340 ALTERATIONS OF COLOUR. 
the petals, the others bemg of their ordmary green 
colour. 
The occurrence of coloured bracts, as in Poinsettia, 
Bougainvillea, &c., is very common under natural con- 
ditions, and need not here be further alluded to. 
Increased intensity of colour often accompanies 
teratological changes ; an instance has just been alluded 
to in the Gesnera: the feather hyacinth, Muscari 
comosum, furnishes another illustration, the adven- 
titious pedicels being brightly coloured. 
In fasciated stems, also, of herbaceous plants, 1t not 
unfrequently happens that the upper portions of the 
stem are brightly coloured. 
The occurrence of flowers or fruits of different colours _ 
on the same plant, or even in the same cluster, 1s a 
phenomenon which does not come within the scope of 
the present book; the reader may, however, be referred 
to the excellent summary on this subject published by 
Mr. Darwin in his work on the ‘ Variation of Animals 
and Plants under Domestication.’ 
