of the mixture are placed in a test tube with a drop of mercury the 

 size of a pea, and a small amount of metallic magnesium powder. 

 Reduction takes place with a vigorous generation of hydrogen gas 

 whereby the mixture becomes colored and often intensified by leaving 

 over night. The comparative determination of flavone content is 

 rather difficult and therefore only three grades of coloration have been 

 distinguished, namely, strongly colored (ftSfi)' moderately colored 

 (##), and faintly colored (#). 



Fluorescence of the Watery Extract of Wood. — The fluorescence of 

 watery extracts of certain species of plants is a familiar phenomenon. 

 The best known example of the fluorescence of wood extract is the 

 736 



