A GENETICCi-PHYSIOLOGICAL STUDY ON THE FORMATION ETC. 15 



wiiuliiw to receive direct suulight. Tlu-oe clays after the experiment was set 

 up, clilor>)pliyll clevelops<l in the sec{lllnfi;s in C and I> ; the deep purple 

 pigment w;i3 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 fjiiled t<) appsar. lu tlie same day, the chamber B was opened to 

 allow normal air. Two days later (on the sixth day) the saedlings in A 

 remained stiU without the pigment. In B, chlorophyll was found in the 

 cotyledons but no pnrple pigment in the shoots. In C, the development of 

 the pui-ple pigment was still feeble, whereas in D (control), all the seedlings 

 were deeply colom-ed. 



It is a well known fact that the leaf scale of the onion bulb becomes 

 yellow on exposm-e to light. It is chiefly due to the formation of quercstin.' 

 If, however, the bulbs of which ali'eady colom-ed scales were removed, were 

 kept in the closed chamber filled ^^•ith hych-ogen 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 wliich the air 

 was replaced by hydi'ogen gas and the other lialves were kept for the control 

 experiment. They were kept for sixteen daj-s dming which the gas was 

 renewed once. Neither yellow nor gi'een pigment was found except in the 

 control specimens. When the chambei-s were opened, the bulbs were tiu-gid, 

 but liecame soft immediately after the air was let in. An equal weight of 

 the scales was taken fi'om the ti-eated and conti-ol samples and exti-action was 

 made with equal volmes of a weak alcohol. Tlie exti-a«ts so prepared, were 

 reduced by means of hych'ochloric acid and magnesium powder in the usual 

 manner. They gave the following flavone reactions : 



Ti-eatetl Ti-ace of pink coloiu-. 



Conti-ol lied. 



It showed that normal aü" is essential to the development of flavone in 

 the leaf scale of the bulb of onion even when light is amply supplied. 



Tlie bulbs of AUium Ledchourianum, a common weed in certain pai-ts of 

 Japan, ai-e white when they ai-e gi'own in the gi'ound, but they ai"e dug out 



1. Perktm, a. G. ftncl HrsniEL, J. J., Occiurence of Quercetin in the Outer Skin of the 

 Bulb of the Onion (.tUiiim cep.-i). Chtm. Soc. Trans. C9 : 1295, 1896. 



