106 REPORTS ON THE STATE OF SCIENCE. — 1915. 



- A few constituents of the oils have apparently no distinctive 

 botanical support; such is the (solid) paraffin (19) which has already 

 been isolated from such diverse species as E. acervula and E. Smithii. 

 This paraffin appears to be a constant constituent in the oil of the latter 

 species; when purified it melts at 64° C. but that isolated from 

 E. acervula melts at 55° C Further research, however, may show 

 distinctive characters here also. 



Eudesmol, the chief stearoptene of Eucalyptus oils, occurs in those 

 derived from different groups but is found in greatest abundance in 

 species yielding phellandrene in quantity, although it also occurs in 

 the oil of E. Macarthuri from which phellandrene is absent. 



It is necessary that these rarer chemical constituents should be 

 more fully investigated and isolated from the species containing them ; 

 it might then be possible to establish definite rules, both botanical and 

 chemical, to account for their occuiTeiice and so bring them into 

 conformity with those other botanical and chemical chai'acteristics the 

 co-ordination of which has now been fairly well established. 



The Development of the Genus Eucalyptus. By E. H. Cambage. 



The earliest evidence we have of the existence of the genus Eucalyp- 

 tus in Australia is that furnished by the fossil leaves and what are 

 regarded as authentic specimens have been found as far back as in the 

 Miocene period. The Mornington Beds of Victoria, from which 

 Eucalyptus fossils have been obtained, are doubtfully referred to the 

 Eocene period (20). In early Miocene times our present mountain 

 system had: not been developed and the climate was mild to warm (21). 

 Eastern Australia^ was then fairly level and was largely composed of 

 siliceous soils, much of the silica being in a free state and the soils 

 sandy. Subsequent lava-flows and deposits of volcanic tuffs gave rise 

 to a more basic soil ; the final uplift, parallel to the east coast, towards 

 the close of the Tertiary, produced elevations which have a cold climate. 



The effect of geological formation upon the distribution of the 

 Eucalypts, though distinctly evident in many localities, is to some 

 extent of a local nature, being dominated by the influence of climate. 

 Broadly speaking, Eucalynts are distributed between two extreme types 

 of geological formations, the siliceous and the basic ; there are numerous 

 examples of different species approaching each other up to a common 

 boundary without intenningling — some growing on a siliceous granite or 

 sandstone formation, in which there is an abundance of free silica, 

 others on a basalt or other basic rock, giving rise to a clay soil (1). 

 Many of the Eucalypts, including those which are now regarded as the 

 oldest living types, require a soil derived from rocks containing upwards 

 of 70 per cent, silica. 



The final uplift throughout Eastern Australia had considerable effect 

 upon the Eucalypts of that area. The resultant Main Divide separated 

 the original uniform climate into tliree ; with its fairly steep eastern face 

 presented to the ocean, it created tnoister conditions over the coastal 

 area, cooler conditions on the mountains, whilst upon the lower portions 

 of the western side the effect was to produce a drier as well as a hotter 

 summer and colder winter climate. The Eucalypts, towards the 



