YORKSHIRE NATURALISTS UNION. 
The tropical rain-forest is es})ecially remarkable for the rich 
variety of its generic and specific life, bnt this miscellaneous aggre- 
gation of tropical vegetation is essentially regressive and weak, its 
component s])ecies being believed to have formerly enjoyed a more 
extended distribution than that to which they are now restricted : 
the rain-forest really constituting a sanctuary or refuge for weakei 
organisms of varied origin and shar])ly contrasting with the social 
methods of growth which gives such noticeable uniformity to the 
I^uropean forests. 
Fig. 11. — ( ieourapliical distritiution of Forest Trees in Europe showing the occupation of the 
probable evolutionary region by the Heech, the most dominant and recently evolved tree and 
the expulsion therefrom of the Oak whose range has been made somewhat discontinuous by the 
uprising of the Beech and also showing the same chief path of migration from Europe as 
followed by other organisms (after Herghaus >. 
The Red shows the region wherein the Beech has arisen and is now dominant ; the Pukpi.e 
represents the regions in which the Oak is still supreme, and wherein the Beech has not yet 
spread or where it does not yet thrive so well; the (iKhen colour indicates the countries or 
districts characterized by the Evergreen Oak; the \'m.i,o\v denotes the mount.iin regions of 
Central Europe which are dominated by the SiKer Fir; the Blue shows the districts or countries 
where the Birch and Scots Pine are still the characteristic trees, though l)eing slowly driven 
further and further from the evolutionary area. 
Amongst tre^s the Beech ( Fugas sylvatiat) is the most recently 
developed and dominant species in the world, and although there 
are numerous other species of F(u/i(s dispersed over the earth, yet 
these are of earlier origin, and confessedly inferior in dominating 
power to the latest evolved Euro])ean species. In the British Isles 
it is, geologically speaking, a recent immigrant from the continent, 
and is driving ott the oak, the ash, and other trees, and monopolizing 
the more favorable positions and soils previously occupied by these 
species, as the beech can thrive beneath the shadow of any other 
tree, while none can prosper beneath the denser shade of the beech. 
That it is recently evolved and extending its range is confirmed by 
the ffict that although Denmark was overspread by beech forests 
