ON THE STRUGGLE FOR EXISTENCE AMONGST PLANTS. 139 
Still the fact remains as yet unaccounted for, that annual 
weeds, which, except for the' interference of man, would with 
us have no chance in the struggle with perennials, in New Zea- 
land have spread in inconceivable quantities into the wildest 
glens, long before either white men or even their cattle and flocks 
penetrate to their recesses. Such is the testimony of Drs. 
Haast and Hector, and Mr. Travers, the original explorers of 
large areas of different parts of the almost uninhabited middle 
island, and who have sent to me, as native plants, from hitherto 
unvisited tracts, British weeds, that were not found in the island 
by the careful botanists (Banks, Solander, Forster, and Sparr- 
mann) who accompanied Captain Cook in his voyages; and 
which were not found by the earlier missionaries, but which of 
late years have abounded on the low lands near every settlement. 
This subject of the comparative great vis-vitae of European 
plants, as compared with those of other countries, involves 
problems of the highest interest in botanical science, and the 
subject is as novel as it is interesting ; it is quite a virgin one, 
and requires the calmest and most unprejudiced judgment to 
treat it well. It cannot be doubted that the progress of civili- 
sation in Europe and Asia has, whilst it has led to the incessant 
harassing of the soil, led also to the abundant development of 
a class of plants, annual, biennial, and perennial, which increase 
more rapidly and obtain a greater development when ' trans- 
planted to the Southern hemisphere, than they have hitherto 
done in the Northern, and that, in this respect, they contrast 
strikingly with the behaviour of plants of the Southern hemi- 
sphere when transplanted to the Northern ; and hitherto no con- 
siderations of climate, soil, or circumstance, have sufficed to 
explain this phenomenon. 
