COMPOSITION OF EXCREMENTxTIOUS MATTER. 4T 



yields a gummy deliquescent mass, which evolves much ammo, 

 nia on the addition of lime. Ammonia exists in every part of 

 plants, in the roots (as in beet-root), in the stem* (of the maple- 

 tree), and in all blossoms and fruit in an unripe condition. 



The juices of the maple and birch contain both sugar and am- 

 monia, and therefore afford all the conditions necessary for the 

 formation of the azotised components of the branches, blossoms, 

 and leaves, as well as of those which contain no nitrogen. In 

 proportion as the development of those parts advances, the am- 

 monia diminishes in quantity, and when they are fully formed, 

 the tree yields no more juice. 



The employment of animal manure in the cultivation of grain, 

 and the vegetables which serve for fodder to cattle, is the most 

 convincing proof that the nitrogen of vegetables is derived from 

 ammonia. The quantity of gluten in wheat, rye, and barley, is 

 very variable ; these kinds of grain also, even when ripe, con- 

 tain this compound of nitrogen in very different proportions. 

 Proust found French wheat to contain 12-5 per cent, of gluten ; 

 Vogel found that the Bavarian contained 24 per cent. ; Davy 

 obtained 19 per cent, from winter, and 24 from summer wheat ; 

 from Sicilian 21, and from Barbary wheat 19 per cent. The 

 flour of Alsace wheat contains, according to Boussingault, 17*3 

 per cent, of gluten ; that of wheat grown in the " Jardin des 

 Plantes," 26*7 ; and that of winter wheat, 33*3 per cent. Such 

 great differences must be owing to some cause, and this we find 

 in the different methods of cultivation. An increase of animal 

 manure gives rise not only to an increase in the number of seeds, 

 but also to a most remarkable difference in the proportion of the 

 substances containing nitrogen, such as the gluten. 



Animal manure exerts a very complex action on plants, but as 

 far as regards the assimilation of nitrogen, it acts only by the 

 formation of ammonia. One hundred parts of wheat grown on 

 a soil manured with cow-dung (a manure containing the smallest 

 quantity of nitrogen), afforded only 11-95 parts of gluten, and 

 62*34 parts of amylin, or starch ; whilst the same quantity, 



• In an experiment performed at my requp«t in Calcutta, it was found 

 that the fresh juice of the palm tree abounded with ammonia. — Ed. 



