Varietäten, Descendenz, Hybriden. 9 



connection between the genetic behaviour of the pigments and their 

 chemical reactions and Constitution. 



The pigments dealt with fall into two groups: 



A. Pigments soluble in the cell sap. These are subdivided again 

 into 1. soluble red-purple-blue pigments known as "anthocyanin"; 

 and 2. soluble yellow pigments known as "xanthein". 



B. Pigments associated with chromoplastids, the colours ranging 

 from orange-red to yellow. This group includes the two well-known 

 pigments Carotin and Xanthin. 



The author shows that under the term "Anthocyanin" are in- 

 cluded several pigments which differ from one another as regards 

 their inheritance, the colours to which they give rise in Variation, 

 and their behaviour towards chemical reagents. 



The colours of the varieties arising from an anthocyanic type 

 may be regarded as components of the original anthocyanin; the 

 type, conversely, may be supposed to lose its components (which 

 are expressible as Mendelian factors) in succession, thus giving rise 

 to a series of colour variations. 



From a consideration of the ränge of colour found in various 

 species possessing anthocyanin and from the results of breeding 

 experiments, the author concludes that there are two classes of 

 anthocyanin which differ in regard to the series of varieties to 

 which each can give rise. In the one case the decomposition gives 

 rise to a xantheic yellow derivative, as for example in Antirrhinum 

 maj'us; in the other case no such xantheic derivative is formed and con- 

 sequently no yellow variety exists, as for example in Lathyrus odoratus. 



The close relation between the xantheic pigments, the glucoside- 

 like bodies from which they are perhaps derived and the anthocyanin 

 of which these bodies are possibly constituents, is suggested by the 

 fact that yellow xantheic varieties almost always have an antho- 

 cyanic type. This point is well exemplified in the Compositae, where 

 (disregarding the plastid pigments which are usually present in 

 addition to the sap colours) the yellow varieties of Coreopsis, Chrys- 

 anthemum carinatum, Dahlia variabilis , Helichrysum bracteatum 

 contain xanthein, while the type has anthocyanin; other genera 

 such as Zinnia elegans, Gaillardia, Hierachim rubrum, have antho- 

 cyanin of the kind which gives no xantheic derivatives. 



The author classifies the anthocyanins as 1. a purple antho- 

 cyanin, 2. a purplish-red anthocyanin, and 3. a red anthocyanin; 

 each kind being characterised by specific chemical reactions. The 

 author mentions several species in which each of these types of 

 colour is exemplified; thus the -purple anthocyanin occurs, among 

 other cases, in the blue-purples of Lathyrus, the purplish-red in the 

 magentas and blue-reds of Antirrhinum and Lathyrus, the red in the 

 "rose doree" of Antirrhinum from which blueness is practically 

 absent. In the reds of Antirrhinum and the salmon-rose of Phlox 

 the deeper shades are dominant to the lighter shades, while in the 

 purples, purple-reds and magentas of Lathyrus, Matthiola, Phlox 

 and Antirrhinum the paler shades are dominant to the darker. All 

 these red pigments are alike in their reactions to strong sulphuric 

 acid and to alkalies, but the scarlet pigment of Lobelia cardinalis 

 and Phaseolus multiflorus is of a different kind , while it appears 

 that the red pigments of the Papaveraceae differ again. The red 

 pigments of the allied Orders Amarantaceae, Nyctaginaceae, Phyto- 

 laccaceae, and Portulacaceae form an isolated group giving reactions 

 essentially different from those mentioned above. 



