FOOD OF PLANTS^* GENERAL. 475 



easily shown by a great example. AcoBking to official documents, the 

 stock of cattle in France in the year 1844 comprised of large animals 

 (bulls, oxen, cows, stallions, geldings, mares, and mules) 10,709,391 st. ; 

 of small animals (donkies, calves, foals, pigs, sheep, and goats) 

 = 30,859,454 st. The daily loss of organic matter may be calculated 

 as 1 1 Ibs. in the first, and 3 Ibs. in the second class of animals, so that 

 for their nourishment in one year about 76,789 millions of Ibs. of or- 

 ganic substances are required, a quantity equal to about six times the 

 weight of the whole of the stock of cattle. If we suppose that the ex- 

 isting quantity of organic matter is 600 times as great as that which 

 represents the whole stock of cattle, yet would the loss during the 

 nourishment of the cattle of France result in a perfect desert in the 

 course of a single century. 



It results then from these facts that the organic substances which 

 are burned and serve as food to animals, are at least half destroyed, 

 and that in 100 years they would be reduced to nothing. But we 

 have, both in the history of the earth and in the history of man, in the 

 former from geological period to period, and in the latter from century to 

 century, evidence not of a decrease but of an increase of organic life upon 

 the surface of the earth. There must, therefore, be continually going on 

 a conversion of inorganic matter into organic combinations. From phy- 

 siological researches* it appears perfectly certain that this cannot go on 

 in the bodies of animals. Neither do we know of any facts in the whole 

 of nature that would lead us to conclude that inorganic substances in* 

 dependent of an organism could be changed into organic compounds. 

 Whilst on the contrary all experience proves that the organic substance 

 is unceasingly passing over into inorganic combinations. The only in- 

 ference from all this is, that plants convert inorganic into organic 

 substances ; and this we must hold as a first great law of nature. The 

 only universally diffused inorganic compounds which can be taken up 

 by plants in order to assimilate carbon, oxygen, hydrogen, and nitrogen, 

 are the carbonic acid gas, water, and carbonate of ammonia of the at- 

 mosphere, and from these must the vegetable world be almost exclusively 

 supplied as the materials of their nutrition, f This law concerns not 

 alone the vegetable world in general, but has an important special ap- 

 plication in the culture of plants. This will be seen when we look at 

 the production of manure according to the foregoing calculations ; and 

 further, reflect that on a well-managed estate a considerable part of the 

 produce, as corn, cheese, butter, wool, &c., is annually taken away, re- 

 turning no manure to the soil, and that the organic substance remaining 



* See Valentin, Liebig, Mulder, &c. 



f This thought seems to have floated darkly before the mind of Liebig, when he 

 said " a primitive humus cannot be granted," a proposition to which the sense of the 

 words would give no signification. Under every circumstance, before an organism 

 could be present in the formation of the earth, inorganic must have passed into organic 

 substances, whether as an organic embryo, or as an organic substance from which the 

 embryo would be first developed. As we are ignorant on this point, and are as likely 

 to remain so, as we are with regard to the nature of organic life in the system of Sirius, 

 so is it foolish to assert that either this or that combination could not exist provided it 

 is chemically possible. It may be conceived that, through a special process, dextrin 

 and protein were first formed ; and that, during the decomposition of these substances, 

 humus, or even that, favoured by this process of decomposition, the first plant-cell was 

 formed. Thus we might have a primitive humus. With this explanation, the view 

 that no dextrin and no protein are developed independent of an organism may be re- 

 ceived, as well as the view now universally held by the most distinguished naturalists, 

 that no specifically definite organism can originate but in a maternal cell, although such 

 might once have originated on the earth's surface. 



