80 College of Forestry 
lated peaks it appears to me scarcely necessary to assume that 
its establishment on these peaks dates back to any such re- 
mote period even as the close of the Glacial epoch, since fac- 
tors at present operative might account for the carrying of 
such species to any habitat suited to them, at least in the 
northern continents.’ 
Extra-Continental Relations of the New York Flora. 
The case just considered of arctic plants on the Adiron- 
dack summits brings to a point the question which has sug- 
gested itself all along through the review of pre-glacial and 
post-glacial development and movements of vegetation, 
namely; has all this history had any relation to the Eur- 
Asian continents whose land masses together with that of 
North America converge about the north polar regions? The 
matter has been discussed from the time of Gray and Hooker, 
notably by Engler, Drude and more recently by Fernald, by 
Chamberlain and Salisbury and by Harshberger.* 
It is not a question to be gone into minutely in this bulle- 
tin, but certainly such a biologic matter has more than a 
passing interest for the thoughtful man. I would put it on 
the basis of an analogy with racial movements in human 
history which are of course of fundamental consequence in 
the study of human progress. Indeed it is certain that the 
study of biologic phenomena of the kind embraced in the 
development and movements of plants and animals gen- 
erally would greatly enlarge the horizon as respects a larger 
view of the history of man. It is precisely because of this 
conviction that I have ventured to put into this bulletin so 
large an element of what may appear to be speculative 
biology. Biologists — scientists generally — have gradually 
1In this connection, see Engler, A. On the behavior of plants of 
the north-temperate zone in their transmission to the high mountains 
of tropical Africa. London. Rep. Brit. Assoc. Adv. Sci. 1904:799_-801. 
Also Engler, A. Polymorphe Pflanzentypen der nérdlich gemissigten 
Zone bis ihrem Uebergang in die Afrikanischen Hochgebirge. Ascher- 
son Festschrift, 1904:552. 
2See Harshberger, Phytogeographic Survey of North America, pp. 
45-92, for specifie citations of literature bearing on this. 
