296 Oxydases and Pigments of Plants 



exist. In the one type the white flowers are rich in oxydase and from 

 the other, as judged by the reactions with benzidine and a-naphthol, 

 oxydase is absent. We hope by the application of these methods to the 

 flowers of the many albinos which occur in cultivation and in the wild 

 state to ascertain whether one or the other type is of more frequent 

 occurrence in nature. 



E. The Localisation of Oxydases in the Tissues of the Flower 

 {Primula sinensis). 



We return now to Primula sinensis. In order to complete our 

 survey of the oxydases of the flower, and before proceeding to discuss 

 the oxydase content of dominant white flowers, we will describe briefly 

 the localisation of the oxydases present in coloured and recessive 

 white forms. The distribution of the epidermal oxydase in the petals is 

 definitely circumscribed. The epidermal oxydase is confined to the epi- 

 dermal cells and the hairs which are outgrowths from these cells. The 

 distribution of the bundle oxydase is less sharply defined. By treat- 

 ing tangential sections of the petals with the reagent, oxydase may 

 be seen to follow the veins throughout their whole course and to 

 extend to their finest ramifications. If a section which exposes one of 

 the finer veins be treated with benzidine and then examined micro- 

 scopically the brown granular or needle-like products of the interaction 

 of the reagent and the oxydase are seen as dense masses in the elongated 

 cells of the bundle sheath — which cells are more deeply stained than 

 any others. These elongated cells are wrapped around and also extend 

 beyond the tracheids of the veins. They give off short branches which 

 make contact with corresponding branches of the stellate parenchyma of 

 which the body of the petal is composed (see Text-figure 3). 



In petals rich in oxydase the stellate parenchyma cells, the branches 

 of which abut on those of the bundle sheath cells, also give oxydase 

 reactions, sometimes as marked but generally less marked than those of 

 the cells of the bundle sheath. The reaction in the cells of the stellate 

 parenchyma becomes more faint as the cells of that tissue are traced 

 further from the veins (see Text-figure 3). 



The appearance presented by the stellate parenchyma and the 

 bundle sheath is as though oxydase were passing from the cells of the 

 latter to those of the former. 



We have given reason in a former communication (Keeble and 

 Armstrong, 1912 b) for our belief that oxydase may be translated from 

 cell to cell, and have offered the suggestion that the frequency with 



