68 VEGETABLE POWER OF ACCOMMODATION. 



The forage imported for the French armj in the war of 18T0- 

 1871 has introduced numerous plants from ]S'orthem 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 economical, effect on the flora of 

 that country.* 



The Canada thistle, Cnicus a/vensis, which is said to have ac- 

 companied 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 

 sMn of an American bird. 



Vegetable Power of Accommodation. 



The cereals and other vegetables which, so far as we know 

 their history, seem to have been longest the objects of human 

 •care, can, by painstaking industry, be made to grow under a 

 great variety of circumstances, 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 prepared ground, they have little seK-sustaining 

 power, and they soon perish when the nursing hand of man is 

 withdrawn from them. 



The vine g enus is very cathohc and cosmopoHte in its habits, 

 but particular va/rieties are extremely fastidious and exclusive 

 in their requirements as to soil and chmate. The stocks of many 

 celebrated vineyards lose their peculiar qualities by transplanta- 

 tion, and the most famous wines are capable of production only 

 in certain well-defined and for the most part narrow districts. 

 The Ionian vine, which bears the httle stoneless grape known in 



* 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 vege- 

 table of importance into veritable oases." See Nature, Aug. 1, 1873, p. 263. 

 We shall see on a following page that canals are eflScient agencies in the unin- 

 tentional interchange of organic life, vegetable as well as animal, between 

 regions connected by such channels. 



