INORGANIC CONSTITUENTS. 177 



Stances. Sea plants seem to be collectors of iodine and bro- 

 mine, just as land plants are of alkalies, such as potash, etc. 



We do not know in what form all of these inorganic con- 

 stituents of plants enter the organs, nor the changes that 

 are wrought upon them in the process of assimilation ; but 

 we may derive from the doctrine of transformations already 

 described, the general nature of the process, and the best 

 idea we can obtain of nutrition and assimilation. 



Thus it appears, that the inorganic constituents of plants 

 are as indispensable to their perfect development, as the car- 

 bon, oxygen, hydrogen and nitrogen. It is therefore of the 

 first necessity, that these substances should be supplied to 

 plants in their proper proportion. The facts developed in 

 this section, relative to the source of the constituents of 

 plants, illustrates the need there is of proper attention to the 

 soil, as it is from the soils that most of the ingredients, ne- 

 cessary to their perfect growth are derived. 



Having now considered the general conditions requisite to 

 the life of veoretables, with the various changes which take 

 place in the phenomena of vegetation, we will here close the 

 subject of Biology ; not because we have exhausted it, but 

 because enough has been advanced, to give the reader a gen- 

 eral idea of the vegetable processes, and of the utility of sup- 

 plying the proper conditions, for the life and growth of those 

 vegetable substances, which are the support of the animal 

 kingdom. Any means, which shall increase these products, 

 are to be sought out with the most diligent care ; we have, 

 therefore, devoted a large portion of succeeding chapters to 

 the subject of the soils, as the most direct means of secur- 

 incr so desirable an end. 



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