A GENETICG-PHYSIOLOGICAL STUDY ON THE FORMATION ETC. 
15 
window to receive direct sunlight. Three days after the experiment was set 
up, chlorophyll developed in the seedlings in C and D ; the deep purple 
pigment was also formed in the latter. None of the pigment were formed in 
A. On fourth day, a slight purple colour was observed in C but in A and 
B, it failed to appear. In the same day, the chamber B was opened to 
allow normal air. Two days later (on the sixth day) the seedlings in A 
remained still without the pigment. In B, chlorophyll was found in the 
cotyledons but no purple pigment in the shoots. In C, the development of 
the purple pigment was still feeble, whereas in D (control), all the seedlings 
were deeply coloured. 
It is a well known fact that the leaf scale of the onion bulb becomes 
yellow on exposure to light. It is chiefly due to the formation of quercetin. 1 
If, however, the bulbs of which already coloured scales were removed, were 
kept in the closed chamber filled with hydrogen gas, the formation of flavone 
was inhibited. The bulbs were cut in halves and the coloured scales were 
removed. The halves were kept in the closed glass chamber in which the air 
was replaced by hydrogen gas and the other halves were kept for the control 
experiment. They were kept for sixteen days during which the gas was 
renewed once. Neither yellow nor green pigment was found except in the 
control specimens. When the chambers were opened, the bulbs were turgid, 
but became soft immediately after the air was let in. An equal weight of 
the scales was taken from the treated and control samples and extraction was 
made with equal volmes of a weak alcohol. The extracts so prepared, were 
reduced by means of hydrochloric acid and magnesium powder in the usual 
manner. They gave the following flavone reactions : 
Treated Trace of pink colour. 
Control Red. 
It showed that normal ah* is essential to the development of flavone in 
the leaf scale of the bulb of onion even when light is amply supplied. 
The bulbs of AUium Ledebourianum, a common weed in certain parts of 
Japan, are white when they are grown in the ground, but they are dug out 
1. Perkin, A. G. and Hummel, J. J., Occurrence of Quercetin in the Outer Skin of the 
Bulb of the Onion (Allium cepa). Chem. Soc. Trans. 69:1295, 1896. 
