PRESIDENTIAL ADDRESS. — 21 
of Callitris cannot yet be made. The knowledge of the 
identity of the predominant terpene in these African oils, 
together with that of the composition of their esters, 
whether bornyl- or geranyl-acetates, would probably assist 
towards suggesting a theory to account for the territorial 
distribution of the three genera. That they are very old 
seems conclusive, and that they were originally distributed 
over land connections now no longer in evidence seems 
also a reasonable conclusion. 
Professor Saxton, from his studies with Tetraclinis, 
recently published in the Annals of Botany, thinks that 
the southern sub-family Callitroidece were derived from 
the essentially northern sub-family Cupressoidecw, and from 
the available evidence suggests the former existence of a 
great Antarctic continent with a land connection between 
Southern Africa and southern Australia. 
It will probably be found that pinene was the earliest 
terpene in the leaf oils of these sections of the Coniferex, 
and that the other terpenes and oxygen bearing compounds 
developed later. Such aresult would bein agreement with 
those already obtained with some other large and ancient 
genera. 
The most important result so far derived from the phyto- 
chemical studies with the genus Eucalyptus, and the closely — 
related genus Angophora, is, perhaps, the intimate connec- 
tion shown to exist between the leaf venations of the 
mature lanceolate leaves of the several species and their | 
essential oil constituents. This striking correlation enabled 
suggestions to be formulated, particularly in respect to. 
Eucalyptus species with closely agreeing characters, which | 
when followed up led to a more intimate acquaintance with 
the genus, and, perhaps, has also been the means of stimu- 
lating research by workers in other directions, with very 
gratifying results. This frequently recurring agreement 
