F. Kbbblb and E. F. Armstrong 



297 



which lines of colour are seen to demark the veins of petals is 

 attributable to the action of oxydases which pass from the bundle to 

 the epidermis. 



Fig. 3. The oxydase content of tlie cells of the bundle sheath of the terminal portions 

 of a vein in a petal of P. sinensis. 



b.s. Bundle sheath — rich in oxydase. 



s.p. Stellate parenchyma, the cells in contact with those of the bundle sheath 



are rich in oxydase : those more distant contain less. 

 ()•- Tracheid. 

 i.c.s. Intercellular spaces. 



If preparations of sections treated with the benzidine reagent are 

 examined microscopically, the localisation of the brown product of 

 oxydase action may be seen in the cytoplasm of the tissues rich in 



