Dr Seller on the Nutrition of Plants. 65 



But I must draw this long paper to a conclusion. The 

 spirit in which De Saussure so long since studied the vegetable 

 economy, appears to have become dormant among botanists 

 for a good many years. They had too little faith in the con- 

 clusions of modern chemistry to trust to it as an instrument 

 of research. Nor was it surprising, at the commencement 

 of this century, when chemistry was hardly beyond its in- 

 fancy. 



Not a few sciences have suffered severely from the rash trans- 

 fer to them of principles and modes of investigation, of esta- 

 blished success in other kinds of knowledge ; but no science 

 which has to do with matter is entitled to reject the conclusions 

 of chemistry, as to the transmutations of which matter is sus- 

 ceptible. Modern chemistry, in so far as facts are concerned, 

 can undergo no considerable change beyond the attainment 

 of greater exactness. And this is true, even though the whole 

 face of the science and its entire nomenclature should com- 

 pletely alter, as, in the course of time, is very likely to happen. 

 But such an alteration is not a denial of its present facts, 

 or a sinking of its past progress, but merely a change of the 

 aspect under which its conclusions are regarded. Hence, 

 whatever knowledge physiology borrows from chemistry, is 

 not lost by the changes to which that science is subject ; but 

 must remain available in the study of the vegetable economy, 

 though in an altered form. 



Chemistry, in short, must always be the very groundwork 

 of vegetable physiology. It must teach the number, the pro- 

 perties, 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 sui'- 

 prise the world with the announcement of the great bonds of 

 imion 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 cai'bonic acid of 

 the soil and of the atmosphere ; that they fix oxygen and 

 hydrogen from water ; that they derive their saline matter 



VOL. XXXIX. NO. LXXVII.— JULY 1845. E 



