62 
I. NAGAI : 
upon experimental evidence, that the metal organic or complex compounds of 
reduced flavonol glucoside 
MeX 
(sugar) 
I 
( o 
/\/\_/ 
are the most important factor in the production of flower colours. The blue 
anthocyanins are complex compounds of reduced flavonol glucosides, which 
possess several hydroxyl groups belonging to the flavonol nucleus besides those 
of sugar molecules, and the metal wflth winch they are co-ordinated is probably 
calcium or magnesium, for salts of these metals are always present in the 
plant cells. The violet, violescent red or red pigments are either the analogous 
metallic complex compounds of flavonol glucosides, which contain fewer of the 
auxochrome hydroxyl groups or are a mixture of the blue pigments and their 
decomposition products by excess of acids, i.e., the red oxonium salts of R. 
WlLLSTATTEK. 
It is likely to be inferred then that the purple and red anthocyanins 
formed in the awn and in other parts of Oryza are the derivatives of the same 
chromogenic flavonol glucoside and the purple is the complex salt of the red 
anthocyanin which is formed at first in the cell by the reduction of the 
chromogenic substance. The latter part of the changes may be due to the 
action of gene R. Indeed, it can be observed that the extract of the slightly 
red coloured awn yielded a more intense red colour by reduction than that 
produced by a simple addition of hydrochloric acid, and the faintly coloured 
extract of red and purple anthocyanins that is due to isomerization, attained 
a bluish hue by the addition of ZnCL and a reddish hue by CaCb. The 
gene R' may therefore be referred to the agencies which set free the reactions 
leading to the formation of a pimple complex salt from red anthocyanin with 
the existing metallic salts in the cell. 
With respect to the colour of the paleas, the following hypothesis may 
be provided. Let B be the gene for the brown ground-colour, b for the non 
