125 



Proceedings of Societies. 



BOTANICAL SOCIETY OF EDINBURGH. 



February 13, 1845. — Dr. Douglas Maclagan, President, in the chair. 



Dr. Herman Hoffmann, Giessen, was elected a foreign member of 

 the Society. 



Various donations to the library and museum were announced, and 

 the following communications were read : — 



1. Dr. Seller read a paper, entitled, "Examination of the views 

 adopted by Liebig on the Nutrition of Plants." He contrasted Lie- 

 big's view of the mineral nature of the food of plants, with that which 

 represents their food as organic. He traced out the consequences 

 deducible from this last hypothesis, as affecting not merely the vege- 

 table, but the animal kingdom also ; the latter being ultimately sus- 

 tained solely by vegetable substances. He showed that, whereas the 

 view adopted by Liebig nowise restricts the duration of the organized 

 kingdoms, as long as they remain exempt from the influence of de- 

 structive agencies from without, the opposite view involves the con- 

 clusion, that the whole of organic nature is hastening rapidly to dis- 

 solution from inherent causes, and he affirmed, that were certain data 

 somewhat more carefully considered, the period of the final extinction 

 of plants and animals, in accordance with this hypothesis, might be 

 pretty nearly determined. He regarded this question as one not 

 merely of high interest in itself, but as bearing expressly on the solu- 

 tion of the problem, whether the food of plants be organic or mineral. 



Dr. S. calculates the annual conversion of the carbon of organic 

 matter into inorganic carbonic acid, at not less than six hundred mil- 

 lions of tons ; and infers, on the most favourable aspect of the amount 

 of soil over the earth's surface, that such an annual loss could not be 

 withstood beyond six thousand years ; and, on a less exaggerated as- 

 sumption of its amount, probably very near the truth, that the waste 

 would absorb the whole of the existing organic matter of the soil in 

 about seven hundred and forty years. 



Dr. S. contends that the truth of these conclusions remains unal- 

 tered, even if it be conceded that much of the carbon of plants is 

 drawn, not from the organic matter of the soil, but from the inorganic 

 carbonic acid of the atmosphere, unless some inorganic source of their 

 hydrogen and oxygen be at the same time admitted. He, therefore, 

 regards Liebig's view of the inorganic nature of the food of plants as 

 supported, not merely by many special facts — for example, by the 

 increase of the organic matter of the soil, often observed during the 

 growth of plants, — but also by the general view of the earth's surface 



