ACCLIMATISATION CENTRES AND MIGRATION ROUTES 325 



Furthermore, it must be taken into account that there existed along 

 the route insects, grubs, and blights also of European origin. 



It is possible there may have been another inducement to follow the 

 coastal route ; there may have been an instinctive attraction to the sea, 

 that great plain over which the old-world ancestors of imported species 

 for generations have ventured. 



The second of these animal highways was the hill-top route. Wide 

 belts of impenetrable forest covered the slopes forests still standing as 

 late as the 'eighties. They extended from ocean almost to mountain- 

 top, heaviest timber growing along the coast zone, trees lower in height 

 roped in tangles of "lawyer," vine, and supple-jack on the foothills and 

 lower slopes. There was another reason why migrants were forced on to 

 the tops. It was the only route by which the river gorges that furrow 

 the flanks of the main ranges could be avoided, gorges always difficult 



Line of light mountain-top route through forest. 



of access and often impassable. The line of summit was the line of 

 comparative light and comparatively open ground. Although there 

 existed nothing approaching a continuity of bare ground, although the 

 line of light was broken and checkered, there were here and there at 

 least reaches of uncovered summit, rockfalls of jumbled stone, windblows 

 where gales had swept off the top soil, lucid intervals of turf. These 

 spots and stretches upon which, at any rate, the sun could shine and 

 where migrants could touch ground unshaded by foliage, were as stepping- 

 stones encouraging advance across a river ford. Compared with the 

 gloom and tanglement of the damp forests they must have been oases 

 pleasant to reach. They offered freedom and light as against unknown 

 possibilities of danger and darkness. 



The third line of migratory movement was the river-bed route. 

 Particularly alluring has this route proved to migrants where a confused 



