INFLUENCE OP WATER UPON NUTRITION. 89 



The experiments of M. de Saussure have always been 

 made upon volumes of air, exceeding from thirty to forty 

 times those of the fruits ; and by this means the heating 

 action of the sun was much diminished. 



The results of the experiments of M. Berard are all 

 applicable to the ripening of fruits, which was the par- 

 ticular object of his attention ; whilst those of M. de 

 Saussure relate chiefly to their growth. The first con- 

 siders the changes they undergo when detached from the 

 tree ; and if he sometimes performed his experiments upon 

 green fruits, their action under his small receivers was 

 like that of dead bodies. The second analyzed the phe- 

 nomena of their growth ; and it is not astonishing, that 

 the two should have obtained different results. 



ARTICLE IV. 



The Influence of Water upon Nutrition, 



Water influences vegetation not only by the nutritive 

 principles furnished to plants by its decomposition, but by 

 means wholly physical, and which we shall first consider. 



The first effect of water upon a soil appropriated to 

 vegetation is, to moisten and divide the earth, and conse- 

 quently to favor the extension of roots, the introduction of 

 air, and the developement of seeds. 



The second is that of conveying to the seed the first 

 aliment required by it, oxygen, which that liquid always 

 holds in solution in a greater or less degree, and which is, 

 as I have already observed, the principal agent in germi- 

 nation. 



The third office performed by water is that of dividing 

 the manure applied to the soil, of dissolving some portions 

 of it, and conveying them to the organs of the plants in a 

 state fitted for their digestion and nourishment. 



All kinds of water are not equally suitable for this pur- 

 pose; rain water, which is the purest and contains the 

 most air of any, is also the best for supplying the wants of 

 plants. Generally speaking, those streams which have 

 their rise in granitic or primitive calcareous mountains, 

 are favorable to vegetation ; but it is necessary that they 

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