29-2 



Oxydases and Pigments of Plants 



in flakes or spots, are very common among cultivated plants, for example. 

 Azaleas, Sweet Williams, Stocks and Carnations. They are known as 

 evei'-sporting and their genetieal behaviour is difficult of interpretation. 

 The observations of which we have just given a brief account indicate 

 quite definitely that in the case of the white magenta-flaked flowers of 

 Mt. Blanc Star the ever-sporting habit is associated with irregularities 

 in amount or activity of oxydase in the tissues of the petals. 



Fig. 1. The coincidence of peroxydase with pigment in the white magenta- flaked flower 

 of Mt. Blanc Star. Diagrammatic. The distribution of pigment in the several petals 

 was recorded with reference to the incision indicated at J) («). Petal A was uniformly 

 magenta coloured, B and C indicate the position of magenta flakes. The peroxydase 

 distribution is shown in fig. 6. The copious wound peroxydase is indicated by 

 the black patch, the position of which coincides with D which marks the place of the 

 wound. (See text and Text-figure 5.) 



Inasmuch as the problems presented by ever-sporting varieties are 

 of considerable interest, we have extended our inquiry with respect to 

 them to other species of plants. We were the more anxious to do so 

 because, except for the difiicult case of white magenta flaked varieties, 

 in which, as we have seen, the amount of oxydase-reaction is small, we 

 had discovered no race of P. sinensis the flowers of which lack oxydase. 

 Now as pointed out already, this fact, though it might be predicated 

 from our knowledge of the genetics of P. sinensis, is less likely to obtain 

 with respect to certain other plants. Thus, the genetieal behaviour of 

 Sweet Peas is such that two distinct factors for colour must be assumed 

 if this behaviour is to be accounted for in terms of Mendelian hypothesis. 

 Hence the suggestion is bound to present itself that the two factors in 

 question are an oxydase-producing and a chromogen-liberating factor. 

 We have therefore an added reason in seeking among plants other than 

 P. sinensis, for an example of a flower which lacks oxydase. 



