1908.] Flowers with Special Reference to Genetics. 47 



and Bosa. It is probable that the inheritance of_ flower-colour will be found 

 to be similar in these genera. 



The inheritance of colour in Lathyrus and Matthiola (Bateson, Punnett and 

 Saunders (1)) differs from Antirrhinum, in that two factors (C and E) are 

 required to produce colour, and the loss of either gives a white containing 

 only a glucoside-like substance. An additional factor, B, gives the purple 

 varieties. 



A similar range of colour to that in Lathyrus, i.e., shades of blue or purple 

 and red, together with white, is shown by Campanula, Digitalis purpurea, 

 Iberis, Lobelia, Nemophila insignis, Pisum, and many others ; no xantheic 

 variety occurs in this series. 



It is evident, then, that there are two classes of anthocyanin as regards the 

 series of varieties to which each can give rise ; in one case the decomposition 

 possibly of the glucoside-like constituent gives a yellow xantheic form, and 

 in the other case no such decomposition is possible, and no yellow variety 

 exists. 



The close relationship between xantheic pigments, the glucoside-like bodies, 

 from which they may be derived, and the anthocyanin, of which these bodies 

 are themselves possibly constituents, is suggested also by the fact that yellow 

 xantheic varieties almost always have an anthocyanic type. This connection 

 is well exemplified among the genera of the Compositse. Usually plastic! 

 pigments in addition are present in this order, but these may be disregarded 

 for the moment. Yellow varieties of Coreopsis, Chrysanthemum carinatum, 

 Dahlia variabilis, Bleliehrysum bracteatum, contain xanthein, while the type 

 has anthocyanin ; other genera, Zinnia elegans, Gaillardia, Hieracium rubrum, 

 have anthocyanin of the kind which gives no xantheic varieties, while, 

 finally, Calendula officinalis, Helianthus annuus, Erigeron spp., and Senecio spp. 

 have no xanthein and no anthocyanin. 



When we consider the behaviour of anthocyanin towards such substances 

 as acids, alkalis, certain salts, etc., we find this term includes at least several 

 groups of pigments. Two classes have been described by Weigert (11), and 

 termed "weinrot" and "riibenrot" respectively. The former is soluble in both 

 alcohol and water, giving with basic lead acetate blue-grey or blue-green 

 precipitates, and with concentrated sulphuric acid a bright red colour. It is 

 found in the leaves of Vitis, Ampelopsis quinquefolia, Rhus typhina, Cornus 

 sanguinea, and others. The latter, riibenrot, Weigert found in leaves 

 of the Amarantaceos and Chenopodiacea? {Beta vulgaris, Iresine, Amaranthus, 

 Atriplex), and in fruits of Bhytolacca decandra. Though readily soluble in 

 water, the pigment is insoluble in alcohol ; with basic lead acetate it gives a 

 red precipitate, with sulphuric acid and with ammonia a deep violet, but with 



