A GENETICO-rHYSIOLOOICAL STUDY ON" THE l(iH>rAnnN ETC. 



23 



The skiu of the youug, gi'ceu gi'iipas was füund to Ije very rich iu the 

 chromogeuic siiljstjiuce P l>iit it coutuius ouh' u ti-aco of the chruiiKjgeuic 

 siibstiince F. It is of interest to find that the "white" varieties, so far 

 examinetl, coutaiuetl the clu'omogenic substance as luiich as that showii by 

 the coloured varieties. Eveu in the deep Ijlack variet}-, the reduoticui colour 

 of the extract of the green skiu was only faint, so it seems highly probal)le 

 that the authocymiin pigment in the skiu of the gi-ape may lie formed chiefly 

 from the chixjmogenic substance P rather than the clu'omogenic substance F. 

 According to WillstXtter aud ZollesTiER (191.5)' the anthocyanin of gi-ape 

 skiu (North Itnliau or hothouse) were seuidin .tud PPuiu which are the methyl 

 ethere of dclphiuidin and delphiuiu l•os^5ectivol^■. The chemical investigation 

 of the chi-omogenic substances iu the gi-ape skiu is inviting, for it may cleai" 

 the relation of anthocyanin to the clu'omogenic substances P aud F. 



Dezani found two kinds of the clu'omogeuic substances in the white grapas 

 of which one only is precipitixted Ijy lead acetate. By the action of hydro- 

 chloric acid, coloming matters are obtained which are analogous to the ajuocy- 

 anius. The conversion of these substances into colouring matter is due not 

 to oxidatiou, but probably to hydrolytic scission ■\\ith simultanious formation 

 of a reducing substance. In the residue fi'om the clu-omogeuic sulistauces there 

 are other substances which give a red colour with alkali. The result obtained 

 by BteDRiCK and Anthony'' shows that (1) " wliite " is a pure, colour, namely 

 "white" X "white" gives ouly "white": and (2) "white" is recessive to 

 both Ijlack aud red. 



Table 12. 



Chromogen content of the sldn of green gmiies. 



1. AVrLLSTÄTTEii, E. anl Zollinger, E. H., Ueber die Farbstoffe der Weintraube u. der 

 Heiderbeere. Liebig. 408:83, 1915, and 412:195, 1916. See also Dezani, S.. loc. cit. 



2. Hedeick, U. p. and Anthont, K. D., Inheritance of Certain Characters of Grapes. N. Y. 

 Agric. Exp. Station. Technical Bidl. 45. 1915, pp. 19. 



