334 



result was due to the fact that in the previous year the upper river- 

 tributaries had in October begun to rise, while in December, ioc6, 

 they were still dried up, and navigation at a standstill. 



The value of the Rubber before shipping, i.e., before duty had 

 been paid on it, probably exceeded £9,500,000. 



W. J. GALLAGHER. 



Gree 



SCIENCE NOTES 



on of Nitrogen by Leguminous Crops. 



le entitled ' Recent Progress in the Practic 



, and the advantages of such 

 e been abstracted : — 



Green manuring improves soils on which it is carried out, in 

 several ways. Vegetable organic matter is added, which not only 

 provides plant food, but also improves the mechanical texture of 

 heavy soils, by lightening it, and making it more open. Further, 

 the organic acids produced in the decomposition of this vegetable 

 matter act as solvents upon the soil constituents, and so render more 

 material available for plant nutrition. 



Probably, however, the most important advantage consequent 

 upon green manuring is that which follows when a leguminous crop 

 such as peas or beans is the 'green manure,' for by means of such 

 a crop, nitrogen from the air is fixed, or converted 'into nitrogenous 

 compounds, and stored up in the soil, where it is available for the 

 succeeding crop. 



About twenty-five years ago, it was ascertained, as the result of 

 experiment, that leguminous plants were able, under some circum- 

 stances, to extract a certain quantity of nitrogen from the air. and to 

 make use of it in their tissue building. The actual method of fixa- 

 tion of the nitrogen by these plants, however, was not understood until 

 1886, when Hellr.egel and WlLFARTH furnished an explanation , 

 as the result of experiments and observations made by them. 1 ne> 

 found that whilst most plants, when raised in sand free from nitrogen, 

 ceased to grow after the reserve nitrogen contained in the seed itselt 

 had been absorbed, seedlings of leguminous plants sometimes to 

 tinued to develop after passing the stage of dependence upon 

 reserve of food. Obviously, the nitrogen these plants daily 

 to their tissues was supplied 'by the air, since it could not be of 

 M - if: : /: iMiKi. and WlLFARTH notcc 

 ever— what had not yet been remarked by other observers 

 all cases where continued growth of the leguminous seedlm 

 occur, nodules or swellings were to be found on the roots, 

 further found that leguminous plants, germinated in sterile 

 soon ceased to grow well, but that if a little water extract of \ 



adde< 



