190 now CROPS GROW. 



Saussure proved that foliage readily yields up saline 

 matters to water. lie placed hazel leaves eight successive 

 times in renewed portions of pure water, leaving them 

 therein 15 minutes each time, and found that by this treat 

 ment they lost J | 16 of their ash-ingredients. The por 

 tion thus dissolved was chiefly alkaline salts; but con 

 sisted in part of earthy phosphates, silica, and oxide of 

 iron. (Recherehes, p. 287.) 



Ritthausen has shown that clover which lies exposed to 

 rain after being cut, may lose by washing more than *| . 

 of its ash-ingredients. 



Mulder, ( Ghemie der Ackerkrume, II, p. 305,) attributes 

 to loss by rain a considerable share of the variations in per 

 centage and composition of the fixed ingredients of plants. 

 We must not, however, forget that all the experiments 

 which indicate great loss in this way, have been made on 

 the cut plant, and their results may not hold good to the 

 same extent for uninjured vegetation, which certainly does 

 not admit of soaking in water. Further investigations 

 must decide this point. 



3. The insoluble matters, or those which become insolu 

 ble in the plant, viz., the sulphate of lime, the oxalates, phos 

 phates, and carbonates of lime and magnesia, the oxides of 

 iron and manganese, and silica, may be deposited as crys 

 tals or concretions in the cells, or may incrust the cell- 

 walls, and thus be set aside from the sphere of vital 

 action. 



In the denser and comparatively juiceless tissues, as in 

 bark, old wood, and ripe seeds, we find little variation in 

 the content of soluble matters. These are present in large 

 and variable quantity only in the succulent organs. 



In bark, (cuticle,) wood and seed envelopes, (husks, 

 shells, chaff,) we often find silica, the oxides of iron and 

 manganese, and carbonate of lime all insoluble substances 

 accumulated in considerable amount. In bran the 

 cuticle of the kernels of cereals- -phosphate of magnesia 



