EuTLAND. — The Fall of the Leaf. 117 



Plagianthus betuUnus and Sophora tetraptera, growing as they 

 do in small groves, the trees far apart and interspersed with 

 brambles — Rnbus austraUs and other tangled bushes — invari- 

 ably recall the woods of the mother- comi try when observed in 

 winter. 



That these deciduous trees would soon overspread much of 

 the low land in this valley were the mixed forest removed, 

 and thus give a more boreal appearance to the district, is 

 shown by the abandoned clearings made by the natives prior 

 to the introduction of cattle and foreign weeds. 



Whatever may have been the nature of the European flora 

 at the commencement of the glacial period, Avhen the cold 

 attained its maximum the aspect of the region would be coin- 

 pletely altered. What was previously, and is now, the north 

 temperate would be included in the frozen zone, and the 

 limit of arborescent vegetation removed far south. 



Having evidence that the reindeer then roamed throughout 

 central France, we cannot give to the shores of the Mediter- 

 ranean a climate milder than is at present enjoyed by the 

 British Islands. Thus shorn, as it were, of the most genial 

 portion of its climate, the vegetable production of Europe 

 w^ould be correspondingly reduced. Only those species 

 capable of withstanding severe cold and of adapting them- 

 selves to every variety of soil could survive the southw^ard 

 movement of the flora enforced by the climatic changes. 



As we have seen that the tendency of the loweiing tem- 

 perature would be to induce the deciduous habit, and that in 

 the struggle for existence during the increasing cold the 

 deciduous would have a certain advantage over the evergi-een 

 tree, I think w^e may reasonably conclude that, however 

 largely the latter preponderated in the upper tertiary flora, 

 in the remnant that survived the glacial period the propor- 

 tion would be greatly altered, perhaps reversed. 



A comparison of the British flora with that of New Zea- 

 land reveals, besides the deciduous habit of the arborescent 

 species, so frequently referred to, other general differences 

 that demand explanation. For instance, though the phanero- 

 gamic plants of the British Islands exceed those found within 

 the New^ Zealand group, the latter flora contains a much larger 

 number of arborescent forms, while, again, the British species 

 belong to fewer genera and fewer orders than are represented 

 in New Zealand. In the northern flora we seem to have the 

 more or less altered descendants of a few" original types, in the 

 southern flora the waifs and strays from some rich and varied 

 botanical region. 



As the glacial cold abated, as the snow disappeared from 

 the mountain-heights and the plains were freed from their 



