86 TRA^'SACTIO^^S and PEOCEEDIXGS of the [Sess. lxii. 



whole, I am of opinion that the plants grown in sterilised 

 earth rooted the best. The steaming of the soil may have 

 had the effect of making nutritive substances more easily 

 assimilable, but the difference was not great. 



As regards the application of nitragin, from which so 

 much was expected, it does not seem to have had any effect 

 whatever either upon the growth of the plant, the develop- 

 ment of the root, or the occurrence on these of nodules. 

 Some of the plants that were inoculated with nitragin had 

 nodules upon their roots, and some had none, but the nodules 

 on the nitragined roots were no more numerous nor were 

 they any better developed than those on the set that got no 

 nitragin. This is a disappointing result, but it is similar to 

 that recorded by Professor Somerville in the paper he laid 

 before the Society last session. In searching for the cause 

 of the failure of this much-advertised material, there are 

 various circumstances that may be considered. 



The bean is not quite so sensitive to inoculation as some 

 other members of the Leguminoste, and Frank describes an 

 experiment with Phaseolus vulgaris in a somewhat similar 

 soil, where nitragin had no effect in increasing the crop 

 whatever, and where, indeed, the plants that were un- 

 sterilised and uninoculated throve best and gained most 

 nitrogen. Frank thought the failure was due to the soil 

 being too poor in organic matter, but if that were so, it was 

 a fatal ol)jection to the use of nitragin, whose chief use and 

 whose greatest virtue was considered to be its capability of 

 enabling leguminous plants to grow on soils poorly supplied 

 with organic matter, and at the bottom of the scale as regards 

 richness in nitrogen. The whole system of growing legumin- 

 ous crops for manurial purposes is to enrich the soil with 

 organic matter, and especially with nitrogen from the air. 

 Soils rich in organic matter are just those that do not 

 require to be treated in that way. 



Again, perhaps the benefit of nitragin was not felt 

 sufhciently because the plants were cut down before 

 maturity, but if that is so, it again tends to nullify the 

 benefits derived from leguminous plants that are grown for 

 green manuring and for increasing the store of nitrogen in 

 the soil, for green manure crops are ploughed up long before 

 they ripen. 



