hiehigs Organic Chemistry applied to Agriculture. 567 



After bringing forward a fresh supply of well-known facts, Dr. 

 Liebig produces an idea, correct indeed, but familiar to every 

 physiologist as soon as he begins his studies. He says (p. 120), 

 •* From this view" (the view the author had taken cannot be inferred 

 from what precedes), "it is evident how greatly the products of a 

 plant can vary according to the relative proportion of the nourishing 

 matter it receives." This is just the point which renders all modern 

 chemistry useless to vegetable phygiologists ; and this is the reason 

 why physiologists cannot, like Dr. Liebig, conduct experiments on 

 whole acres of forest or meadows, nor in ditches and ponds. They 

 are obliged to make multitudes of exact, tedious, and laborious ob- 

 servations on individual plants ; because their object is to learn the 

 processes of vegetation as they actually go on in such plants, — and 

 not to guess at the probable effects of vegetation on the natural 

 history of the globe. I think Dr. Liebig would have been less ready 

 to heap his invectives upon phygiologists, if he had known that they 

 have not to deal with a salt, composed, according to the constant 

 formula 1 (« -}- ^^) + 1 (c -f- 5^), but to investigate organisation, 

 which is very changeable, and gifted with a great power of adapting 

 itself to circumstances. For, despite of all the formulas of chemistry, 

 there always remains an unknown <r. which we for the present call 

 vital force, notwithstanding the sentence of death pronounced upon 

 it by Dr. Liebig. But I, this moment, perceive that I have wronged 

 him. The great chemist, who has in his pocket all explanations 

 ready made, who, at page 18, is quite certain that plants decompose 

 carbonic acid, and at page 60 thinks, that this is extremely improba- 

 ble, feels on a sudden (p, 121) an utter consternation at discovering 

 the miraculous effect of this vital force, which is able to produce a 

 thing that no chemist can imitate with the most powerful galvanic 

 pile, although it is nothing more than a simple chemical decomposi- 

 tion, namely, that of carbonic acid in plants, which has once more 

 obtained his approbation. But, Sir, did you not feel, when you were 

 writing this passage, what a silly figure you must cut in the eyes of 

 physiologists, after having heaped upon them so many opprobrious 

 terms We find that 999 thousand parts of the vital functions of 

 vegetation are inexplicable, but we perceive that the last thousandth 



4 c 



