32 HANDY-BOOK OF HUSBANDRY. 



" part of the vegetable structure. ******* \Ye 

 " have not the slightest reason for believing that the nitrogen of 

 " the atmosphere takes part in the processes of assimilation of 

 *' plants and animals ; on the contrary, we know that many plants 

 " emit nitrogen, which is absorbed by their roots, either in a 

 " gaseous form or in solution in water. But there are, on the 

 *' other hand, numerous facts showing that the formation in plants 

 '' of substances containing nitrogen * * * * takes place in 

 " proportion to the quantity of this element conveyed to their 

 '' roots in the state of ammonia derived from the putrefaction 

 '' of animal matter. ******* l^^ ^g picture 

 " to ourselves the condition of a well-cultivated farm, so large 

 *' as to be independent of assistance from other quarters. On 

 ''this extent of land there is a certain quantity of nitrogen con- 

 " tained both in the corn and fruit which it produces, and in the 

 " men and animals which feed upon them, and also in their ex- 

 '' crements. We shall suppose this quantity to be known. The 

 " land is cultivated without the importation of any foreign sub- 

 '' stance containing nitrogen. Now, the products of this farm 

 " must be exchanged every year for money and other necessaries 

 " of life — for bodies, therefore, destitute of nitrogen. A certain 

 " proportion of nitrogen is exported in the shape of corn and 

 " cattle, and this exportation takes place every year, without the 

 " smallest compensation ; yet after a given number of years, the 

 " quantity of nitrogen will be found to have increased. Whence, 

 " we may ask, comes this increase of nitrogen ? The nitrogen in 

 " the excrements cannot reproduce itself, and the earth cannot 

 *' yield it. Plants, and consequently animals, must, therefore, 

 '* derive their nitrogen from the atmosphere. ****** 

 '^ A generation of a thousand million men is renewed every thirty 

 '' years ; thousands of millions of animals cease to live, and are 

 " reproduced in a much shorter period. Where is the nitrogen 

 " contained in them during life ? There is no question which 

 " can be answered with more positive certainty. All animal bodies 

 " during their decay yield to the atmosphere their nitrogen in the 

 *' form of ammonia. Even in the bodies buried sixty feet under 



