Life and Writings of Theodore de Saussure. 19 



solid matters of plants, and reject the untenable notion, but 

 which had been admitted by many naturalists, in accordance 

 with the experiments of Schr coder, that plants can create all 

 the elements of which they stand in need, even such of them 

 as are inorganic. Theodore de Saussure was the first to point 

 out the importance of the alkaline salts and the phosphates in 

 the culture of the cereal grasses, in accordance with the con- 

 siderable proportion of these salts which the alimentary 

 grains contain. He explained the reasons why the same 

 weight of leaves and herbaceous portions afford more ashes 

 than trunks and branches. Finally, he demonstrated that, 

 with the exception of a small increase, owing, probably, to the 

 dust diffused through the atmosphere, plants which grew in 

 distilled water contain scarcely more ashes than the seeds 

 jfrom which they sprung, and that these ashes were of the 

 same chemical nature ; while the same plants grown in the 

 soil no longer contained in their ashes the salts of the ashes 

 of the seed, but had obviously increased the absolute quantity 

 of saline and earthy matters composed only of other mate- 

 rials. 



Notwithstanding its extent, the analysis I have just given 

 will afford but an imperfect idea of this remarkable book, in 

 which I know not which to admire most, the author's sagacity 

 in the choice of the most conclusive experiments, or his inde- 

 fatigable perseverance in executing them. Accordingly, no 

 sooner did it appear, than it became an authority in science ; 

 and on a detailed analysis of it being given by Bertholet to 

 the Institute, Theodore de Saussure was nominated corre- 

 sponding member of that learned body for the class of che- 

 mistry. Many years afterwards, M. Thenard, when desirous 

 to give an account, in his General Treatise on Chemistry, of 

 the nutrition and growth of plants, commences his exposition 

 in these words : — " Almost all we are about to say will be 

 derived from the excellent work of Th. de Saussure, who has 

 made experiments on this subject which leave nothing to be 

 desired." 



In order to give an idea of the precision and care as to de- 

 tails with which these experiments were conducted, I cannot 

 do better, on my part, than give a description of one of them 

 in the author's own words. 



