54 P.O: KEEGAN [sULY 
which split asunder internally, leaving a hollow space (resin-passage) 
into which there flows the product of their spent and exhausted labour 
(destructive metabolism), viz. the resin. Physiological operations of 
this very pronounced and particular nature are rather rare in the woody 
tissues of the stem and root of our Dicotyledons. Then again, we can 
attest the curious transformations which the starch, fatty, and resinous 
constituents of the wood of the Scotch Fir undergo at the different 
seasons of the year. According to Fischer there is no starch at all in 
the wood, pith, or bark during the winter; and Jonssen asserts that at 
this season the wood is entirely devoid of starch in all parts, but bears 
a considerable quantity of fat-oil, finely distributed, which disappears 
in April, while during the summer the wood is very poor in fatty 
matter. The needle-shaped evergreen leaves, again, are divested of 
starch in winter; but about the 1st April, even while the chlorophyll 
is still in the wintry condition, and although a low temperature and no 
special sunlight may occur, these organs are found crammed full of 
starch. So that here a very remarkable phenomenon is presented, viz. 
a plenteous production of starch following quickly on the winter sleep, 
and under conditions the very reverse of those which, in most of the 
dicotyledons of our latitudes, are indispensable for accomplishing a 
precisely similar effect. In fact, certain still undetermined causes, 
operative after a kind of pre-ordained periodicity, seem to dominate the 
physiological action of the protoplasm of these extraordinary foliar 
organs. Coniferous leaves are always much poorer in nitrogenous and 
in mineral constituents (ash) than those of deciduous trees, and the ash 
generally contains larger amounts of magnesia, iron, and silica. On 
the whole, it may be concluded, from a study of the character and 
quantity of the chemical constituents, that the coniferous Gymnosperms 
are subject to a fitful periodicity of physiological energy, interrupted 
by corresponding and longer periods of repose akin to hibernation, which 
permit of extensive accumulation of “dry substance” in the tissues 
under the form, more especially of the products of de-assimilation 
(tannoids, tannins, glucosides (coniferin), resins, waxes, and volatile 
oil), while on the other hand the products of assimilation (starch, 
fat-oil, and nitrogen-compounds) are relatively and absolutely scanty. 
Reviewing now the more extensive and familiar field of the Dicoty- 
ledons, we are impressed not only by the comparative chemical similarity 
of certain of the woodland organisms, but also by the fact that a few 
other groups stand forth singly and, as it were, with an isolated 
heterogeneity as remarkable as it is apparently inexplicable. Peering 
adown the wondrous vistas opened out to us by the resources and - 
appliances of chemistry, the squabbles of the “ splitters ” and “ lumpers ” 
of the would-be systematic taxonomists seem fantastic and puerile; the 
hair-splitting agreements or otherwise in the essential or unessential 
superficial characters of the organs of reproduction, etc., are liable to be 
contemned or wholly ignored. We find that species of trees very 
