30 J. W. Draper—Distribution of 
stock is in like manner changed by the yellow, orange and red. 
The rich blue tint of the Viola odorata, turned green by sodium 
carbonate, is bleached by the same group of rays, that is, b 
those less refraneible than the yellow. The green (chlorophyl) 
of the Hider leaf is changed by the extreme red. 
It is needless to extend this list of examples. The foregoing 
establish the principle, that every part of the spectrum displays 
activity, some vegetable colors being affected by one, others by 
er 
my expe 
Royal Society, 1856, 1857). 
n Table III. of my memoir, above referred to, it is shown 
that this mixture is affected by every ray of the spectrum; but 
by different ones with very different energy. e maximum 
is in the indigo, the action nee being more than 700 times as 
powerful as in the extreme red. 
6th.—Case of the Bending of the Stems of Plants th the Spectrum. 
It is a matter of common observation, that plants tend to 
grow toward the light. Dr. Gardner was, however, the first to 
