and fibers, whose secondary walls have been reduced to 
granular residues. The secondary wall residues and other 
degraded or ‘‘humified’’ decomposition products are 
readily extracted (with little or no deleterious action on 
the remaining cellulose) by means of various techniques 
utilizing sodium chlorite as the delignifying agent 
(Barghoorn, 1948). 
Studies of fibrous peats of varying post-glacial age 
consistently show a cellulosic residue, often representing 
avery small fraction of the original sample. The amount 
of cellulose recovered is much influenced by the tech- 
nique employed in lignin extraction; direct repeated 
chlorination or treatment with acidified hypochlorite so- 
lutions may result in oxidation and partial (or complete) 
solution of the persisting degraded cellulose residues. 
Anatomically, however, structural cellulosic residues pre- 
served in peats consist for the most part of thick, previously 
unlignified primary cell walls. Tissues possessing thick, 
lignified secondary cell walls may undergo extensive de- 
gradation in environments in which even delicate cellu- 
losic cell walls are incompletely broken down. In recog- 
nition of these facts it seems a paradox of note that the 
most delicate tissues of various plant organs may be far 
more resistant to anaerobic degradation than are cells or 
tissues possessing thick, frequently heavily lignified sec- 
ondary cell walls. 
In view of these observations, which are consistently 
supported by anatomical studies as well as by chemical 
analyses of degraded plant remains, it seems quite diffi- 
cult to interpret selective degradation of different por- 
tions of the plant cell wall except in terms of chemical 
differences in the successively formed lamellae of the cell 
wall. In other words, the ewceptional resistance of the 
primary cell wall to degradation may be due to chemical 
rather than physical ‘‘protective’’ factors. Such an inter- 
[ 14 ] 
