Miss Wheldale, On the nature of anihocyanin. 159 



colouration. It is probable that magenta and crimson are different 

 pigments arising from the action of the same oxydase upon 

 different chromogens. 



Hence we see that in Antirrhinum three non-anthocyanic 

 varieties exist. Ivory is a 'white' carrying the chromogen giving 

 rise to magenta; yellow is a ' white ' carrying the chromogen giving 

 rise to crimson in oxidation and the true albino contains no 

 chromogen but probably only the oxydase. 



There is some resemblance between Antirrhinum and Primula 

 in that one can detect in the latter two kinds of whites carrying 

 chromogens giving rise to magenta and crimson respectively but 

 the albino containing no chromogen has so far not been identified 

 in Primula and may not exist. 



There is moreover a further resemblance as regards the blueing 

 factor; in both Antirrhinum and Primula the crimsons and 

 magentas are of the purplish-red form of anthocyanin. When the 

 blueing factor is absent, varieties arise containing red anthocyanin*. 

 In Antirrhinum these are the 'rose doree' (from magenta) and 

 'bronze' (from crimson). Similarly in Primula, loss of the blueing 

 factor gives rise to 'pink' (from magenta) and 'orange king' (from 

 crimson). 



It is conceivable that the green-stemmed variety of Primula 

 may represent, in particular so to speak, a class of plants in general 

 which do not contain the requisite oxydase and hence can never 

 produce red pigment. Galanthus nivalis, Narcissus poeticus, 

 Gucurbita Pepo, Helianthus annuus and numerous others would 

 be included in this class. 



The red-stemmed white, on the contrary, may be the repre- 

 sentative of a class of plants which are anthocyanic but in the 

 flowers of which an inhibitor is present. Such plants have white 

 or nearly white flowers, though the stems and foliage may contain 

 more or less anthocyanin. Some marked examples of this class 

 would be Oxalis acetosella, Geranium Robertianum var. album, 

 white cultivated Cyclamen persicum, Crataegus oxyacantha, Rosa 

 arvensis, Nymphaea alba, Angelica Sylvestris, and many other 

 Umbelliferae. 



Loss of the inhibiting factor from this latter class would give 

 rise to a fully coloured variety from the white-flowered type, the 

 exact converse of the origin of a true albino from a coloured type. 

 Such cases are rather rare. The most striking examples are the 

 origin under cultivation of the deep red and magenta and of the 

 pink varieties from the original white-flowered Cyclamen persicum 

 which has red stems and leaves. The origin of the tinted Primula 

 acaulis from the wild type which has anthocyanin in its petioles 

 and leaf-stalks only. 



* Wheldale 20. 



