404 P- Q- 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 climate, 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 m 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 



