PRESIDENTIAL ADDRESS. 37 



ation, and consequently it is compatible with such an 

 endeavour, that those species having the thickest epidermis 

 and of which such as E. dumosa may be taken as a type, 

 are commonest in the Interior. But this particular char- 

 acter is to be met with intermittently in all the four 

 climatic divisions of New South Wales, so that it wouid 

 appear that various species have adopted this precaution 

 for preservative objects but from different causes. A 

 dwarfed Port Jackson form of E. capitellata has remark- 

 ably thick almost orbicular leaves, while large normal type 

 specimens within a few miles have lanceolate foliage of 

 ordinary thickness. The thick-leaved form however grows 

 in the more exposed positions, and in the more rocky situ- 

 ations with probably less plant food available. It seems 

 therefore not improbable that in order to counteract the 

 effect of strong winds, to which its exposure renders it 

 liable, and also to compensate in some way for the limited 

 nourishment it obtains, that the thick-leaved adaptation 

 has been evolved in this case, to preserve the starch which 

 forms in the leaf and which is regarded as an auxiliary 

 food supply. It is of interest to note that the thickest 

 leaved types usually correspond with the more dwarfed 

 forms, and when the same species at maturity occurs both 

 as large and as stunted trees, it is on the latter that the 

 thickest leaves are found. 



Turning next to the Eucalypts in the cold climate we 

 find a similar variation in leaf characters. The foliage of 

 E. Gunnii as dwarfed trees on Mount Roland in Tasmania 

 at nearly 4,000 feet above sea level, is distinctly thicker 

 in texture than that of the same species around Guildford 

 Junction at an altitude of 2,000 feet, and where the trees 

 are upwards of 80 feet high. 



The leaves of E. coriacea are always somewhat leathery 

 as the specific name would imply, but in observing trees 



