RELATIONSHIPS 



299 



yielded amongst other substances both pyrogallol and catechol, 

 the same compounds as are obtained under similar circum- 

 stances from the catechol tannins. By examining the struc- 

 tural formula of either the flavonol quercetin (i.) or of the 

 corresponding anthocyanidin cyanidin (11.), it will be seen 

 that the formation of phloroglucinol and catechol is readily 

 accounted for by rupture of the molecules along the dotted 



line : — 



OH 

 O / 



-OH 



OH 



HO- 



HO— : 



OH 



OH 



OH 



II. 



whereby the left half of the molecule would give phloro- 

 glucin (hi), and the left half would account for the catechol 

 (IV.) :- 



OH 



—OH 



IV. 



According to the same author the mother substance of all 

 these compounds is diphenyl propane (v.) : — 



-CH2 . CHj . CHj — V 



V. 



which may also be written as under : — 



CH, 



and it will readily be understood how by introduction of 

 hydroxyl groups into positions 3', 4', 3, 5, 7, and 9 and slight 

 rearrangement, it should be possible to pass without much 

 difficulty from one compound to another. 



Other substances of significance in the plant world are 



