262 THE FARMER AT HOME. 



Indians use it for poisoning the points of their arrows, which preserve 

 their venom for a long time. The workmen employed in felling these 

 trees first build a fire round the trunks, in order to make the juice 

 evaporate, and cover their eyes with gauze ; but, notwithstanding 

 these precautions, they are subject to be incommoded with the dust. 

 The accounts, however, which represent it as dangerous to sleep in 

 the shade, or to come in contact with the rain which has fallen upon 

 this tree, are highly exaggerated. The inhabitants of Martinique 

 formerly burnt entire forests of the manchineel, in order to free their 

 dwellings from its presence. 



MANGEL WURZEL. Mangel Wurzel, or the root of scarcity, 

 is a root much celebrated as food for cattle. It is a species of beta. 

 It is a biennial plant ; the root is large and fleshy, sometimes a foot 

 in diameter. It rises above the ground several inches, and is thick- 

 est at the top, tapering gradually downwards. The color of the roots 

 vary ; being white, yellow, and red. It is good fodder for cows, and 

 for rabbits, and produces great plenty of leaves, which are very palat- 

 able and wholesome for cattle. It is chiefly cultivated in Germany. 



MANURES. All agents used by agriculturists to preserve or 

 restore the productiveness of the soil, are properly called manures. 

 All soils, after being cultivated and subjected to the exhausting influ- 

 ence of continual harvests, become deficient in mineral and organic 

 elements, which must be replaced artificially, or total barrenness 

 will ensue. Manuring is the process by which this end is accom- 

 plished, and for it there is no substitute. If the supply be less than 

 the crops require, the soil increases in barrenness ; if it just replaces 

 what has been removed by the crops, the fertility remains the same ; 

 if more be added than the crops require, the fertility of the land is 

 increased. 



The whole science of manuring consists in supplying to the soil 

 those indispensable elements which have become exhausted. The 

 richest manure may be applied to a failing soil, and if it lacks a par- 

 ticular element which the crops require, and which the soil does not 

 contain, the soil grows barren, notwithstanding the manuring. Farm- 

 yard manure probably contains the greatest number of elements 

 necessary to fertility ; but particular plants require special manures. 

 The remains of plants, together with the excrements and carcases of 

 animals, if returned to the soil before decomposition, must contain all 

 the mineral, organic, and gaseous elements, which the plants derived 

 from the soil or the atmosphere. These must pass through the differ- 

 ent processes of decomposition, before they assume their original gas- 

 eous and earthy forms, and become available for the food of plants. 



Manures opera-te beneficially on the soil in several ways. First, 

 by serving directly in some instinces as the food of plants. Second, 

 by causing chemical changes in the soil, by which other substances 

 are prepared to be taken up as nutriment by their roots. Third, by 



