36 



I. NAGAI 



a. Bi'oNvu \\lieu l'ull\' lüatiu-e. 



1). Faint yellow -svlieii fuUv matui-e. 

 The brown and fcdut AeUow awns are gieen when young and the 

 alcoholic extract of the gi'een material of the brown avm \-ields a distinct red 

 colour by reduction but that of tlie faint yellow, only a shghtly red tinge. 

 If oxidase is added to the exti-act, a marked brown colom- is produced in the 

 former, while in the hxtter, practically none. It provas that the colom- of the bro^^■n 

 awn is due to the pigment jjroduced by the oxidation of the chxomogenic 

 substance at the end of the gi'owing period of the plant. The exti'act of the 

 matured brown a^v^l gives also a distinct reduction colour showing that a 

 pai-t of the clu-omogeuie substance remains without undergoing any serious 

 change. In the matm-ed awn, the bro^\•nish yellow substance, sometimes in 

 aggi'egates, filLs the cell, and when ti-eated with ammonia, yields a deep yellow 

 colom-. The relative strength of the chromogeu content of certain varieties 

 are given below. 



Table 14. 



CJiromogeD tontent of the extract of immature green awn of Orym saUva. 



Unhke the awn, the leaf does not vary ■\-er\- widol\- in the clu'omogeu 

 content. The result of the tests made over 120 vaiieties at the middle of 

 August, 1919, is given in Table 15. 



1. Pressecl sap of tLe radisli root and hydrogen peroxide is added. 



