404 PIO KEEGAN [DECEMBER 
analogy of the autumn manifestation of colorific effect investing the 
woodlands at a time when the assimilatory activity becomes dull and 
deadened, there is nothing unreasonable in the assumption that 
oxidising effects continue to be produced later on when only a feeble 
minimum of protoplasmic respiration remains as the last remnant of 
vitality. Even in dead leaves the glucose and other autoxidisable 
substances disappear, at least in part, as the result of the direct action 
of atmospheric oxygen. So that whether the process be regarded as 
either physiological or chemical or both combined, it would be absurd 
to imagine that a substance absorbing oxygen so readily as tannin does, 
can remain totally unaffected through fresh winds, sunny skies at 
times, and a small absolute content of aerial moisture. Judging from 
the analogy of the fruit, wherein tannin remains long and in some 
cases even is completely destroyed by oxidation, it would seem that the 
tannin of the winter boughs and leaves gradually becomes, as the 
season advances, more complex in composition, less easily crystallisable, 
and less soluble; possibly it takes up new carbon radicals, whereby, 
while retaining an analogous-chemical constitution, its reducing pro- 
perties are not diminished. 
It might be imagined that a property like wax-formation, suberifica- 
tion, etc., to which plants owe their great power of resistance to the 
effects of clmate, would, if not specially prominent, be at all events 
not altogether suspended during the winter months. It appears, 
however, that even in these respects the palsying, life-consuming 
influences of cold are not arrested. ‘“ The resin and wax metamorphosis 
are probably conditioned by a slackening of the cellular activity,” says 
Wigand. On the other hand, according to Uloth, who had carefully 
studied the wax-formation in Acer striatum and other trees, this process 
is not a physiological but rather a purely chemical one, requiring a 
peculiar condition of the cellulose, with the co-operation of light and of 
a certain high temperature, and hence takes place only during summer. 
“During the winter,” he states, “as is seen distinctly after the fall of 
the leaves, the wax-forming process stands still in order to begin anew 
with the second spring entirely in the same way as before.” This 
attestation is of some importance, inasmuch as it throws some light on 
the vexed question of the precise physiological character and position 
of a substance, the origin of which has proved rather a bugbear to all 
serious students of arboreal chemistry. My own impression is that 
wax, suberin, etc., represent the products of chemical decomposition 
(deassimilation) resulting from the specially vigorous and rapid 
activity of certain locally restricted non-sexual propagative cells, such, 
for instance, as compose the phellogen and the epidermis of young 
leaves ; and this being so, the fact that this unwonted energy is 
arrested in winter becomes easily explicable, and is by no means 
extraordinary. 
Not the least remarkable of the phenomena connected with the 
