COLOR IN FLOWERING PLANTS. 89 



merely chemical, the oxygen accumulated by night being used up 

 by day. 



But the most quick-witted insects would notice them, and we 

 find that some plants have adopted them as dialects of the uni- 

 versal "flower-language." Fritz Miiller describes a Brazilian 

 lantana whose flowers last three days, and are yellow the first, 

 red the second, purple the third. A few butterflies stick their 

 tongues into the yellow and red, others visit only the red, none 

 the purple. If the flowers fell the first day, the inflorescences 

 would be less conspicuous ; if the butterflies did not appreciate 

 the change, they would lose time in searching for honey from 

 old, functionless nectaries. What may be a purely chemical phe- 

 nomenon in the hibiscus has become a constant and useful char- 

 acter. (Even more remarkable is the case described by Hilde- 

 brand of Eremurus, whose flowers open before the reproduc- 

 tive organs are mature. After the corolla is withered, stamens, 

 stigma, and nectaries become fully developed, so the less intelli- 

 gent insects, decoyed by the bright young flowers and finding 

 there no honey, leave the inflorescence to the friends who love it 

 because "it has opened its heart" to them.) 



Tannin, which causes the disagreeable taste of many petals, is 

 peculiarly abundant in cells which exhibit irritability — i. e., it is 

 easily affected by outside agencies. Petals are delicate organs, 

 and whatever irritable substance is in them is therefore the more 

 easily stimulated. Add this to the fact of their youth, and it is 

 natural that flowers should be pre-eminently variable, and alto- 

 gether possible that certain stages may be seized upon and made 

 hereditary by the selection of the innumerable army of hungry 

 insects. 



So, again, there is law all the way through. The operation of 

 entirely natural and conceivable causes leads to the permanent 

 establishment and combination of colors, odors, and forms which 

 may be protective, repulsive, imitative, attractive, or unite several 

 of these functions. And in the "continuous adjustment of in- 

 ternal to external conditions" is the evolution from alga to rose, 

 which shall by no means stop with the rose. The song of the 

 flowers is clear and true : 



" So on our heels a fresh perfection treads ; 

 A power, more strong in beauty, born of us 

 And fated to excel us, as we pass 

 In glory that old darkness; 

 — For, 'tis the eternal law, 

 That first in beauty shall be first in might." 



