PRESIDENTIAL ADDRESS. ao 
South Wales, and complete material could readily be 
obtained in the immediate neighbourhood of Sydney, 
although any other closely related species would, no doubt 
have served the purpose as well. The comparative con- 
stancy of the results with the mineral constituents in this 
species is remarkable, and it is evident that some directing 
influence must be responsible for this similarity in amount 
of mineral contents of trees of one species growing at 
localities so far apart. 
The highest ash content in the timbers of this species 
tested was 0°088 per cent. of the anhydrous wood. This — 
was obtained from a tree growing at Marrickville (tree 
No.1). The lowest amount was 0°029 per cent. from a 
commercial specimen from the North Coast, the next being 
0°037 per cent. from another Marrickville specimen (tree 
No. 2). The mean of the six samples from the above 
localities was 0°0518 per cent. of ash, or one ton of the 
timber of this species would only contain about 1 fb. 24 
ounces of mineral matter. From these agreeing results it 
may be expected that the big tree of EH. pilularis above 
mentioned will also be in agreement, and that the anhy- 
drous wood of its trunk probably only contains about one 
15,000th part by weight of lime (CaO) and one 30,000th part 
of magnesia (MgO), while the manganese will only represent 
one part in about 900,000 parts by weight of the timber. 
It seems difficult to understand in what manner such 
minute portions of mineral substances could assist con- 
struction, if not largely catalytic. The results with two 
distinct trees of H. pilularis growing on the sandstone 
formation at Marrickville show, however, that trees which 
contain only about 0°05 per cent. of total ash in the wood 
have almost 3 per cent. of mineral matter in their leaves, 
while the buds and petioles contain about 3°8 per cent. The 
constituents of the ash of the leaves are in much the same 
C—May 6. 1914. 
