similar moist regions of the Himalaya and Japan. Whether their absence over the 

 Chinese plains may not be due in part to the thorough cultivation of these plains 

 through thousands of years, and to the removal of the trees and shrubs for fuel, we do 

 not yet know. In all probability however they had disappeared over the dry plains 

 long before cultivation could affect them. 



We find however, that certain Reuverian species are either still living in Europe, 

 or are more nearly allied to living European forms than to those of China, and it is 

 noticeable that many of these are large*seeded. Among these we may instance Picea 

 excelsa, Quevcus Robur, Cavpinus Betulus, Corylus Avellana, Prunus spinosa, Ilex Aqui= 

 folium, Vitis vinifera, and a Fagus allied to F. silvatica. With the exception of the vine, 

 the northernmost range of all these plants now lies very considerably to the north of 

 Limburg. That is to say, they are all plants which by moving somewhat further south, 

 perhaps to the south of France or the Caucasus, could survive the cold of the Glacial 

 Period without being obliged to cross the mountains. We speak more particularly of 

 these large*seeded trees, for little difficulty would occur with smallsseeded plants; these 

 latter can easily be carried across mountains, and as we shall see, it is among the trees 

 and shrubs (mostly largesseeded) that the greatest extermination has taken place. The 

 ease with which smallsseeded species can be transported great distances across barriers 

 is well seen by the figures given in Hooker's "Outlines of the Distribution of Arctic 

 Plants". Here he shows that 75 per cent, of the species of Arctic Europe cross the Alps, 

 and 20 per cent, cross the Mediterranean. But, with the exeption of about 10 species 

 out of the 450 so transported, all are smalkseeded forms. 



It is necessary to make clear these facts of the present-day relationships of the 

 Reuverian flora, also of the character of the seeds of plants which have been preserved, 

 and which have been exterminated; they have an important bearing on the causes of 

 geographical distribution in the present and past, and on the preservation or extinction 

 of genera and species in different parts of the world. 



Other facts emerge, which throw light on the same questions. It has already 

 been mentioned in passing that the nearest congeners of the Reuverian plants now 

 inhabiting southern China, are nearly all mountain plants. The same is true of nearly 

 all congeners which inhabit southern latitudes, in whatever part of the Northern Hemi* 

 sphere they occur. Thus Pterocavya hupehensis, Meliosma Veitchiorum and M. Beaniana, 

 Stewartia Pseudo=camellia, Diospyros Lotus, Camptotheca acuminata, and the nearest living 

 species of Actinidia, all inhabit the temperate belt of the Chinese mountains. Zelcowa 

 Keaki, Orixajaponica, Phellodendronjaponicum inhabit the mountains of Japan. Hehvingia 

 himalayaca, Bucklandia populnea, and Pyrularia edulis inhabit the Himalaya, the last of 

 these three having been found also in Western China by Dr. Augustine Henry, though 

 till lately the specimen was overlooked. The different species of Covylopsis are natives 

 of the Himalaya and the mountains of China and Japan. Liquidambar orientate belongs 

 to the mountains of Asia Minor. Vitis vinifera is found in the Caucasus, the mountains 

 of Greece and the Orient. AEsculus Hippocastanum has a similar range, but extends also 



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