Chap, xi.] VERTICALLY DLSPOSED LEAVES. 22g 



Whilst we were hunting along the river bank, numerous 

 bright paroquets were flying about amongst the trees, and a 

 great flock of white cockatoos flew overhead, harshly screaming 

 at the danger. They settled in some trees near, but were far 

 too wary to let me get a shot, though I did my best to creep 

 on them. The smaller bright paroquets are not at all wary as 

 a rule, but are most easily shot. 



Grisebach, in his account of the Vegetation of Australia,* 

 dwells on the close relation of interdependence which exists 

 between the tree vegetation and the coating of grass which „ j_, 

 covers the ground beneath it ; and remarks, that the amount of '] 

 light allowed by the trees to reach the ground beneath them is 

 rendered more than usually great by the vertical position in 

 which their leaves grow. Hence the growth of the grass 

 beneath is aided. 



It may be that this permitting of the growth of other plants 

 beneath them, and consequent protection of the soil from losing 

 its moisture, besides other advantages to be derived, is the 

 principal reason why, as is familiarly known, two widely different 

 groups of Australian trees, the Eucalypti and Acacias, have 

 arrived at a vertical instead of a horizontal disposition of their 

 leaves by two different methods. 



The Acacias have accomplished this by suppressing the true 

 horizontal leaves, and flattening the leaf-stalks into vertical 

 pseudo-leaves or " phyllodes." The gum-trees, on the 

 other hand, have simply twisted their leaf-stalks, and have thus 

 rendered their true leaves vertical in position. There must 

 exist some material advantage, which these difl'erent trees 

 derive in common, from this peculiar arrangement, and the 

 benefit derived from relation to other plants by this means may 

 be greater and more important than that arising from the fact 

 that the vertical leaves have a like relation to the light on both 

 sides, and are provided with stomata on both faces. 



In support of this conclusion I was told, when at Melbourne, 

 that when the native vegetation was cleared away from under 

 gum-trees they ceased to thrive, and in time perished. I was 

 shown a number of gum-trees, not far from the city, scattered 

 over some public land, covered with only short turf, which 

 seemed to be mostly in a dying condition. 



April 2nd, 1874. — On the voyage to Sydney, two Fur Seals 

 were seen about the ship. They were of a smaller species 

 than that occurring at Kerguelen's Land. They swam along- 

 side with remarkable ease and rapidity, having in the water 

 just the appearance of porpoises. The hind limbs were 



* A. Grisebach, " Vegetation der Erde,"' p. 216. Leipzig, W. Engelman, 



1S72. 



