Principles of scientific botany, or, Botany as an inductive science / by J.M. Schleiden ; translated by Edwin Lankester.
- Date:
- 1849
Licence: Public Domain Mark
Credit: Principles of scientific botany, or, Botany as an inductive science / by J.M. Schleiden ; translated by Edwin Lankester. Source: Wellcome Collection.
Provider: This material has been provided by the Royal College of Physicians of Edinburgh. The original may be consulted at the Royal College of Physicians of Edinburgh.
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![recent times this has been called Liebig’s theory of the nutrition of plants: but this is doubly wrong, for in the first place it is no mere theory of the nutrition of plants; and in the second place, it did not originate with Liebig, but with Priestley, and has been gradually de- veloped from his time by the most distinguished experimentalists. Liebig has, indeed, in recent times dwelt upon the importance of its universal recognition, and its relation to the development of a true physiology of plants. He has also done great service by working out the whole problem upon a new method, which was first introduced into the natural sciences by Alexander von Humboldt.* * * § This method con- sists in disregarding at first individual and unarranged observations-}-, and directing attention to the great mass of the phenomena of nature, and where the deficiencies, on account of their great number, attain a minimum of importance, to make calculations, which may be made the basis of points of departure, alike in the estimate of the value of the smallest as of the most isolated part. But on account of the great influence which leading maxims exert, com- prehending, as they do, not only facts and groups of facts, but entire circles of hypotheses, it is above all things necessary that they should be placed on a secure footing, and be susceptible of the strongest possible proof. To the most common examples belong the asserted constancy of the composition of the atmosphere, which Liebig has frequently put for- ward in the fore-ground. “Respiration and combustion consume an immense mass of oxygen, yet the quantity of oxygen in the air re- mains the same; consequently the vegetable world appropriates the carbon of the generated carbonic acid, and again sets free the oxygen.” | It we need proof of this view, we have the following: — A man in the course of a year changes 225 lbs. of carbon into carbonic acid, so that a thousand millions of men would consume 2250 millions of centners § ; for all the animals [| on the earth we may take double this quantity: thus, in the whole, 6750 millions of centners of carbon are yearly burned, which, during the process of burning, would consume 1800 millions of centners of oxygen gas, to which may be added about 400 millions of centners for the burning of coal, j The remaining processes of combus- tion would give 1500 millions of centners of carbon, which consume 4000 millions centners of oxygen. Hence we may take the consumption of oxygen in the course of 300 years at 660 billions of pounds, or about Y^-ths of the present contents of the atmosphere ; and this would fall within the oscillations of our eudiometrical calculations, if we had observed them as accurately 300 years ago as at present. If * The talent which forms an epoch in the history of the natural sciences consists not in the discovery of individual facts or laws, but in the introduction of new ways, the discovery of new methods. f To what absurdity and charlatanerie a dwelling upon individual facts, without a comprehensive view, may lead, has been recently seen, in the most forcible manner, in the work of C. H. Schultz, on the Discovery of the true Food of Plants. J According to Liebig, man consumes daily between 17 and 27 ounces of carbon. § A centner is about 100 pounds.—Trans. | || Boussingault calculates the horse consumes 158] oz., and the cow 141^oz. daily. . ! According to Ure, 6774 millions of centners of coal contain 71 per cent, ot carbon, which is equal to 481 millions of centners of carbon. At my request, my colleague, Professor E. Schmid, had the goodness to calculate](https://iiif.wellcomecollection.org/image/b28043534_0485.jp2/full/800%2C/0/default.jpg)
