460 THE AMERICAN NATURALIST. [Vol. XXXVII. 



sap. Both carotin and /8-xanthophyll occur in species of Ranun- 

 culus, Verba-- . \:-..<tris and Rides an renin. The 

 /3-xanthophvll can be obtained in a yellow solution by boiling in 

 water the peel of the lemon. It becomes brown-colored with 

 sulphuric acid and with ammonia a deeper yellow. This pig- 

 ment was first isolated from the flowers of the dahlia nearly half 

 a century ago. 



In the chloroplasts of golden yellow-leaved plants, as Sajn- 

 bucus and Evonymus, Kohl finds yet another yellow pigment 

 largely soluble in water to which he gives the name of phyllo- 

 fuscin. In addition to this pigment he finds in yellow leaves 

 much carotin, and more or less /3-xanthophyll, but no u-xantho- 

 phyll or chlorophyll. Though they contain no chlorophyll such 

 plants grow and perform the work of assimilation, in which 

 process the chief part must be ascribed to carotin. Finally in 

 yellow autumn leaves there is little or no chlorophyll, about 



phyll and much /?-xanthophyll. 



The yellow plastids of flowers are usually round and small, 

 though sometimes angular as Tropaeolum. Several other modi- 



plastids of the tomato gave the usual reaction for carotin. In 

 yellow leaves the plastids are round, but in autumnal yellow 

 leaves they occur in irregular masses. The scarlet poppy, tulip 

 and fire red canna owe their colors to a mixture of yellow plas- 

 tids and red cell sap. On the other hand dingy or dull colors 

 result from a combination of violet sap with yellow granules. 

 Ant/ioeran. — The red and blue colors of leaves, fruits and 



