XxXiv INTRODUCTION. 
Notwithstanding the different and often greater means of dispersal possessed by plants, 
it is surprising how very similar are the broad features of the distribution of plants and 
animals. Doubtless this is owing in part to interdependence; and extensions of area 
of members of the two kingdoms have probably often been contemporaneous. Still, 
there are important divergences, and the primary regions of plants and animals cannot 
always be held as conterminous; assuming, of course, that Wallace has adopted the 
most natural divisions that could be found. This is most strikingly exemplified in the 
northern floras. Wallace was able to keep separate the eastern and western hemispheres, 
even in the north; and his palearctic and nearctic regions he defends against the opinion 
of Huxley *, the endemic element being nearly equal in the two. On the merits of the 
question of one or two primary northern zoological regions it is not proposed to enter ; 
but such a division cannot well be sustained in the vegetable kingdom, the alternative 
being more than two. Dr. Asa Gray long ago f pointed out the intimate relationships 
existing between the floras of Japan and North America, especially eastern North 
America: and the rich collections from Central China received at Kew within the last 
two years have added considerably to the number of genera, and almost identical 
species, common to Eastern Asia and Eastern America. Many of these extend to the 
mountains of North India, and a very few farther westward; but the affinities of the 
Floras of Eastern Asia and Eastern America are vastly greater than either exhibits 
with that of Europe. It is only in the higher latitude of North Corea and Mandshuria 
and northward that the vegetation bears a strong likeness to the European; but even 
there the relative proportion of woody plants is much higher than in Europe ~. How- 
ever, it seems clear that the whole north temperate and arctic flora is better considered 
as forming one primary botanical region, with extensions, or remains of extensions, 
through the mountain-chains to the Australasian Alps, Tierra del Fuego, and the. 
mountains of Tropical Africa, with only very faint traces in South Africa §. 
The alternative of more than two primary northern botanical regions seems quite 
inadmissible ; and this is tbe opinion of Engler, who has also specially examined the 
paleontological evidence, which proves that many of the genera of E. Asia and Eastern 
N. America formerly existed in Europe. If more than one primary northern region 
be admitted, we must, like Drude, recognize five or six; and, after all, there are no 
* See ‘ Proceedings of the Zoological Soviety of London,’ 1868, pp. 313-319 : “ the Geographical Distribution 
of the Alectoromorphe,” where the author suggests the propriety of two primary zoological regions, namely, a 
northern and a southern. As an alternative he proposes four primary regions, namely: 1. Arctogea (practi- 
cally Europe, Asia, North America, and Africa); 2. Austro-Columbia (South and Central America); 3. 
Australasia (Australia and New Guinea to Celebes and the Philippines); and 4. New Zealand. 
+ ‘Memoirs of the American Academy of Arts and Sciences,’ n. s. vi. 1858-59; and more fully elaborated 
by Engler, ‘ Versuch,’ i. pp. 22-43 (1879). 
~ Maximowicz in Bull. Congr. Intern. Bot. et Hort. St. Petersb. 1884, p. 152. 
§ Sir Joseph Hooker enters fully into the distribution of “Scandinavian Forms,” Transactions of the 
Linnean Society, xxiii. p. 251. 
