1899] CHEMISTRY OF OUR FOREST TREES 55 
closely related in systematic affinity are anything but very closely 
related as respects their physiological faculties, the sweep and potency 
of their vital energies, inasmuch as we can now attest and demonstrate 
that the inevitable chemical products thereof are, in the two cases, 
mightily different in quality and quantity. Bonnier has remarked that 
“the anatomical structure of a plant cannot always be deduced from 
its physiological functions; two plants, for instance, having similar 
chlorophyllous tissues may have very different powers of assimilation, 
and plants are known which have a palisade tissue more developed 
than others, but which, nevertheless, possess much feebler chlorophyllian 
functions.” But where morphology fails, chemistry braces up in aid; 
and yet with all its magnificent powers and abundant resources it does 
not presume to be able to explain why or how it happens that one or 
two of our heath and forest species of the extensive order Amentaceae 
should be pre-eminent producers of fatty matters, leaving the rest 
shivering, as it were, in the cold of a lavish receipt and a thrifty 
expenditure of carbohydrates. I will now briefly pass in review the 
principal chemical features and characteristics of the dicotyledonous 
forest flora of our country. 
The various species of Elm (e.g., Ulmus campestris and montana and 
their varieties), in conformity with their lowly systematic affinities, 
exhibit nothing very advanced or developed, but rather a kind of 
degradation in the direction of a very facile production of that béte noire 
of the plant analyst known as vegetable mucilage. In the cortex 
special sacs evolved from the meristem, and due to a destruction of 
living cells with formation of cavities or canals, contain mucilage in 
large quantity ; it is a pectosic mucilage with acidic function, being 
coloured by basic dyes; it swells up and almost wholly dissolves in 
water, but 1s not derived from cellulose. Some resin occurs in elm bark 
and wood parenchyma, but the quantity of tannin, phloroglucin, etc., is 
decidedly scanty in all parts. The leaves contain much carotin, con- 
siderable wax, and a little fat, and their starch-producing power is 
undoubtedly vigorous. In fact, the Elm is a very distinctive and 
decisive starch-tree, exhibiting a protoplasmic concentration rather 
uncommon; the lavish fortification of its bark and leaves with lime 
and silica, and the ability of some of its varieties to form a primary, 
persistent periderm, though only feebly suberified, are features clearly 
suggestive of the special quality of its activities. 
Passing on now to these interesting morphologically allied congeners 
the Birch and the Alder, we realise in a striking degree the supreme 
value of chemical analysis in its application to botanical science. 
These two species are closely related taxonomically, and yet when 
chemically investigated we almost immediately discern very serious 
differences in respect to physiology. Both are fat-trees, i.c. during the 
winter no starch is found in the pith, wood, or bark, or in other words, 
their leaves are incapable of producing much starch, and the amylaceous 
