266 GEOGRAPHICAL DISTRIBUTION OF PLANTS. 



shire which are not met with ao;ain until we reach the 

 shores of the Arctic Sea. 



The peculiarities of the climate of Canada and Rupert's 

 Land may be in part shown by reference to a few of the 

 plants usually cultivated for food. The vine would thrive 

 with the summer heat of Fort Simpson were the season 

 long enough ; but the September and October heats, which 

 are required to ripen its fruit, do not occur in any district 

 of Rupert's Land ; and the grape is destroyed by the 

 severe night frosts which are frequent in autumn even in 

 so low a parallel as the north shore of Lake Superior. The 

 conditions essential to the due growth of the vine, mentioned 

 by Meyen*, do not extend in the basin of the St. Lawrence 

 beyond the 43rd parallel, while on the Rhine wine is a 

 profitable production up to the 51st. 



Maize is a plant which thrives best in the dampest and 

 hottest tropical climates, where it brings forth eight hun- 

 dred-fold. Its culture extends into temperate regions, but 

 with a greatly diminished yield ; and it is cultivated near 

 its northern limit only as a green vegetable, the grain seldom 

 ripening, and being eaten in its milky state. This is its 

 condition in most parts of Great Britain, when reared in 

 the open field. On the western shore of Europe it is not 

 cultivated beyond 46°, though in the valley of the Rhine 

 it extends to 49° north lat. In South America, on the 

 Chili coast, it is planted as low as 40° south lat. ; and on 



* This author states that the culture of the vine is regulated more 

 by the length of summer than by its high temperature, though the 

 latter is also an element in the proper ripening of the grape. It will 

 succeed, he says, under every tropical heat, provided the atmosphere 

 be not too moist. It thrives well under a mean heat of 60° Fah. ; 

 it ripens wilh a lower mean heat of 48° Fah., and a summer heat of 

 67° Fah., bvit the juice contains less sugar and yields less alchohol. 

 (Meyen, Geogr. of Plants.) 



