29 



State Agricultural College, devoted between two and three years to 

 the investigation at Rothamsted. The conditions of the experiments, 

 and the results obtained up to that date, are fully described in the 

 papers in the Fhilosopldcal Transactions for 1859, and in the Journal 

 of the Chemical Society in 1863, already referred to. Table VIII 

 (p. 28) summarises the results obtained. 



The upper part of the table shows the results obtained in the experi- 

 ments in which no combined nitrogen was supplied beyond that con- 

 tained in the seed sown. The growth was in all cases extremely re- 

 stricted ; and the figures show that there was in no case, whether of 

 Graminese, Leguminosse, or buckwheat, % gain indicated by as much as 

 3 milligrams of nitrogen. There was in most cases much less gain, or 

 a slight loss. 



The lower part of the table shows the results obtained when the 

 plants were supplied with known quantities of combined nitrogen, in 

 the form of a solution of ammonium sulphate applied to the soil. The 

 actual gains or losses rauge a little higher in these experiments, with 

 larger quantities of nitrogen involvtid ; but they are always represented 

 by units of milligrams only, and the losses are higher than the gains. 

 Further, the gains, such as they are, are all in the experiments with 

 the Gramineae, whilst there is in each case a loss with the Leguminosee 

 and the buckwheat. 



It should be stated that the growth was far more healthy with the 

 Gramineae than with the Leguminosse, which are even in the open field 

 very susceptible to vicissitudes of heat and moisture, and were espe- 

 cially so when inclosed under glass sliades. It might be objected, 

 therefore, that the negative results with the Leguminosse are not so 

 conclusive as those with the Graminese. Nevertheless, we do not hesi- 

 tate to conclude from our own experiments, as Boussingault did from 

 his, that the evidence is strongly against the supposition that either 

 the Graminese or the Leguminosse assimilate the free nitrogen of the 

 atmosphere. 



Recapitdlation. 



In the foregoing re'smne of mostly previously recorded facts, we 

 have shown the amount of nitrogen assimilated by various crops over 

 a given area, wlien grown for many years in succession on the same 

 land without any nitrogenous manure ; that is, under conditions in 

 which the source of the nitrogen is as little as possible obscured by 

 the influence of indefinite amounts available from manure. 



It has been shown that tlie determined amounts of combined nitrogen 

 annually coming down in the measured aqueous deposits from the 



^.i 



