NOURISHMENT OF PLANTS. 21 



life, this, their general history, remains essentially un- 

 altered. 



The divine spirit of Life, which eflfects these 

 changes and calls forth the phenomena of exist- 

 ence in the vegetable world, is in its essence entirely 

 unknown to us. We give it, indeed, the name of 

 vital power, but gain thereby no clearer appreciation 

 or knowledge of its nature. Its operations are con- 

 ducted in a manner so replete with mystery, as to 

 render it apparently improbable that the speculations 

 and inquiries of the human intellect wall ever be con- 

 verted into full and distinct knowledge upon this point. 

 We feel, it is true, the rushing of the vital current in 

 the joy which pervades our being when in spring 

 it bursts the buds and covers the earth with showers 

 of blossoms, as also in the melancholy which attacks 

 us when in autumn the withering of the leaves 

 announces its withdraw^al; but whence it comes, 

 whither it goes, and by w^hat magic it evokes the 

 wonders of the vegetable world, we are altogether 

 uninformed. That which it produces, and that from 

 which it brings this forth, are alone cognizable by 

 our senses. 



Two paths stand open to the inquirer, by means 

 of which he may penetrate, up to a certain point; 

 into the mysterious laboratory of vegetable life : — 

 1st. That of observation, w^hich, by the aid of the 

 microscope especially, has led to a very accurate 

 knowledge of the structure of plants, and of those 

 changes in the fonn of their separate parts which 



