CHAPTER III. 



VEGETATION. 



As soon as it has escaped from the integuments of 

 the seed, the young plant becomes capable of abstrac- 

 ting from the atmosphere and the earth, the nutriment 

 necessary to its complete developement ; and our next 

 enquiry relates to the food which it absorbs, and to the 

 agents by which its growth is affected. By the aid of 

 chemistry the soil and the Atmosphere have been ana- 

 lyzed, and when we compare the ingredients of which 

 they are composed, with those which enter into the 

 composition of vegetables, it will be found, that the lat- 

 ter do not select the principles which the former con- 

 tain in the greatest abundance. Carbon, oxygen and 

 hydrogen, the two last by their union forming water, 

 constitute the bulk of most plants. Yet it appear?, 

 that the proportion of these and the other ingredients, 

 is various in different plants, and hence it is obvious, 

 that they would not grow with equal luxuriance in the 

 same soil, sustained by the same food, and exposed (o 

 the same privations. Hence we learn, why some veg- 

 etables flourish in clayey, some in flinty earth, while 

 others thrive better in a calcareous soil than in either 

 of these : why some are found invariably on the mar- 

 gin of the sea, while others shun, as the pestilence of 

 death, the vapours of the " salt sea foam.'' And hence 

 we learn, why some thrive only in water, others on 

 the dry and sandy plain, why some grow hixariantly in 



