THE COLORS OF FLOWERS. 387 



or white, yellowish varieties, indicating an approach to the xanthic 

 series, are sometimes found in gardens. The auricula, which is 

 originally yellow, passes to reddish-brown, to green, and to a sort 

 of violet, but never reaches pure blue; and single petals occasion- 

 ally give suggestions of both series in distinct parts of their surfaces. 



Some surprise may be felt that white does not figure in De Can- 

 dolle's table. This is because an absolutely white color does not 

 seem to exist in any flower. The fact may be shown by placing some 

 flowers supposed to be of the purest white, like the lily, the white 

 campanula, or the wood anemone, on a leaf of clear white paper. 

 It will be found that the white of the corolla is really washed with 

 yellow, blue, or orange, according to what flower is taken. If the 

 tint does not appear distinct, infusions of the corollas in alcohol 

 will present tones unmistakably yellow or red, etc. "White flowers 

 are therefore flowers with tints appertaining to one of De Can- 

 dolle's series, but albinized, as if they were etiolated. A small 

 number of flowers begin white, and are subsequently colored under 

 the action of light. The Cheiranthus chameleo passes from white 

 to citron-yellow and a slightly violet-red; the JEnothera tetraptera, 

 at first white, becomes rose and then almost red; the petals of the 

 Indian tamarind are white the first day and yellow the second; 

 and the corolla of the Cobea scandens comes out greenish-white 

 and turns to violet the second day. The most remarkable plant 

 in this respect is Hibiscus mutabilis, which Humph calls the hourly 

 flower, because it starts white, turns flesh-color toward noon, and 

 becomes red at sunset. 



In his recent work on Plants and their Cosmic Media, M. Cos- 

 tantin has some remarks concerning the precocity of various races 

 and the tint of their flowers. Hoffmann made observations on 

 this point for several years. He remarked, as the result of eight 

 years' observation, that the common lilac with white flowers blooms 

 on an average six days earlier than the normal form with purple 

 flowers. This might be a curious anomaly with no bearing, but 

 the more we advance in the study of Nature the more we perceive 

 that all phenomena, even the most insignificant, deserve to be ex- 

 amined. Similar results have been observed in varieties of radish 

 (Raphanus raphanistrum) and of saffron (Crocus vernus); in the 

 former the white flowers expand on an average of sixteen days 

 earlier than the yellow ones (twelve years of observation), and in 

 the latter plant the difference is four days. 



These changes of tint sometimes appear to depend on the tem- 

 perature. Thus, the white lilac was obtained by horticulturists 

 under the influence of a temperature of between 30 and 35 C. 

 We can not, however, affirm that spontaneous races with white flow- 



