24 
DARWINISM 
CHAP. 
river sometimes rose 30 feet in eight hours, doing immense 
destruction, and the abundance of the larger carnivora and 
large reptiles on its banks, he goes on : “ But it was among 
the flora that the principle of natural selection was most 
prominently displayed. In such a district — overrun with 
rodents and escaped cattle, subject to floods that carried away 
whole islands of botany, and especially to droughts that dried 
up the lakes and almost the river itself — no ordinary plant 
could live, even on this rich and watered alluvial debris. The 
only plants that escaped the cattle were such as were either 
poisonous, or thorny, or resinous, or indestructibly tough. 
Hence we had only a great development of solanums, talas, 
acacias, euphorbias, and laurels. The buttercup is replaced by 
the little poisonous yellow oxalis with its viviparous buds ; the 
passion-flowers, asclepiads, bignonias, convolvuluses, and climb¬ 
ing leguminous plants escape both floods and cattle by climb¬ 
ing the highest trees and towering overhead in a flood of 
bloom. The ground plants are the portulacas, turneras, and 
cenotheras, bitter and ephemeral, on the bare rock, and almost 
independent of any other moisture than the heavy dews. 
The pontederias, alismas, and plantago, with grasses and 
sedges, derive protection from the deep and brilliant pools ; 
and though at first sight the ‘monte’ doubtless impresses the 
traveller as a scene of the wildest confusion and ruin, yet, on 
closer examination, we found it far more remarkable as a 
manifestation of harmony and law, and a striking example of 
the marvellous power which plants, like animals, possess, of 
adapting themselves to the local peculiarities of their habitat, 
Avhether in the fertile shades of the luxuriant ‘monte’ or on 
the arid, parched-up plains of the treeless pampas.” 
A curious example of the struggle between plants has 
been communicated to me by Mr. John Ennis, a resident in 
New Zealand. The English water-cress grows so luxuriantly 
in that country as to completely choke up the rivers, 
sometimes leading to disastrous floods, and necessitating great 
outlay to keep the stream open. But a natural remedy has 
now been found in planting willows on the banks. The 
roots of these trees penetrate the bed of the stream in every 
direction, and the water-cress, unable to obtain the requisite 
amount of nourishment, gradually disappears. 
