1908.] 



Flowers with Special Reference to Genetics. 



49 



type, purplish-red anthoeyanin is the ultimate form. The red of Antirrhinum 

 is represented by the " rose doree " type, which finds its parallel in the flesh 

 and copper of Matthiola, certain scarlets of Zathyrus, and the salmon-rose of 

 Phlox Drummondii. 



It is of interest to note also that in the reds of Antirrhinum and the 

 .salmon-rose of Phlox* of which several shades exist, the deeper are dominant 

 to the paler, while in the purples, purple-reds, and magentas of Zathyrus 

 Matthiola, Phlox, and Antirrhinum, the paler shades are dominant to the 

 deeper. As regards shades of one colour, a fuller investigation has been 

 made in Antirrhinum, in which genus every shade is a definite zygotic form, 

 and the chemical reactions of these shades are fundamentally similar though 

 differing in degree. The precipitates with basic lead acetate, for instance, 

 are of varying shades of green, yet these remain unaltered on artificial 

 concentration or dilution of the extract. This would appear to indicate that 

 the shade of colour was but an outward indication of some definite organic 

 compound in the sap. 



All the red pigments so far described give, with strong sulphuric acidj 

 bright red and yellow colours, becoming orange when mixed ; it seems 

 possible that the red is due to the reddening factor, and the yellow to the 

 glucoside-like constituent of the anthoeyanin. With alkalis, the reddening 

 factor of the bluish-red turns blue and the other body yellow, the result 

 being green, sometimes rapidly fading to yellow. Basic lead acetate gives 

 blue-green or green precipitates, due again to the same mixture. 



The scarlet pigment of some genera — Zobelia, cardinalis, Phaseolus riiulti- 

 Jloms — is again different, in that it gives a bluish colour with alkalis and 

 a red precipitate with basic lead acetate. 



With regard to natural orders and relationships, as far as these investiga- 

 tions have gone, it appears that the red pigments of the Papaveracece differ 

 from others. Also those of the allied orders Amarantcvcem, Nycta.ginacea}, 

 Phytolaccacece, and Portulacaxece (included in the Centrospermai by Engler), 

 form an isolated group giving reactions essentially different from any hitherto 

 described. 



Of the Papaveraceas, the red pigment of Glaucium phoeniccum and Papaver 

 Phceas gives a purple colour with basic lead acetate. 



The red pigment of Amaranthus (and other genera of the same order 

 according to Weigert(ll)) is characterised by its insolubihty in alcohol. 

 With concentrated sulphuric acid it gives a purple colour, with ammonia 



* I am indebted to Miss Killby for this information. 



t Reactions are best seen by dropping acid on to the pigment on a white porcelain 

 plate. Mixtures of colours are thus more readily detected than in bulk in solution. 

 VOL. LXXXI. — B. t E 



