16 Is the Eucalyptus a Fever-destroying Tree ? 



globulus, and others, July and August being the months 

 when this vegetation is in the same condition. (Specimens 

 shewn.) 



These facts to some extent account for the scarcity of oil 

 at the times mentioned, but it is worth recording that the 

 vigour of the eucalyptus is greater in some years than 

 others ; some years very little new growth takes place in 

 comparison with other years ; and that when the eucalyptus 

 is less vigorous in growth, the oil-cells are charged more 

 equally throughout the whole year. 



Bat to illustrate this further : In July, 1 873, the mallee 

 was in fine oil condition, each two tons of rough cu 

 branches, with their leaves, gave two gallons of oil. The 

 ground was well saturated with water, and the surrounding 

 country had a good overflow from the river Murray and its 

 tributaries. The dry season set in immediately after, and 

 the temperature of the air rose rapidly to summer heat, 

 ranging from 68° to 92°. 



In November, the country became greatly parched, and 

 the only fresh water obtainable was that from the Murray. 

 The oil product was reduced to fourteen pints, being a loss 

 of two pints per two tons weight of material. 



At the commencement of December, the yield had fallen to 

 twelve pints, and at the close of the year to nine pints, the 

 oil product gradually diminishing to the end of summer — the 

 end of March — when the supply fluctuated from eight to 

 four pints, the dry season still continuing. 



The amygdalina, in the Dandenong Kanges, 280 miles 

 S. E. of the mallee, and approaching the sea coast, produced 

 in the same winter, month of July, only one-fifth of its full 

 summer supply. 



The two preceding years were similar, but did not vary so 

 rapidly. On the other hand, in the year 1861, when my 

 experiments with this mallee vegetation were occasional, it 

 yielded as much volatile oil in December as when it was at 

 its height, in July of 1873 ; and the coast species kept up a 

 good supply with little change throughout the whole year. 



The mallee country, as we shall see presently, plays a very 

 important part in the climatic influences of Australia. But to 

 proceed with the evidence that the eucalypt volatile bodies are 

 set free in the air, we will examine the leaf and its surround- 

 ings more fully. The suspension of each leaf from the branches, 

 as before stated, is in a line with the axis of the tree ; in 

 such cases, " there is no difference in the anatomy of the two 



