LA W OF PROGRESSIVE COLOURA TION. 57 



but it often reverts to white or even to a faint yellow. 

 In Scilla, however, including our common wild hya- 

 cinth (S. nutans), the deep tubular flowers, composed 

 of perianth pieces with long claws, are usually blue, 

 rarely pink or white ; while in Hyacinthus and Mus- 

 cari, which have a united bell-shaped or globular 

 blossom, formed by the coalescence of the sepals and 

 petals, dark-blue and ultramarine are the prevalent 



FIG. 20. Flowers of simplest typical lily (Gagta lutea) ; primitive yellow. 



tones. Meadow saffron (Colchicum autumnale), which 

 has also a united tube and very deep underground 

 ovary, is a fine reddish purple : its stamens secrete 

 honey. 



The Iridece and Amaryllidece are more advanced 

 than the lilies, in that they possess inferior ovaries 

 in other words, their perianth tube has coalesced with 

 the walls of the inclosed carpels. In many cases, 



