70 VEGETABLE POWER OF ACCOMMODATION. 
1870-1871 has introduced numerous plants from Northern 
Africa and other countries into France, and this vegetable 
emigration is so extensive and so varied in character, that it 
will probably have an important botanical, and even economi- 
cal, effect on the flora of that country.* 
The Canada thistle, Hrigeron Canadense, which is said to 
have accompanied the early French voyagers to Canada from 
Normandy, is reported to have been introduced into other parts 
of Europe two hundred years ago by a seed which dropped out 
of the stuffed skin of an American bird. 
Vegetable Power of Accommodation. 
The vegetables which, so far as we know their history, seem 
to have been longest objects of human care, can, by painstaking 
industry, be made to grow under a great variety of circum- 
stances, and some of them prosper nearly equally well when 
planted and tended on soils of almost any geological character ; 
but the seeds of most of them vegetate only in artificially pre- 
pared ground, they have little self-sustaining power, and they 
soon perish when the nursing hand of man is withdrawn from 
them. 
The vine genus is very catholic and cosmopolite in its habits, 
but particular varieties are extremely fastidious and exclusive 
in their requirements as to soil and climate. The stocks of 
many celebrated vineyards lose their peculiar qualities by 
* In a communication lately made to the French Academy, M. Vibraye gives 
numerous interesting details on this subject, and says the appearance of the 
many new plants observed in France in 1871, ‘‘results from forage supplied 
from abroad, the seeds of which had fallen upon the ground. At the present 
time, several Mediterranean plants, chiefly Algerian, having braved the cold 
of an exceptionally severe winter, are being largely propagated, forming exten- 
sive meadows, and changing soil that was formerly arid and produced no 
vegetable of importance into veritable oases.” See NATURE, Aug. 1, 1872, 
p. 268. We shall see on a following page that canals are efficient agencies in 
the unintentional interchange of organic life, vegetable as well as animal, 
between regions connected by such channels, 
