52 



We have also shown that it is just as natural under suitable 

 conditions for the orreen color to dissolve into a clear 

 yellow. 



In our example, the violet exists in the cell sap, and the 

 chloroplastids are tinged with green at the same time. It is 

 a question simply as to which shall prevail, and that will 

 depend upon chemical conditions at present not sufficiently 

 understood. In our Iris the violet prevails. 



The green upper portion of the claw fades away, leaving 

 a few white streaks extending into the violet blade ; this is 

 a common sequence : green to white ; with age that portion 

 of the sepal at the height of the declined style becomes 

 somewhat yellowish, that is, a very small })art of the long- 

 green claw has transmuted its chlorophyl to Xanthophyl, 

 and that is all the yellow there is in the flower, the inner 

 segments or petals being of the same green and purple, 

 with faint whitish streaks only. 



The yellow species upon examination will be found to 

 have always more or less of purple-brown on the claw^*, this 

 color being a purple or violet modified 1)y the yellow. 

 Some species are wholly of this mixed purple-browni, as 

 shown in Iris fulva. It appears, therefore, that the two 

 pigments really exist in all the species, and one is just as 

 likely to be as prominent as the other, according as climate 

 or other circumstances favor. 



The reason why yellow is more conunon than red or l)lue 

 I apprehend, is because the ordinary yellow is dependent 

 upon a previous green generally present in the flo^ver bud, 

 and when this recedes its yellow constituent is apt to 

 remain. I have not infrequently seen a white, lavender, or 

 red-purple flower, when the petals first })eep out of the 

 calyx, to be more or less yellow temporarily. 



In observing the colors of the common garden Sweet Pea 

 one frequently remarks a variegation in the same flower : 

 the banner being of one hue an<l the wings and petals of 

 another. The banner is the outer petal which enfolds and 



