850 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 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 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 earth'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 drawn, 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 declining 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,
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