548 JOURNAL OF THE ROYAL HORTICULTURAL SOCIETY. 



ised products — i.e. made by the plant itself. Nevertheless, as high 

 or low nutrition, prolonged and clear sunlight, as well as tem- 

 peratures, have marked influences upon the colours of flowers, if 

 he cannot alter the sunlight, the florist has one means, at least, 

 at his disposal — namely, the ingredients of the soil. As an 

 example of marked atmospheric influences is the well-known 

 fact of the greater brilliancy of flowers in high latitudes and 

 altitudes. MM. Bonnier and Flahault have shown that this is 

 indirectly due to the enhanced assimilative powers of the foliage 

 in consequence of the prolonged sunlight, by means of which the 

 flower-making and flower-colouring materials are increased. 

 Oxidisation under the action of light has been thought to be 

 another cause of change in colour, as in the case of the change- 

 able Hibiscus, which is white in the morning, pink at noon, and 

 bright red by sundown. Again, a species of Phlox with pink 

 flowers is of a light blue colour at first at 5 a.m., but by 9 or 10 a.m. 

 acquires its proper colour, the clump which catches the sun's 

 rays first being the first to change, as is also the case with 

 Chrysanthemums. Thus the variety already alluded to, called 

 the Changeable Buff, introduced by Reeves in 1824, commences 

 yellow, but passes into a pinky orange as the flower expands. 

 Again, the magnificent Etoile de Lyon bears two kinds of flowers, 

 the crown or single buds being nearly a pure white, while 

 terminal buds are described as a lilac-rose. One cannot as yet 

 assign any definite cause to account for these differences, but 

 can only suggest that they may be due to some obscure differences 

 in nutrition. Mr. Lowe describes Titania as a sport from the 

 white Pompon Modele. It has blooms which are white at first, 

 and then become pink, with the centre of the bloom remaining 

 white.* Again, Mr. Buss speaks of Lady Dorothy as being of a 

 pretty tint of fawn flushed with pink. When grown for late 

 flowering, and with all its flower buds left on, it comes more of 

 a yellow colour than fawn, apparently indicating a tendency to 

 reversion. I remarked that the colours of flowers are due to 

 chemical substances organised by the plant itself ; and Professor 

 Sachs came to the conclusion that it is the ultra-violet rays of 

 the solar spectrum which have some special power in making 

 flower substances. We know very little about these particular 

 rays in their relation to plant life ; but judging from the fact 

 * Gard. Chron. Feb. 23, 1878, p. 242. 



