66 Dv Seller on the Nutrition of Plants. 



from the soil. He knew that 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 affir;ming 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 sen- 

 tence, 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 con- 

 tains more ammonia than the wood from which it forms ; and 

 this difference he ascribes to the effect produced 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 

 substances 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 unchallenged, even if the progress of inquiry shall 

 graft the views of Mulder on those of Liebig, namely, that 

 certain azotised substances 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 mani- 

 festly cannot be otherwise, than as yeasts contribute to fer- 

 mentation. 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 re-convert this or- 

 ganic matter into its original mineral condition. Thus, from 

 air, water, and a little soil, all organic bodies are made. 



Sic modo quBc fucrat rudis et sine imagine tellus 

 ludult ignotas liominum conversa figuras. 



And thus modern science realizes the happy conjecture of 

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

 elements of the ancients are the elements of organic nature 



* Recherclies Cbemiqucs siu: la Vegetation, par Theod. De Saussure, 

 p. 1S5. 



