122 NORTH AND SOUTH 



XXX 



The dominance of animals and plants indigenous to 

 North and- the northern temperate zone over those 

 South native to the corresponding region in the 

 southern hemisphere, is a commonplace of zoology and 

 botany. Safe and speedy transit through the tropics 

 is all that is required to enable many forms of northern 

 life, both animal and vegetable, to establish themselves 

 permanently in southern lands; but no instance has 

 been recorded of any animal, vertebrate or invertebrate, 

 or of any plant migrating from the southern hemi- 

 sphere and forming a successful colony in the northern 

 temperate zone. 



'The weeds of Europe,' says Professor Miall, 'do not 

 suffer when transported to the southern hemisphere, but 

 flourish and often drive out the native plants. The weeds of 

 the southern hemisphere are unable, however, to make things 

 even by invading any patch of ground in Europe. . . . 

 There is no reciprocity in the matter. Southern plants, and 

 more rarely southern animals, do now and then get access to 

 Europe, but they cannot maintain themselves there. All 

 kinds of foreign plants are brought over in ballast or wool, 

 and for a season or two they come up where they may chance 

 to be thrown out ; but when the supply ceases, native plants 

 quickly take their place. ... I know of not a single animal 

 native to a distant southern country which can maintain 

 itself in Europe.' 1 



Reference has been made earlier in these notes to 

 the calamity brought upon Australasian farmers by the 

 introduction of the rabbit. 2 Stoats and weasels brought 



1 Miall's Bound the Year, pp. 202, 203. 



2 See page 39 supra. 



