126 Chemistry of MendeUan Factors for Floiver-Colour 



analyses of both artificial and natural antliocyauin from the same plant 

 can provide evidence which is of value. 



CONCLU.SIONS. 



1. There arc three varieties of Antirrhinum majus, ivory, yellow 

 and white which do not form anthocyanin. Ivory is dominant to yellow 

 and contains a factor "/" which is absent from yellow. 



2. It has been shown that the pigments in the ivory and yellow 

 varieties are flavones. Ivory contains a pale yellow flavone, apigenin, 

 and yellow, in addition to apigenin, a deeper yellow Havone, luteolin. 

 Hence the "/ " factor may be represented as the power to inhibit the 

 formation of luteolin. 



8. The white variety contains no flavone. 



4. When either the yellow or ivory is crossed with a white of 

 suitable composition, an F^ containing anthocyanin is produced. There- 

 fore it appears likely that the anthocyanin is formed from a flavone by 

 the action of some factor contained in the white. 



5. It has been suggested that anthocyanin is either an oxidation 

 or a condensation product of a flavone or both. 



6. Two anthocyanins have been isolated from Antirrhinum, red 

 and magenta, the latter containing a "B" factor which is absent from 

 the red. 



7. Anal3'ses of the red and magenta pigments have shown that 

 they both contain a higher percentage of oxygen than the flavones. 

 Also, magenta has a higher percentage of oxygen than red. 



8. Determinations of the molecular weights of the red and magenta 

 pigments indicate that the anthocyanin molecules are at least twice or 

 three times as large as the flavones. Hence, in addition to oxidation, 

 condensation must have taken place, either between flavone molecules, 

 or between the flavone and .some other aromatic substance. In the 

 latter case, one substance, the " R " factor, may give red anthocyanin 

 and a second substance, the "B" factor, magenta. 



9. The view that anthocyanin is in part, at anj^ rate, an oxidation 

 product is confirmed by the researches of Keeble, Armstrong and Jones, 

 who have shown that anthocyanin is formed in tissues most rich in 

 oxidising enzymes, though there is no good evidence, from the well- 

 known Mendelian cases, of albinism being due to loss of an oxidising 

 enzyme. 



