THE ORGANIC ENVIRONMENT 25 



change is noted. In Western Australia, in particular, 

 the tall grass has first to be eaten down by cattle. 

 Darwin was puzzled to know whether the change was 

 due to the introduction of new species of grass, to the 

 altered growth of the existing species, or to a change 

 in their proportional numbers.* Perhaps the reader 

 who knows still less about Botany than the eminent 

 naturalist professed to do might plausibly conjecture 

 that the change is to be ascribed to the joint operation 

 of all three causes. He would be wrong, however. 

 It is the new grasses that change the complexion of 

 a country. These are the companions and allies of the 

 invading colonist, as the old grasses were of the indi- 

 genous inhabitants. That new species are introduced 

 has been proved by the naturahst, Azara, who found 

 a number of new plants in the track of horses. What 

 he says of wild horses is true of other species, especially 

 of dogs and of cattle. It is in the track of cattle that 

 the grasses have sprung up on the pampas. 



A like change, though not quite of the same nature, 

 took place in Australia. There was grass everywhere, 

 said an early colonist ; yet it was thin. Then the soil 

 was, as it were, electrified by the touch of colonisation. 

 Trees and plants flourished where there had been 

 nothing larger than scrub or shrub. A change of 

 vegetation took place, and the very climate was modified. 

 A district that had been parched and waterless showed, 

 after a few years feeding, water permanently standing. 

 Sometimes a tufty herbage was changed into a sward. 

 It became a good level turf, intersected with runnels |. 



The same phenomenon was to be found in the neigh- 

 bourhood of the Lachlan river. The rich river-flata 

 there afford fine feed for stock. Above them are 

 plains that extend for hundreds of miles, covered 

 with a low scrub. In the hollows some fine silvery 

 grass grows, but the tops are devoid of vegetation. 

 That was in 1844. Ten years later the whole of the 



* Dakwin, Voyage of the Adventure, ch. vi. 

 t Ranken, Bush Essays, p. 5. 



