SEQUOIA AND ITS HISTORY. 587 
by identical or by closely similar forms! The same rule holds on 
a more northward line, although not so strikingly. If we: com- 
pare the plants, say of New England and Pennsylvania (lat. 45°- 
47°), with those of Oregon, and then with those of northeastern 
Asia, we shall find many of our own curiously repeated in the 
latter, while only a small number of them can be traced along the 
route even so far as the western slope of the Rocky Mountains. 
And these repetitions of East American types in Japan and neigh- 
boring districts are in all degrees of likeness. Sometimes the one 
is undistinguishable from the other ; sometimes there is a difference 
of aspect, but hardly of tangible character; sometimes the two 
would be termed marked varieties if they grew naturally in the 
same forest or in the same region; sometimes they are what the 
botanist calls representative species, the one answering closely to 
the other, but with some differences regarded as specific ; sometimes 
the two are merely of the same genus, or not quite that, but of a 
single or very few species in each country ; when the point which 
interests us is, that this peculiar limited type should occur in two 
antipodal places, and nowhere else. 
It would be tedious, and except to botanists abstruse, to enum- 
erate instances ; yet the whole strength of the case depends upon 
the number of such instances. I propose, therefore, if the Asso- 
ciation does me the honor to print this discourse, to append in a 
note, a list of the more remarkable ones. But I would here men- 
tion two or three cases as specimens. 
Our Rhus Toxicodendron, or poison ivy, is very exactly repeated 
in Japan, but is found in no other part of the world, although 
a species much like it abounds in California. Our other poisonous 
Rhus (R. venenata), commonly called poison dogwood, is in no 
oy represented in Western America, but has so close an analogue 
a Japan that the two were taken for the same by Thunberg and 
Linnæus, who called them both R. Verniz. 
Our northern fox-grape, Vitis Labrusca, is wholly confined to 
ead Atlantic States, except that it reappears in Japan and that 
regi 
The original Wistaria is a woody leguminous climber with showy 
_ blossoms, native to the Middle Atlantic States; the other species, 
Wa we so much prize in cultivation, W. Sinensis is from China, 
48 its name denotes, or perhaps only from Japan, where it is cer- 
tainly indigenous. 
