Kirk. — On the Naturalized Plants of Port Nicholson. 363 



speedily destroy the undergrowth, admitting the Hght and air. These in their 

 turn act unfavourably on the larger vegetation which has attained its 

 growth in a dark damp atmosphere, and the injurious agency gradually 

 extends over a constantly widening area. But in this colony it rarely 

 happens that the process of displacement passes into complete replacement ; 

 it rarely or never results in the extirpation of indigenous species, although 

 it greatly reduces the number of individuals. The admission of air and 

 light, while unfavourable to certain plants, tends to increase the vigour of 

 others, which exhibit a luxuriant growth they had never before displayed, 

 and 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 struggle for existence with the introduced 

 forms, and the restriction of those less favourably adapted to habitats which 

 afford them special advantages. This, in brief, is a statement of the 

 phenomena now in progress throughout the colony ; but at present we are 

 not in a position fully to appreciate several of its bearings. 



It can scarcely be expected that those who were familiar with the general 

 features of the vegetation of New Zealand before they were modified or 

 changed by the progress of settlement will at once accept the statement I 

 have given as correct. They have witnessed the steady onset of axe and 

 fire, the unceasing advance of cattle and sheep, and they have been so 

 impressed with the almost total extinction of many striking plants over 

 areas where they were formerly abundant, as to have lost sight of the 

 tenacity with which plants in general maintain their existence even under 

 unfavourable conditions, of the surprising power of adaptation which 

 they often exhibit under changed circumstances, and are led to the 

 conclusion that sooner or later the majority of our native plants 

 must inevitably become extinct. I can only share in this fear to a 

 limited extent, and could almost count upon my fingers the particular 

 plants for which such a danger is most to be feared. In no part 

 of the world has agriculture been carried to a higher pitch of perfec- 

 tion than in the British Islands ; in no part have the open lands been 

 more completely brought under cultivation ; yet we know that under 

 these adverse circumstances not more than two or three species, at most, 

 have become extinct, although many have become extremely rare, and only 

 maintain themselves in situations offering peculiar advantages. The 

 Killarney fern, Trichomanes radicans, Sw., has often been reported as 

 extinct, yet scarcely a year passes without some new station being disco- 

 vered, or some of the old stations proving reproductive. Asplenium 



