282 



BIOCHEMICAL SYSTEMATICS 



OH 



I R = CHoOH: 



dehydro- 



diconiferyl- 



alcohol 



OCH, 



H3CO 



HC CH2 

 



OCH, 



OH 



II d, 2-plno- 

 resinol 



HoCOH 

 HC 



HCOH 



IV R = CHO 

 dehydrodiconlferylaldehyd 



OCH, 



OCH3 



OH 



III guaiacyl- 



glycerln- 

 coniferylether 



Fig. 14-2. Four lignin type dimers, formed enzymatically, which 

 represent possible Hnkages of monomers in true hgnin. (Freuden- 

 berg, 1959). 



variation cannot be established without further technical advances in 

 the degradation of lignin. 



There is evidence that lignin varies even within a single plant. 

 Manskaja (1959) reported that the younger parts of a plant may pro- 

 duce lignin with a lower methoxy content than that of the mature 

 tissue, and Wardrop and Bland (1959) have discussed a similar situa- 

 tion in the genera Eucalyptus and Tilia. Since higher methoxy content 

 is associated with a higher syringyl-guaiacyl ratio, and the higher 



