F. Keeble and E. F. Armstrong 



293 



C. The Oxydases of Dianthus barbatus (Sweet William). 



(1) Ever-sporting Varieties. 



The nearest approach to a flower of this description which we have 

 found so far is that of the Sweet William (Dianthus barbatus). This 

 species presents a wide range of variety of flower colour. Pure white- 

 flowered races as well as races with purple, red and salmon colour are to 

 be found in almost every garden. In addition to races with pure white 

 flowers, others occur in which the flower is white except for a ring of 

 fine pink dots or lines across the middle of the petals. Ever-sporting 

 varieties are likewise common. They bear on one and the same inflor- 

 escence flowers of very dififerent colours. Thus in the race with which 

 we have experimented the colours of the flowers of a single plant were 

 deep magenta, strawberry, pale and streaked pink on a white ground 

 and white. In some of the white flowers a small amount of rose coloured 

 pigment occurs a little below the middle of the limb of each petal, 

 and in others the amount of pink colouration is so small that the 

 flowers are almost pure white. If this series of dififerently coloured 

 flowers of an ever-sporting variety of Sweet Williams be examined 

 for oxydase it is discovered that the amounts of oxydase present in the 

 petals of the several members of the series are strictly proportional to 

 the amounts of pigment in those members. 



As illustrated in Text-figure 2, all the coloured forms contain both 



A 



Fig. 2 



B CD 



The oxydase (benzidine) reactions of the flowers of an ever-sporting variety of 

 Dianthus barbatus (Sweet William), illustrating the parallelism between pigmentation 

 and oxydase content. 



Flower-colour : A Deep red magenta. 



B. Light red magenta (strawberry colour). 



C. Pale rose, blotched. 



D. White with trace of rose in centre. 

 [The limbs of the petals contain no pigment and no oxydase. ] 



