470 M. Wheldale. 



In ail probability, the explanation of this anomaly lies in the 

 dual nature of oxydases, in that they consist, as we have seen, of 

 oxygenase and Peroxydase. If we suppose the plant to lose the 

 oxygenase activity apart from the Peroxydase, then two kinds of 

 albinism would result; in one the Peroxydase link is missing from 

 the mechanism for carrying oxygen to the chromogen; in the other 

 the oxygenase element. In neither case can there be any development 

 of anthocyanin, but on mating of two such albinos, the mechanism is 

 again complete and pigment formation becomes possible. 



We can still further extend this idea of the independent in- 

 heritance of the two components of an oxidising enzyme in connection 

 with the colour genetics of Stocks.') The action of the red oxydase 

 alone, as previously stated, produces a true red variety. But it is 

 quite conceivable that the oxygenase half of the blueing oxydase may 

 operate in conjunction with the reddening oxydase, thereby giving 

 rise to a bluish-red variety intermediate between the true red variety 

 and the purple type; on similar lines, the blueing Peroxydase may 

 work together with the reddening oxydase and this combination 

 would account for the existence of a second, slightly different, bluish- 

 red variety. Finally, when both reddening and blueing ferments are 

 intact in the plant, we arrive at the purple type. In this way we 

 can represent both in terms of Mendelian factors and in terms of 

 oxydases the series of genetically distinct varieties which actually 

 exist, ranging as they do from true I'ed, through bluish-red to the 

 purple of the tj^pe. 



The foregoing representation of Mendelian factors in terms of 

 oxydases is not purely speculative. Experimentally the petals of 

 Sweet Pea and Stock plants of known pedigree have been found to 

 vary with respect to their oxidative powers on guaiacum. It is 

 evident that the loss of either element, oxygenase or Peroxydase, 

 from the initial reddening factor will give rise to albinism even though 

 the albino may carry blueing or other modifying factors. Hence in 

 any genus having a complex series of colour varieties, there are a 

 number of possible albinos, both genetically and physiologically 

 different from each other. By selection we are able to procure an 

 albino carrying any particular factor and it is to a large extent the 

 behaviour of these extracted albinos toward guaiacum which has led 

 me to infer that there is a definite connection between Mendelian 

 colour factors and oxidising enzymes. 



M Saunders, Reports to Evolution Comm. Eoy. Soc, I, II, III, IV. 



