MACLOSKIE: CHARACTER AND ORIGIN OF PATAGONIAN FLORA. 955 



many other plants would thrive there, if only they could find an entrance. 

 This consideration also helps to account for the absence of trees, inasmuch 

 as after the extinction of large Patagonian glaciers, from none of the 

 adjoining lands have trees been able to invade the vacant territory. The 

 chain of the Andes from which alone they could come has few large trees 

 southwards, and none suitable for the soil and climate of the plains or the 

 intersecting valleys. That trees have no objection to Western Patagonia, 

 or to the Magellan and West Fuegian districts is evident from Professor 

 Dusen's summary. It is within the possibilities that the Patagonian region 

 may yet be improved by the judicious introduction of trees and shrubs. 

 In extending our view further northwards we are struck by the fact that 

 the famous papers by Asa Gray and Joseph D. Hooker on the Origin of 

 the North American Flora, admit of extension in two directions, both 

 as to the terminus a quo and to the terminus ad quern. Instead of 

 starting from the Arctic regions or from Scandinavia our present knowl- 

 edge of plant-distribution points very strongly and directly to Central 

 Asia as the home or distributing center of the plants of all the temper- 

 ate and colder parts of the world. The Arctic regions are rather remark- 

 able for the absence of endemic species, but have formed a convenient 

 bridge for the passage to and fro of forms belonging to the less rigorous 

 parts of both hemispheres. Their Old World connection is shown by the 

 examination of the Index Kewensis to be chiefly with the northern and 

 central parts of Asia. The Himalaya region is unique for the diversity of 

 its climate at its different elevations ; and sends colonies of its plants 

 westward, by Asia Minor to the Mediterranean region, and as far as the 

 Canary Ids. ; southwestward to Arabia and Africa ; across the Orient 

 to Australia ; eastward to China and Japan ; and northwestward to 

 Europe. 1 The course of distribution of animals has been similar ; 

 the Elephants migrated from the foot of the Himalayas to ^western 

 Europe as far as Great Britain, and even to the cold parts of northern 

 Asia, and over into Alaska, whence they spread over parts of America, 

 reaching as far as Patagonia. The distribution of the Mosquitoes ex- 

 hibits the same tendency. 2 And in a recent paper in Nature upon 



1 See A. F. W. Schimper {Pflanzengeographie, 786 sqq.) on the diversity of climate and richness 

 of vegetation of the Himalayan Region. ^ 



2 Monograph of Culicidae, F. V. Theobald, British Museum, 1901. Observe especially the 

 distribution of Culex nigripes, the Scourge of Alaska, from Kashmir. 



