1899] CHEMISTRY OF OUR FOREST TREES 59 



of beautiful anhydrides, which never reach the humus-like, dull, dirty- 

 browns yielded by other tannins. The most striking constituent is the 

 highly fluorescent aesculin described by Martins and St. George in 1818 ; 

 it is related to the fraxin of the Ash, and this latter is also' contained in 

 the tree under review. In the bark a fluid oil, phlobaphene, and very 

 small quantities of aesculetin and its hydrate, are also found. The 

 leaves are eminent for their richness in carotin in early June, their 

 abundance of queraescitrin (glucoside of quercetin), fat, wax, phloba- 

 phene, and resin, and much tannin in autumn. The seed contains 

 about 4 per cent fatty oil and 14 per cent starch, also fruit sugar, and 

 a series of curious glucosides and bitter principles representative of 

 proteid disorganisation. It is rather a remarkable feature that this tree 

 and its allies exhibit very slight indications of the presence or decom- 

 position products of gum, mucilage, etc. ; they are all starch-producing 

 trees, but apparently there is no superfluity, waste, or prodigality of 

 this substance, and at the same time, and especially in some of the 

 maples, there is an abundant deposition of waxy matters, and of silice- 

 ous incrustations. It is quite possible that some of the foreign species 

 of Sapindaceae unknown to me may be practically fat-trees. On the 

 whole, this order is extremely interesting ; and coming away fresh from 

 its analysis, we are impressed with the struggle, as it were, between 

 the starch and the fat — the sugar rising into a supremacy, culminating 

 in A. saccharinum, and with the lavish abundance and superb beauty 

 of the products of de-assimilation. 



One more tree remains to be noticed, viz. the Linden (Tilia euro- 

 paca), which possesses morphological and chemical characters of extra- 

 ordinary interest. It is the most pronounced fat-producing member of 

 our woods. Its seeds contain no starch, and very little carbohydrate, 

 but store up 5 8 per cent of a bright yellow non-drying oil. The wood 

 seems to have some difficulty in parting with its reserves of fat, which 

 remain, especially in the older rings, up till June or later, and the 

 starch that creeps into its place begins to dissolve early in the autumn, 

 none whatever remaining in the pith, wood, or bark during the winter. 

 A special peculiarity of the tissues is the inconvenient abundance of 

 mucilage both in the intercellular spaces of the parenchyma of the 

 primary cortex and in the epidermis of the leaves. The large and very 

 conspicuous sieve-tubes of the inner bast contain very thick, mucilagin- 

 ous masses of albuminoid matters, but no starch. The amount of 

 mineral matters in the leaves is very great, and in autumn they are 

 incrusted with silica. On the whole this tree exhibits, except as regards 

 starch, a very considerable energy of assimilation ; and if some of its 

 outcome tends towards decomposition or degradation, the proportion of 

 the higher products of de-assimilation is decidedly not relatively high ; 

 in fact, those which depend on the destructive metabolism of starch 

 are, under ordinary conditions, markedly absent. 



Pattekdale, Westmorland. 



