18 
I. NAGAI : 
added in tlie same proportion as before, for the cliromogenic substance P. 
After the treated extracts were cool, the colours of the extracts were compared 
with those of the standard colours and recorded. The standard colours were 
prepared in the following manner. 
Twenty five cc of quercetin dissolved in absolute alcohol, were reduced 
with five cc of concentrated hydrochloric acid and about 0.5 grams of magnesium 
powder. 
Colour scale Concentration of quercetin 
I 
I: 1,000 
II 
I: 2,000 
III 
I: 8,000 
IV 
I: 5,000 
Y 
I: 10,000 
VI 
1: 20,000 
Thus the relative value of the chromogen content in the material was 
approximately determined. The result of a survey established the following 
fact. 
The cliromogenic substance P can be detected in different parts of plants, 
i.e., the leaf, stem, shoot, rhizome, bark, wood, white petals, perigone, seed 
coat, mesocarp, stigma etc. 
It occurs quite independently or in company with the cliromogenic sub¬ 
stance F. Even in the same plant, the distribution of the two chromogens is 
quite distinct in different organs. 
Light seems to have no direct relation to the distribution of the chromo- 
genic substance P unlike the case of the chromogenic substance F (flavones). 1 
For, the underground parts and the interior portions of the upper ground 
tissues of many plants contain a considerable amount of the chromogenic 
substance P. The bark of young twigs, the seed of immature seeds which 
ultimately become brown, red or black when fully mature, the young fruits 
and berries of many of the cultivated fruit trees are especially rich in the 
chromogenic substance P. Thus, for example : 
1. Shibata, K. Nagai, I. and Kishida, M., The Occurrence and Physiological Significance of 
Playone Derivatives in Plants. Jour. Biol. Chem. 28:93, 1916. 
