152 ANTHOCYANINS AND GENETICS 



We may next consider those variations which affect the intensity 

 of colour. If a colour series such as we have described for Lathy rus 

 or Antirrhinum be examined, a number of definite varieties will be 

 found of a paler or deeper shade of the same colour. Without Mendelian 

 analyses it is not as a rule possible to arrive at the underlying significance 

 of the shade differences. Thus, a paler shade than the type may signify 

 either loss of a factor for full-colour, or the existence of a heterozygous 

 form between type and albino. Hence, in dealing with this kind of 

 variation, we can only quote as satisfactory instances those cases of 

 which we have knowledge from experimental breeding. The main 

 expressions of intensity-variation are tinged and deep varieties. The 

 tinged variety forms a case in which a deepening, or full-colour factor, 

 affecting anthocyanin formation has disappeared from the type, leaving 

 the flower flushed or tinged with colour only. Examples are the 

 'tinged ivory' variety of Antirrhinum (Wheldale, 535) and the 'tinged 

 white' and 'picotee' of Laihyrus (Bateson & Punnett, 500). The 

 variation of tingeing is common to both red and blue classes. 



The deep variety can be defined as one having a deeper shade of 

 anthocyanin, i.e. more pigment, than the type from which it is derived, 

 as the result of the loss of an inhibiting factor. Since it is often difficult, 

 and sometimes impossible, to ascertain the original type in many horti- 

 cultural plants, this definition cannot be rigidly applied. Like tingeing, 

 the variation of deepening is common to both red and blue classes. 

 Examples of such varieties are the deep shades of magenta, crimson, 

 rose dore and bronze of Antirrhinum (Wheldale, 535, 548), purple- 

 winged 'Purple Invincible' and 'Miss Hunt' varieties of Laihyrus 

 odoratus (Bateson & Punnett, 500) ; deep shades of crimson and magenta 

 in Primula sinensis (Gregory, 557) and deep purple and crimson in 

 Matthiola (Saunders, 487) ; also deep varieties of Cyclamen. The 

 following species, among many others, have varieties obviously deeper 

 than the type : Althaea rosea, Dahlia variabilis, Dianthus Caryophyllus, 

 D. barbatus, Hyacinthus orientalis and Phlox Drummondii. 



In the instances quoted above, the type, from which the deeper 

 variety is derived, is itself fully pigmented. There are, however, other 

 cases in which the type is either unpigmented, or only slightly pigmented, 

 and, on the loss of an inhibiting factor, a coloured variety is produced. 

 As examples may be quoted Anemone japonica in which the type has 

 a white petal oid calyx tinged with anthocyanin on the under surface, 

 whereas the variety is purple-flowered ; the wild Bellis perennis (Daisy) 

 has white ray florets tinged with anthocyanin and the garden variety 



