16 
I. NAGAI : 
and exposed to day light, a deep violet-red colour develops. The coloured 
scales were removed and tlie white portions were kept iu the same manner 
as in the previous experiment with the common onion bulbs. No red pigment 
was formed during the experiment which lasted for two weeks. The bulbs in 
the control became deep green and the treated ones were wliite. Alcoholic 
extracts were prepared, and the flavone content was examined. They showed : 
Treated No reaction 
Control Trace of pink colour 
Here the flavone was formed in extremely slight amount even when the 
light and the air relation was normal. 
5. A Group of Substances of Unknown Chemical Nature 
as the Chromogen of Anthocyanins and 
Beddish Brown Pigments. 
A body of evidences accumulated by the different investigators show 1 that 
a group of chromogenic substance is present in plants which gives rise to 
anthocyanin-like pigments as well as the brown pigments. 
Wolff and Bouchermann (1915)- observed the presence of a cluomogenic 
substance in a number of plants which are sensitive to the action of laccase 
yielding the brown pigment. The phenomena observed in iodine colour tests 
are always preceded by the action of a laccase. The authors considered that 
the chromogens are of the same kind in different plants and the brown 
pigments which are formed in various plants or organs might be regarded as 
products of oxidation. Shibata 3 obtained the chromogenic substance horn a 
1. Malyezin, Ph., Sur 1 ’origine de la colour des raisins rouges. Comp. Rend. Acad. Sei. 
Paris. 147:348, 1908 ; Labokde, J., Sur 1 ’origine de la matière colorante des raisins rouges et 
autres organes végétaux, Ibid. 146:1411, 1908 ; Dezani, S., Le sostanze cromogene delT uva 
bianca. Staz. sper. agr. ital., Modena. 43:328, 1910 (cited in Atkins, W. R. G., Researches in 
Plant Physiology. 1916) (also in Jour. Chem. Soc, Abstract 100:223, 1911.) ; Keegan, P. Q, The 
Chemistry of the Flower Pigments. Chem. News. 107:181, 1913 ; Tswett. M., Zur Kenntnis des 
vegetabilischen Chamæleons. Ber. d. d. bot. Gesell, 32:61, 1914 ; Tswett. M., Beiträge zur 
Kenntnis der Anthocyane. Ueber künstriches Antliocyan. Bioch. Zeit. 58:225, 1913. 
2. Wolff, J. and Rouchekmann, N., Sur les propriétés d’un chromogène universellement 
répandu dans les végétaux. Comp. Rend. Acad. Sei. Paris. 161:399, 1915 : IVolff, J., Phénomènes 
d’ oxidation et de réduction portant sur les chromogènes des végétaux. Ibid. 160:716, 1915. 
3. Shibata, K., Bot. Mag. Tokyo. 31:1919. A brief note in Japanese. 
