Life and Wrilinga of Theodore de Saussure. 13 



mineral chemistry; but the excellent means of observation 

 afforded by the discovery of pneumatic chemistry, and the 

 power of distinguishing and characterising definitely the ele- 

 ments which constitute organised beings, remained still to be 

 applied to the study of these bodies. This presented a vast 

 field of research, which fifty years of labour, in an age when 

 workers have multiplied in myriads, have very far from ex- 

 hausted, and which, at that time, was scarcely entered upon. 

 Happy the investigator who, upon entering on his career, se- 

 lects a subject at once vast and circumscribed, on which all 

 his energies may be exerted without being disseminated, and 

 with no fear of too speedily exhausting the matter ! His 

 talents and perseverance are then the certain guarantees that 

 he will arrive at useful results, and that success will crown his 

 efforts. Such was the lot of Theodore de Saussure. Among 

 organised bodies, he chose plants as the objects of his 

 scientific researches, and applied himself, in particular, to dis- 

 cover, by means of experiment, the influence which the media 

 in which they live exercise on their existence and composi- 

 tion, and also the part which chemical forces must take in the 

 various phases of their development. With the exception of 

 a very small number of accessory investigations, the whole scien- 

 tific life of Theodore de Saussure was devoted to the accomplish- 

 ment of this object ; and it may be affirmed, without any ex- 

 aggeration, that he has of himself done more to advance vege- 

 table physiology than all the other labourers, numerous though 

 they be, in the same field, whom the publication of his dis- 

 coveries induced to enter on the path which he opened up and 

 rendered of ready access. 



Before his time there existed, indeed, a few observations by 

 Priestley, Senebier, and Ingenhouz on the relations of plants to 

 the surrounding atmosphere ; but these philosophers had gone 

 no further than to establish the decomposition of carbonic acid 

 by the leaves under the influence of the solar light, without 

 drawing from this fact any conclusion as to the mode of nutrition 

 of vegetables. Almost everything, therefore, remained to be 

 done ; and Theodore de Saussure had the perseverance to work 

 seven years in silence, that his work might not be published 

 till it should be complete. And here I cannot help expressing 



