188 A. G. HAMILTON. 
when the low river hills covered with eucalypts interspersed with 
a few pines (Callitris verrucosa) are cleared, a thick scrub of pines 
springs up immediately, among which no other trees are able to 
survive, as they are smothered in youth by the dense growth of 
the young pines. And in the Western parts of the Colony the 
extension of the pine scrub is a matter for serious consideration 
to the pastoralists. 
Dr. R. v. Lendenfeldt says, ‘‘In 1863 there was little or no pine 
scrub (Callitris) in the Lachlan district. In 1883 the pine had 
taken possession of the district, and was rapidly superseding the 
angiosperm trees, which previously formed the forest in that 
district. It appeared to be only a question of time when the 
forest would be converted into a pine forest. In 1885, when 
engaged in collecting timber specimens, Mr. Ridstone could not 
obtain a single sound tree of any size with the exception of the 
pine. I myself visited the Mooramba district at the beginning 
of 1885 and found there a prevalence of pine, which was, accord- 
ing to the statements of old residents, a new acquisition in that 
district.”* Dr. von Lendenfeldt ascribes this to change of climate, 
a statement which I shall discuss later on under that head. 
We are all familiar with the fact that in the coast district and 
table-lands, when the land is cleared and seedling trees spring up, 
the wattles of one or more species usually outnumber all others in 
the proportion of two to one. In a piece of ground which I dug 
up during the past year, and which had lain fallow for years, 
seedlings of Acacia binervata came up in hundreds, and I did not 
observe any other species of tree, except one solitary seedling of 
Commersonia Frasert. That seeds may lie for a long time dormant 
in the ground is well known. Darwin says, ‘Out of one small por- 
tion of earth thus completely enclosed in the roots of an oak about 
fifty years old, three dicotyledonous plants germinated: I am 
certain of the accuracy of this observation.” + And there have been 
many well authenticated instances of a crop of plants new toa 
* Proc. Linn. Soc. of N. S. Wales, Vol. x., p. 721. 
+ Origin of Species, 6th Edit., p. 326. 
