ON THE STKUGrGrLE FOK EXISTENCE AMONGST PLANTS. 137 
the waste, cultivated, and virgin soil, in annually increasing 
numbers of genera, species and individuals. , Apropos of this 
subject, a correspondent (W. T. Locke Travers, Esq., F.L.S.) — - 
a most active New Zealand botanist — writing from Canterbury, 
says: “ You would be surprised at the rapid spread of European 
and other foreign plants in this country. All along the sides of 
the main lines of road through the plains, a Polygonum ( avicu - 
lare\ called c cow-grass,’ grows most luxuriantly, the roots 
sometimes two feet in depth, and the plants spreading over an 
area from four to five feet in diameter. The dock ( Rumex 
obtusifolius or R. crispus) is to be found in every river-bed, 
extending into the valleys of the mountain-rivers, until these 
become mere torrents. The sowthistle is spread all over the 
country, growing luxuriantly nearly up to 6,000 feet. The 
watercress increases in our still rivers to such an extent as to 
threaten to choke them altogether ; in fact, in the Avon, a still 
deep stream running through Christ Church, the annual cost of 
keeping the river free for boat navigation and for purposes of 
drainage, exceeds 3001. I have measured stems twelve feet 
long and three quarters of an inch in diameter. In some of the 
mountain districts, where the soil is loose, the white clover is 
completely displacing the native grasses, forming a close sward. 
Foreign trees are also very luxuriant in growth. The gum-trees 
of Australia, the poplars and willows, particularly, grow most 
rapidly. In fact, the young native vegetation appears to shrink 
from competition with these more vigorous intruders.” 
Dr. Haast, F.L.S., the eminent explorer and geologist, also 
writes to me as follows : — 
“ The native (Maori) saying is, c as the white man’s rat has 
driven away the native rat, as the European fly drives away our 
own, and the clover kills our fern, so will the Maoris disappear 
before the white man himself.’ It is wonderful to behold the 
botanical and zoological changes which have taken place since 
first Captain Cook set foot in New Zealand. Some pigs, which 
he and other navigators left with the natives, have increased and 
run wild in such a way that it is impossible to destroy them. 
There are large tracts of country where they reign supreme. 
The soil looks as if ploughed by their burrowing. Some station 
holders of 100,000 acres have had to make contracts for killing 
them at 6d. per tail, and as many as 22,000 on a single run 
have been killed by adventurous parties without any diminution 
being discernible. Not only are they obnoxious by occupying 
the ground which the sheep farmer needs for his flocks, but 
they assiduously follow the ewes w T hen lambing, and devour the 
poor lambs as soon as they make their appearance. They do 
not exist on the western side of the Alps, and only on the lower 
grounds on the eastern side where snow seldom falls, so that 
