THE GENERAL HISTORY OF TIIK PLANTS. '. 



battalion of the great subantarctic or antarctic plant army, held 

 now in bondage by their northern conquerors. Farther south tin- 

 beeches are more powerful: but. driven from the fertile land, they 

 occupy the poorer soil of the lowlands or the inhospitable mountain- 

 slopes, where they oppose a solid front to the biting blasts. 



A remarkable example of the restricted distribution of a tree i.s 

 shown by the kowhai of Chatham Island. This plant is common on 

 certain volcanic ground near Auckland City. It was formerly ex- 

 tremely abundant in the Catlin's River forest, and in fact is found all 

 over New Zealand, growing in various distinct kinds of soil. But in 

 Chatham Island you may search the forest everywhere and find no 

 trace of this graceful tree except on the limestone country near the 

 edge of that extensive lagoon, the Whanga. There it is abundant, in 

 company with the ordinary trees of a Chatham Island lowland forest, 

 which latter elsewhere occupies volcanic ground. Here, then, is 

 some slight advantage, not yet estimated by science, afforded to the 

 ordinary trees by the volcanic soil which enables them to exclude 

 the kowhai ; whereas the limestone soil does not afford this 

 benefit, and there all the trees meet on equal terms, flourish! i in 

 side by side. 



How many plants of which no trace has been found, may have 

 existed in New Zealand, and mav have been destroved through, changes 



. . ' c? 



of conditions leading to some slight advantage for their competitors, 

 none can tell ; but that many ancient types of surpassing interest 

 must have so perished is quite well known from such fossil plants as 

 have been found, and amongst which, side by side with existing gener; 1 .. 

 are others not now to be found in any part of Australasia. 



How PLANTS CHANGE THEIR FORMS. 



It has been shown above how a constant warfare goes on between 

 the plant inhabitants of the most quiescent forest or meadow. ;-.nd 

 how some survive and others perish. This truth forms the corner- 

 stone of the doctrine of evolution. Just as there is no actual stability 

 in the vegetation of a region, so is there none in the individual species. 

 Constant change is the undeviating plan of nature. 



The original plant-immigrants settling down in their r.e\v home 

 would be exposed to novel conditions of soil and climate, and to con- 

 tact with other plants and animals. This new environment would 

 possibly bring about slight changes in the organisms, and in time 



