Distribution of Plants, 529 



instance. In like manner, borne along by the currents, fruits 

 and seeds belonging to the West Indian islands are cast upon 

 the Hebrides and the coast of Norway, during storms from 

 the south-west, as cocoa nuts, gourds, the fruit of y^cacia 

 scandens, Piscidia Erythrina, and Anacardium occidentale. 

 But these examples, though affording a slight argument, are 

 far from proving that the whole vegetable world was thus 

 dispersed. 



By our commercial relations with distant countries, we 

 have received many foreign productions : thus the peach, 

 nectarine, cherry, vine, and almost all our fruits, are exotic, 

 the greater part being original natives of Armenia and the 

 most central parts of Asia. The cherry, we are told by Pliny, 

 was first brought into Italy by Lucullus, after his victory over 

 Mithridates, from Pontus ; and, 120 years after, was known 

 in Britain. (Pliny, Nat, Hist.^ b. iv. c. 21.) The same author 

 also relates that quinces were brought originally from Crete, 

 and walnuts from Asia Minor. Even the different species of 

 grain, which constitute one of the chief sources of our wealth, 

 are original natives of central Asia. Bruce supposed that 

 Abyssinia was the native country of the oat, from their luxu- 

 riance and size in that country ; being equal in height to a 

 man, and the stalks near an inch in diameter. (Head's Life 

 of Bruce.) 



I will now mention a second hypothesis, which has been 

 thought sufficient to account for the universal dispersion of 

 plants : that they originated from primitive centres situated in 

 different parts of the world, and embracing different species, 

 which, by continued progression, became blended, and no 

 longer peculiar to their original locality. But neither is this 

 theory unexceptionable. The causes which influence the dis- 

 tribution of plants are so complicated, that it is difficult to 

 offer a probable opinion upon the subject. We often find in 

 most distant countries similar species, whilst the floras of 

 adjoining provinces are frequently altogether dissimilar. It 

 is obvious that their position depends upon the peculiar nature 

 of the soil : thus, wherever salt marshes are found, alkaline 

 plants, the chenopodiums, salsolas, atriplexes, salicornias, &c., 

 are almost certain to occur. Mountains exercise great influ- 

 ence over the distribution of vegetables : we find the same, or 

 similar, productions upon mountains of the same geological 

 structure, though separated by half the globe. By this as- 

 sertion, I, of course, must be understood to mean at the 

 same (or nearly so) altitude above the level of the sea ; or, 

 perhaps, more correctly, below the snow line, combined with 

 climate and atmospheric temperature. Thus, upon the chain 



Vol. v. — No. 28. mm 



