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 couutry. 



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 bSte 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 is 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.e. 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 



