270 



SCIENCE OF AGRICULTURE. 



Part II. 



ture in gardens, fields, or timber-plantations ; and indirectly by accliniatiDg and final 

 naturalisation of many species, by the influence of winds and birds in scattering their 

 seeds. The vine and the fig are not indigenous to France, but are now naturalised there 

 by birds. In like manner the orange is naturalised in the south of Italy. Many her- 

 baceous plants of the Levant are naturalised both in France and Britain ; some, as the 

 cabbage, cherry, and apple, were probably naturalised during the subjection of England 

 to the Romans. The narrow-leaved elm was brought from the Holy Land during 

 the crusades. Phaseolus vulgaris, and impatiens balsamina were brought originally 

 from India ; and datura stramonium, which is now naturalised in Europe, was brought 

 originally from India or Abyssinia. Buckwheat and most species of corn and peas 

 came also from the East, and along with them several plants found among corn only, 

 such as centaurea cyanus, agrostemma githago, raphantis raphanistrum, and myagrum 

 sativum. The country from whence the most valuable grasses migrated is not known. 

 Bruce says he found the oat wild in Abyssinia, and wheat and millet have been found 

 in a wild state in hilly situations in the East Indies. Rye and the potatoe were not 

 known to the Romans. The country of the former Humboldt declares to be totally 

 unknown. 



1735. The greatest refinement in culture consists in the successful formation of artificial 

 climates for the culture of tropical plants in cold regions. Many vegetables, natives of 

 the torrid zone, as the pine apple, the palm, &c. cannot be acclimated in temperate 

 countries. But by means of hot-houses of different kinds they are grown even on the 

 borders of the frozen zone to the highest degree of perfection ; and in Britain some of 

 the tropical fruits, as the pine and melon, are brought to a greater size and better flavor 

 than in their native habitations. Casting our eyes on man, and the effects of his indus- 

 try, we see him spread on the plains and sides of mountains, from the frozen ocean to 

 the equator, and every where he wishes to assemble around him whatever is useful and 

 agreeable of his own or of other countries. The more diflSculties to surmount, the more 

 rapidly are developed the moral faculties ; and thus the civilisation of a people is almost 

 always in an inverse ratio with the fertility of the soil which they inhabit. What is the 

 reason of this ? Humboldt asks. Habit and the love of the site natal. 



Sect. IV. Characteristic or Picturesque Distribution of Vegetables. 



1 736. The social and antisocial habits of plants is one of their most remarkable charac- 

 teristics. Like animals they live in two classes : the one class grows alone and scattered, 

 as solanum dulcamara, lychnis dioica, polygonum bistorta, anthericum liliago, &c. The 

 other class unites in society, like ants or bees, covers immense surfaces, and excludes other 

 species, such as fragaria vesca, vaccinium myrtillus, polygonum aviculare, aira canescens, 

 pinus sylvestris, &c. Barton states that the mitchella repens is the plant most extensively 

 spread in North America, occupying all the ground between the 28 and 69 of north 

 latitude. The arbutus uva ursi, extends from New Jersey to the 72 of latitude. On 

 the contrary, gordonia, franklinia, and dionaea muscipula are found isolated in small 

 spots. Associated plants are more common in the temperate zones than in the tropics, 

 where vegetation is less uniform and more picturesque. In the temperate zones, the 

 frequency of social plants, and the culture of man, has rendered the aspect of the country 

 comparatively monotonous. Under the tropics, on the contrary, all sorts of forms are 

 united ; thus cypresses and pines are found in the forests of the Andes of Quindiu, and of 

 Mexico; and bananas, palms, and bamboos in the valleys, {fig. 243.) But green meadows 



and the season of spring are wanting in the south, for nature has reserved gifts for every 

 region. The valleys of the Andes," Humboldt observes, "are ornamented with banana* 



