1846.] JVutritio?! of Plants. 303 



the relations of the elements, which the vital force combines and 

 operates on. And had this truth been more clearly seen, and 

 more firmly held to, at an earlier period, it would not have been 

 left for Liebig at this late day to surprise the world with the an- 

 nouncement of the great bonds of union which so strictly unite 

 the operations of the vegetable economy with those of mineral 

 and of animated nature. For Liebig has not taught much, the 

 rudiments of which are not to be found in De Saussure's work. 

 De Saussure taught, in 1804, that plants fix carbon both from the 

 carbonic acid of the soil and of the atmosphere; that they fix 

 oxygen and hydrogen from water; that they derive their saline 

 matter from the soil. He knew the ammonia is contained in 

 some decomposing vegetable substances; but he does not appear 

 to have arrived at Liebig's conclusion, that it is an essential part 

 of the food of plants; and without affirming what Liebig so 

 pointedly denies, namely, that the extractive matters of the soil 

 are part of the food of plants, he contents himself with saying 

 that these " contribute in a certain proportion to the fertility of 

 the soil;" while he adds, in the same sentence, that "the ashes 

 of these extractive matters contain the same principles as the 

 ashes of plants."* Moreover, De Saussure notices, in particular, 

 that vegetable mould contains more ammonia than the wood from 

 which it forms; and this difference he ascribes to the effect pro- 

 duced on the soil by the numerous insects frequenting it. 



It may be seen, then, that the spirit of the view adopted by 

 Liebig is not of recent date. That plants convert mineral sub- 

 stances into their own substance is a proposition almost coeval 

 with our knowledge of the ultimate composition of air, water, 

 and soil. And all that is essential of this proposition remains un- 

 challenged, even if the progress of enquiry shall graft the views 

 of Mulder on those of Liebig, namely, that certain azotised sub- 

 stances formed in the soil, which have not yet lost their organic 

 character, are indispensable. For if such compounds do aid in 

 the nutrition of plants, it manifestly cannot be otherwise than as 

 yeasts contribute to fermentation. The substance of vegetables 

 is from mineral nature. Plants metamorphose parts of the mineral 

 covering of our planet into organic substance. Animals dissolve 

 the spell bound on it by vegetable life, and reconvert this organic 

 matter into its original mineral condition. Thus, from air, water, 

 and a little soil, all organic bodies are made. 



Thus, modern science realizes the happy conjecture of the an- 

 cients as to the number of the elements. The four elements of 

 the ancients are the elements of organic nature — Air, Water, 

 Earth and Fire, are in tmth the elements of the organic world ; 



*Recherches Chemiques sur la Vegetation, par Theod. De Saussure 

 p. 185. 



