350 Botanical Society of Edinburgh. 



PROCEEDINGS OF LEARNED SOCIETIES. 



BOTANICAL SOCIETY OF EDINBURGH. 



Feb. 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 Liebig'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 vegetable but the animal kingdom also, the latter 

 being ultimately sustained solely by vegetable substances. He showed 

 that, whereas the view adopted by Liebig nowise restricts the dura- 

 tion of the organized kingdoms, as long as they remain exempt from 

 the influence of destructive agencies from without, the opposite view 

 involves the conclusion, that the whole of organic nature is hastening 

 rapidly to dissolution 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 

 h3'pothesis, might be pretty nearly determined. He regarded this 

 question as one not merely of high interest in itself, but as bearing 

 expressly on the solution of the problem, whether the food of plants 

 be organic or mineral. 



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

 matter into inorganic carbonic acid at not less than 600 millions of 

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

 over the eartli's surface, that such an annual loss could not be with- 

 stood beyond 6000 years ; and, on a less exaggerated assumption of 

 its amount, probably very near the truth, that the waste would ab- 

 sorb the whole of the existing organic matter of the soil in about 740 

 years. 



Dr. Seller contends that the truth of these conclusions remains 

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

 is drawai, not from the organic matter of the soil but from the inor- 

 ganic 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 ex- 

 ample, by the increase of the organic matter of the soil, often ob- 

 served during the growth of plants, — but also by the general view of 

 the earth's surface just taken, because there is nothing in its aspect 

 to warrant the idea that its means of maintaining the organic king- 

 doms are decUning with the rapidity indicated in the statements 

 just made. 



Dr. Seller next examined Liebig's views of ammonia ; 1st. as the 

 sole source of the nitrogen of plants, and thereby of animals ; 2nd, 



