216 Prof. F. Keeble and Dr. E. F. Armstrong. [Mar. 15, 



peroxydases in P. sinensis. One, the " epidermal " peroxydase, occurs in the 

 epidermis and in some cases in the layers subjacent to the epidermis. 

 Another, the " bundle " peroxydase, is localised in layers of cells neighbour- 

 ing the woody tissues of the vascular bundles. 



Both epidermal and bundle peroxydases occur in the vegetative parts of the 

 plant as well as in the flower. In the stem the epidermal peroxydase is 

 separated widely from the bundle peroxydase by many layers of cortical cells, 

 which in many varieties at all events contain no peroxydase ; but in the 

 tenuous petals of the flower the bundle peroxydase occurs of necessity in 

 close proximity with the epidermal peroxydase. 



4. Certain varieties of P. sinensis such as Crimson King, Coral Pink, and 

 Sirdar give, under certain circumstances, a direct oxydase reaction : that is 

 a characteristic coloration is produced when they are treated with the 

 oxydase reagent alone. 



5. The bundle peroxydase of the petals of the flower of P. sinensis is 

 located in the cells of the bundle sheath which surrounds the veins. The 

 peroxydase accompanies that sheath throughout the repeated ramification of 

 the veins, and may be seen in microscopic preparations to extend to the tips 

 of their finest branches ; the epidermal peroxydase occurs in the superficial 

 papillate cells of the petals. 



6. Where, as is the case with many varieties of P. sinensis, the flower has 

 a yellow eye, no epidermal peroxydase is demonstrable over the eye except in 

 the hairs which are produced as outgrowths from the epidermis. 



7. The epidermal and bundle peroxydases differ from one another both in 

 their distribution and in their colour reactions. Thus bundle peroxydase 

 reacts with a-naphthol and hydrogen peroxide to yield a lavender-blue 

 colour which picks out the veins in exquisite detail. With this reagent the 

 epidermal peroxydase yields generally no colour reaction. 



Selective coloration in the opposite sense though less precise is produced 

 by the addition of benzidine and hydrogen peroxide to the flower. Treat- 

 ment with an alcoholic solution of benzidine brings about first decolorisation 

 of the sap (anthocyan) pigments of shoot and flower. The subsequent addition 

 of hydrogen peroxide activates both epidermal and bundle peroxydases and 

 results in a rich brown uniform coloration of the surface layer of the petals, 

 which coloration extends also to the veins. 



8. White flowers which by breeding tests are known to be dominant 

 whites fail to give the epidermal peroxydase reaction ; but in such flowers 

 a faint bundle peroxydase reaction may occur. 



Both epidermal and bundle peroxydases are, however, present in dominant 

 white flowers ; for if such flowers are treated with hydrogen cyanide and 



