( 50 ; 



Examination of the Views adopted by Liebig on the Nutrition of 

 Plants. By William Seller, M.D., one of the Vice- 

 Presidents of the Botanical Society of Edinburgh. Com- 

 municated by the Author.* 



The onward career of analysis, from mineral nature to the 

 study of organic bodies, has nearly broken down the barrier 

 between Chemistry and Vegetable Physiology. The publica- 

 tion of Liebig's work " On the Chemistry of Agriculture and 

 Physiology," marks an era of surpassing import in Chemical 

 Science, as well as in the Philosophy of Plants. It is not to 

 any unexpected novelty in its facts or principles that that 

 work owes its excellence. It is because it discloses, in one 

 unbroken view, the growing evidence of the unity of the 

 operations of Nature, — because it sets the mind at ease with 

 itself on many matters difi&cult of belief — because it affords 

 the testimony of a competent judge, one of the acknowledged 

 masters in the great art of interpreting Nature, to the re- 

 ality of many unlocked for links between separate provinces 

 in the economy of the natural world — and because it thereby 

 prepares us patiently to contemplate relations, which, at first 

 sight, seem too remote from the ordinary line of our thoughts 

 to come within the compass of the human faculties, and even 

 too daring to obtain our unqualified faith. 



But Liebig's work is not a treatise whose object is to re- 

 solve points of difficulty in the economy of plants. It is 

 rather an appeal in behalf of the trust-worthiness of certain 

 great principles of investigation, the value of which in guid- 

 ing the onward progress of physiology has been too little 

 recognised in past times. His views turn on particular 

 methods of inquiry as necessarily leading to the truth ; while 

 it may be feared that his propositions occasionally partake 

 of the character of assumptions made to illustrate the appli- 

 cation of his principles, rather than of inferences, in the 

 exactness of which an implicit reliance can be placed. 



My object at present is to examine the views adopted by 



* Read to the Society on IStli February 1845. 



