OnzzgsEMAN.— On. Naturalized Plants of Auckland District. 278 
competition with other species, in different localities and in different climates, 
they have gained a vigour of constitution and a faculty of adapting them- 
selves to a great variety of conditions which enable them to readily over- 
come plants that have not been so advantageously modified. 
This supposition will also throw some light on the curious fact that the 
vast majority of our plants are of northern origin. It is now generally 
admitted by geologists that the present continents are of immense antiquity, 
and that there has been no great alteration in the relative proportions of 
land and water during vast geological epochs. Mr. Darwin therefore argues 
that as the northern hemisphere has probably always possessed the most 
extensive continuous land area, so the wonderfully aggressive and colonizing 
power of its plants at the present time is due to development where the 
competition of species has been the most severe and long continued, owing 
to the presence of facilities for natural migration. The plants of the com- 
paratively isolated countries of the southern hemisphere have not been 
subjected to the same degree of competition, and consequently could not be 
so advantageously modified. 
It is difficult to predict the ultimate result of the struggle between the 
invaders and the natives. Many naturalists believe that the foreign species 
will succeed in displacing and exterminating a large section of the indigenous 
flora. Mr. Travers, for instance, goes so far as to say*—‘‘ Such, in effect, 
is the activity with which the introduced plants are doing their work, that 
I believe if every human being were at once removed from the islands for 
even a limited number of years, looking at the matter from a geological point 
of view, the introduced would succeed in displacing the indigenous fauna and 
fora." Also, in his presidential address to the Wellington Philosophical 
Society,t he states :—'' Indeed, I have no doubt, from the present compara- 
tive rarity of many plants which were formerly found in abundance in such 
districts ” (the sub-alpine portions of Nelson), ** that in a few years our only 
knowledge of them will be derived from the dried specimens in our her- 
baria.” On the other hand, Mr. Kirk, who has paid special attention to 
the naturalization of plants in New Zealand, and whose views are there- 
fore entitled to careful consideration, takes a much more hopeful view 
of the future of the native flora, In a paper on the naturalized plants 
of Port Nicholson,| he says :—‘ At length a turning-point is reached, the 
invaders lose a portion of their vigour and become less encroaching, 
while the indigenous plants find the struggle less severe and gradually 
recover a portion of their lost ground, the result being the gradual 
amalgamation of those kinds best adapted to hold their own in the 
* Trans. N.Z. Inst., vol. ii., p. 312. + Trans. N.Z. Inst., vol. iv., p. 359. 
ns. N.Z. Inst., vol. x., p. 363. 
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