96 THE WORLDS LUMBER ROOM. 



distinctly visible. No effect seemed to have been produced 

 on the glass or gypsum ; but that, after all, might only mean 

 that it was as yet too slight to be perceptible. 



Smooth pieces of limestone are often found in meadows 

 with their surfaces covered by a perfect network of small 

 furrows, which on careful examination are seen to correspond 

 exactly with some tiny root or rootlet. 



Lupins are especially active in decomposing mineral 

 matter, and for this reason they are sometimes, as in the 

 Azores, planted with corn and ploughed in as manure. 

 Three lupins planted in powdered sandstone have been 

 found to take up three -fifths of a grain of mineral matter ; an 

 equal number planted in powdered basalt took up three- 

 quarters of a grain. Three peas took up rather less basalt 

 and much less sandstone, and buckwheat, vetches, wheat, 

 and rye, considerably less of both ; but all showed a marked 

 preference for the basalt. 



Their work did not, however, end with what they had 

 absorbed, for it was found that they had dissolved more 

 than they had used, and the soil was, therefore, so much the 

 better fitted for the support of other plants. 



All plants require sulphur, phosphorus, flint, iron, potash, 

 soda, lime, magnesia, and chlorine, for their proper develop- 

 ment; and though they may take but an infinitesimal amount 

 of some of these, all are equally necessary, and the absence of 

 any one would prove fatal. Some take more of one and 

 some more of another, and even the different parts of the 

 same plant may take the minerals in different proportions. 

 Thus grasses and all the varieties of corn take up much more 

 flint than turnips and cabbages do ; and while the ash of 



