468 • M. Wheldale. 



Examples of red varieties arising from a purple type are very 

 numerous. As illustrations may be quoted the 'reds' of Sweet Peas, 

 the 'Eose doré' of Antirrhiniim, the 'Orange King' of Primula sinensis, 

 the 'Salmon-Rose' of Phlox Drummondii, Dianthus barhatus and many 

 others. 



We find a comparable 'red' variation from a blue type in Centaurea, 

 Aster, Hyacintlms, Campanula, Delphinium, Salvia, etc. It is unnecessary 

 to give illustrations of the second class, for albinism is the most 

 frequent variation under cultivation. 



Before giving the interpretation of the Mendelian factors in 

 terms of oxydases, it will be advantageous to describe briefly the 

 chemical properties of anthocyanin. 



The Chemical Nature of Anthocyanin. 



It will generally be found that the alcoholic extract of an albino 

 and of the uncoloured parts of pigmented plants gives reactions 

 characteristic of a group of aromatic compounds known as the flavones. 

 The constitution of these bodies is such as to give great scope for 

 isomeric variety and though some flavones are common to many 

 species, others may be in themselves specific. Careful isolation and 

 analysis is necessary before we can formulate the constitution of the 

 flavone present in any species. One of the most characteristic 

 reactions of these substances is the immediate production of an 

 intense yellow colour when brought into contact with alkalis or 

 ammonia vapour. Hence the cell -sap of all unpigmented organs 

 becomes bright yellow in ammonia vapour; this reaction is very 

 readily demonstrated in the flowers of albinos or the white flowers 

 of pigmented species. 



With an extract of bluish-red, purple or blue anthocyanin, a 

 different set of reactions is obtained. Here the result is due to the 

 presence of two substances, the unaltered chromogen and its purple 

 or blue oxidised product. We may suppose the oxidised products 

 to differ from each other much in the same way that the initial 

 chromogens vary among themselves. The pigment closely resembles 

 the flavone in its general behaviour towards chemical reagents except 

 that the range of colour reactions is different. The oxidised product 

 gives a blue colour with alkalis, whereas the chromogen, as previously 

 stated, gives a yellow colour. The result, therefore, of alkali action 

 on the combination is green due to the mixture of yellow and blue. 



