iipon Native Vegetables: G5 



score of moistness. Depth, too, of soil ought to be taken into 

 account ; but that circumstance will be admitted to be of no vi- 

 tal moment by him who adverts to the admirable manner in 

 which roots adapt themselves to existing circumstances. So 

 marvellous sometimes is the manner wherein they do so, that lie 

 mif^ht ahiiost be excused, who should ascribe to vegetables a 

 power of observation and reflection. 



The earths are absorbed by vegetables but seldom, and iii 

 very small quantities ; and as the usual mineral constituents of 

 soil, silica, alumina, magnesia, and lime, appear to exist every 

 where over the earth's surface, it may be believed that every 

 soil has as much of each of them as is necessary for the consti- 

 tution of any vegetable. It is also clear that no soil can occur 

 without a certain quantity of moisture and carbonaceous mat- 

 ter, the usual and necessary food of plants. In the next place,- 

 analogy, though far from being a safe guide, may be at leiist 

 attended to. It tt, therefore, to be mentioned, that the limiting' 

 of certain vegetables to certain soils, is favoured by no analogy 

 which can be drawn from animals, who live and prosper in 

 nearly all regions, and do so sometimes under circumstances 

 which might be said to be opposed to the fundamental qualities 

 of their natures *. 



The preceding observations, whether relative to rocks or soils, 

 regard only indigenous vegetables, and perhaps do not by any 

 means apply to those which are in a state of culture. Vegetables 

 are cultivated for the sake of particular parts, as the fruit, root, 

 &c. ; and it may be that luxuriance will be favoured by circum- 

 stances in the rock and soil which do not influence the simple 

 existence and propagation of native species -^. 



Aberdeex, l{)th January 1831. 



• It is mentioned by some authors, that in one or more of the Weslernt 

 Isles, the horse is occasionally fed on lishes. 



. -f yide Prof Jameson's Memoir on soils, &c., in his Illustrations of Cuvier's 

 Theory of the Earth. 



APuir. — juxE 1831. !•; 



