BOTANICAL AND CHEMICAL CHARACTKRS OF EUCALYPTS. 99 



Directing Influences of Inorganic Chemical Constituents. 



The V617 large Eucalyptus trees of Australia belong to groups the 

 species of which have much in common, both in botanical features and 

 chemical characters. Four of the trees of largest dimensions, gix>wing in 

 Eastern Austi-alia, are E. regnans, E. Delegatensis, E. obliqua' and E. 

 pilularis ; the first three are common both to Australia and Tasmania. 

 The bark of all these is more or less of a ' stringy ' nature in cases in 

 which it persists but the trees are mostly ' half-barked, ' the upper 

 portions being smooth, hence in some respects they appear to be 

 associated with the true ' Stringy barks,' E. eugenioides, E. macror- 

 rhyncha, &c., as well as with the class known as ' Gums.' The 

 anthers of these big trees are kidney-shaped (Renantherse) ; they all 

 have the leaf-venation indicative of phellandrene, which constituent they 

 all contain in smaller or greater amount ; the cotyledons of the seedlings 

 are all similar in shape. The large ti'ees mostly grow in soil com- 

 paratively poor in mineral constituents, the soil being of a siliceous 

 nature. The apparent difficulty of trees so placed is overcome, as they 

 have the peculiarity of only storing minute quantities of mineral con- 

 stituents in their timber (3) ; this appears to be one of the chief reasons 

 why such trees are able to continue growing until they reach very great 

 dimensions: E. regnans, for instance, sometimes exceeds 70 feet in 

 circumfei'ence and reaches a height of over 300 feet. If species grow- 

 ing in highly siliceous country stored mineral matter in the woody 

 portions as freely as do the Eucalypts which grow on less siliceous or 

 on basic soils, this available mineral material would soon be exhausted 

 and the growth of the tree would cease ; but some of the largest trees of 

 these species must be many hundreds of years old. 



The mineral matter stored in the timber of the four above-named 

 species, calculated on the anhydrous timber, is as follows (3): — • 



E. regnans 0'054 per cent. 



E. Delegatensis 0038 



E. obliqua 0025 



E. pilulaiis 0-052 



These values are obtained from tunbers collected from five widely 

 distributed localities. 



Although the amount of ash constituents in the woody portions of 

 the species referred to is so small, a much larger quantity is found in 

 their leaves, those of E. regnans giving 2.85 per cent, of ash, those of 

 E. pilularis 2.91 percent. 



The buds, petioles, seed-cases and seeds also contain a considerable 

 amount of mineral matter; thus in the case of E. pilularis: — 



Buds with petioles .... 3'79 per cent. 



vSeed-cases (fruits) 2*89 „ 



Seeds 104 



The mineral matter in these portions of the tree, like that of tlie 

 leaves, would obviously be available for repeated use. 



A striking peculiarity of several groups of Eucalypts is the compara- 

 tive constancy of the amount of manganese in the ash of the timber 

 of a given species from trees grown over the whole range covered by 



