FOREST GEOGRAPHY AND ARCHOLOGY. 221 
continent specifically unchanged, though hardly developed as 
forest trees on the Pacific side. There are probably, but not 
certainly, one or two instances on the northern verge of these 
two forests. There are as many in which eastern and west- 
ern species are suggestively similar. The Hemlock Spruce of 
the northern Atlantic States and the Yew of Florida are ex- 
tremely like corresponding trees of the Pacific forest; indeed 
the Yew-trees of all four regions may come to be regarded as 
forms of one polymorphous species. The White Birch of 
Europe and that of Canada and New England are in similar 
case ; and so is the common Chestnut (in America confined 
to the Atlantic States), which on the other side of the world 
is also represented in Japan. A link in the other direction is 
seen in one Spruce-tree (called in Oregon Menzies Spruce) 
which inhabits northeast Asia, while a peculiar form of it 
represents the species in the Rocky Mountains. 
But now other and more theoretical questions come to be 
asked, such as these : — 
Why should our Pacific forest-region, which is rich and in 
some respects unique in coniferous, be so poor in deciduous 
trees ? 
Then the two Big Trees, Sequoias, as isolated in character 
as in location, — being found only in California, and having 
no near relatives anywhere, — how came California to have 
them? 
Such relatives as the Sequoias have are also local, peculiar, 
and chiefly of one species to each genus. Only one of them 
is American, and that solely eastern, the Taxodium of our 
Atlantic States and the plateau of Mexico. The others are 
Japanese and Chinese. 
Why should trees of six related genera, which will all thrive 
in Europe, be restricted naturally, one to the eastern side of 
the American continent, one genus to the western side and 
very locally, the rest to a small portion of the eastern border 
of Asia? 
Why should coniferous trees most affect and preserve the 
greatest number of types in these parts of the world? 
And why should the northeast Asian region have, in a 
