1887-88.] Colouring Matters of Leaves and Floivers. 305 



depreciated, must be taken as an indication that the interest 

 and criticism then aroused stimulated me to consider the 

 question afresh and in more detail. This subsequent work 

 has enabled me to see more clearly, in regard to colour, at 

 once the immense power of selection, and the limits to its 

 action. This I have attempted to bring out in this last part 

 of my paper. It would not perhaps be incorrect to assert 

 that next to the fact of evolution comes the fact of natural 

 selection — more than any other realised within the century, 

 to modify all our manners of learning, our thoughts, and 

 our future. Yet, notwithstanding its importance, however 

 we look at it, natural selection is only a selecting ; having 

 recognised its potency, we need to push back our inquiry, to 

 find out as to the mystery of variation, as to those causes 

 or tendencies which, when laid hold of by selection, and 

 impressed by environment, have given to us progress and 

 evolution of every advanced type, of even simpler organisms 

 out of every organic structure. 



Literature consulted on Plant-Colour. 



1876. AcKROTD, " Metachromism," Nature, xiii. p. 298. 



1886. Akxadd, "Leaf Colour," Acad, de Sciences, May 17, 1876; 



rev. Eng. Mechanic, xli. p. 508. 

 1885. Baccarin'I, "Flower Colours," Ann. Inst. Bat. Roma, ii., 



1885; rev. Jour. Roij. Mic. Soc. Lond., p. 268, 1886. 

 1872. Batalix, "Light," Bot. Zeit., 1872. 



Bennett, A. W., " Scent and Colour," Pop. Sci. Rev., xiv. 



pp. 113125. 



1879. Bonnier, "Flowers and Insects," Bull. Soc. Bot. France, 



xxvi. p. 68. 



1880. Bonnier, "Arctic Flora," Ann. Sc. Nat., t. x. ; rev. Bih. 



Bull. Soc. Bot. France, xxix. 

 1880. Bonnier, "Green Flowers," Bull. Soc. Bot. France, xxvi. 



p. 249. 

 1880. Bonnier, "Distribution and Soil," Bull. Soc. Bot. France, 



xxvi. p. 20. 

 BouGLER, G. S., " Scent and Colour," Nature, vol. xviii. 



p. 427; X. 620. 

 1876. BtroHAN, " Spring Flower Colours," Trans. Bot. Soc. Fdin., 



xii. p. 441. 

 1876. BucHAN, "Spring Flower Colours," Nature, xiii. p. 249. 

 1880. Brown, "Vine Leaves, &c.," Text-Book of Botany. 



