128 
Potter. — On the Occurrence of Cellulose in the 
a variety of trees in all situations, probably representing a stage of arrested 
development. As this fact has not hitherto been recognized the observation 
is important, and has some bearing upon the study of fungoid action 
in timber. 
It is well known that boiling water has a destroying and dissolving 
action upon the cell-wall. As long ago as 1882 Singer (’ 82 ) has shown 
that four substances can be extracted from xylem by boiling water, namely, 
vanilin ; a substance which shows the reactions of coniferin ; a gum, 
which is soluble in water ; and a substance soluble in water not identical 
with the other three ; these all entering into the composition of what is 
known as lignin, though in what relationship is not determined. 
Recently, Van Wisselingh (’ 98 ) has shown that by heating sections 
of the root of Beta vulgaris for six hours in distilled water, at a temperature 
of about I25°C., a pure cellulose wall remains behind, and the pectin 
substances are destroyed and removed. It seems probable that the 
operation of sterilizing by discontinuous boiling would have some such 
effect upon the lignified walls, and that some substances might be destroyed 
or removed from the cellulose matrix during the process ; in other words 
it would have a delignifying action. 
The wood of Fraxinus affords very suitable material for studying the 
action of boiling water upon the xylem ; since, as far as I have been able to 
determine from the examination of numerous sections taken from various 
trees, no broad inner lining of cellulose is present in the fibres. The xylem 
appears to undergo complete lignification. Transverse sections were taken 
from a stem ten years old and about 2-4 cm. in diameter, and some of these 
were examined at once with chlor-zinc-iodine. Fig. 5 is a good illustration 
of the appearance presented, the walls are thick and hard and show no 
trace of violet colour, the only effect of the chlor-zinc-iodine being to turn 
the walls yellow. The other sections were placed in a boiling tube half 
filled with water and steamed for about two hours on consecutive days, 
remaining immersed in water the whole time. Some of these sections were 
removed at intervals and subjected to treatment with chlor-zinc-iodine. 
After two days some delignification was slightly indicated ; after three 
days it was well pronounced. Fig. 6 represents the general appearance 
after four days: the middle lamella is a bright yellow, while the inner 
layers of the fibre-walls are swollen and stained violet, more deeply on 
the inner surface and shading away towards the middle lamella, showing 
almost complete delignification. A comparison of the sections before and 
after boiling represented in Fig. 5 and Fig. 6 shows in a most marked manner 
the delignifying action of the boiling water. It should be noted that in 
the sections steamed four times a delignification had already commenced in 
some of the wood-vessels. 
