PART II 



ANTHOCYANINS AND GENETICS 



CLASSES OF VARIATION. 



As pointed out in Chapter n, practically all flowering plants produce 

 anthocyanin ; moreover, when this pigment is developed in the flower, 

 we are able to see that each specific type forms anthocyanin of a certain 

 characteristic colour. In nature to some extent, but under cultivation 

 very commonly, colour- varieties arise from the type. The underlying 

 cause of these variations is still a matter for conjecture, though such 

 suggestions as can be offered will be given later. Colour- varieties 

 have afforded plentiful material for Mendelian research, and it is to 

 the cases of inheritance involving anthocyanin as a character that the 

 following pages are devoted. 



Among the colour-varieties of different genera and species, there 

 is a certain correspondence in the series of varieties produced, that is, 

 we may find one series in a number of plants not necessarily related, 

 and another series in a number of other plants, and so forth. The 

 kinds of variation which may occur we are able to classify as follows: 



1. The loss of power to form anthocyanin pigments which results 

 in albinism. The albino may be white or yellow ; if yellow, the pigment 

 may be either plastid or soluble. 



2. The loss of power to produce blueness. The type has blue, or 

 purple, anthocyanin : the variety has red anthocyanin . 



3. The loss of power to produce redness. The type has red antho- 

 cyanin : the variety blue, or purple, anthocyanin. 



4. The loss of power to augment the formation of anthocyanin 

 and hence to intensify its colour. The type is fully coloured: the 

 variety tinged only. 



5. The loss of power to inhibit the formation of anthocyanin and 

 hence to diminish its intensity. The type may be pale in colour and 

 the variety deep: or the type may be tinged only and the variety 

 fully coloured. 



The following variations are independent of variation in the 



w. P. 10 



