THEORY AND PRACTICE. 69 



cotemporaneously with the announcement of a great 

 doctrine, the introduction and use of Guano during 

 the lifetime of Liebig is one of the happiest and most 

 remarkable. If some great physical event had testified 

 to men's bodily senses the motion of the Earth round 

 the Sun, and the steady centricity of that luminary, 

 during the exact life-time of Copernicus or Galileo; 

 or if some conceivable reflection of the earth's surface 

 in the deep azure of heaven, had exhibited to men's 

 wondering eyes the outline of the great American 

 continent looming along its obverse hemisphere, just 

 as Columbus was collecting subscriptions for his first 

 equipment in quest of it, they would not each have 

 furnished a more triumphant vindication of the achieve- 

 ments of those master-minds, during their own exist- 

 ence upon earth, than that which the more fortunate 

 Professor of Giessen has been destined to witness. 

 No sooner had the persecuting infidelity of man (the 

 same in every age) begun to crucify his great theory 



of THE NUTRITION OF PLANTS FROM THE ATMO- 

 SPHERE, than the use of Guano and of inorganic 

 manures began to give it proof. 'Burn a plant, 

 whether it be an Oak-tree or a stalk of Clover,' (for 

 so the assertion of the great Analyst may be briefly 

 epitomized) 'and the trifling ash it leaves will show 



