554 



with combined nitrogen in a more liberal measure. It has been 

 sought to provide these conditions in the experiments under con- 

 sideration. 



In the selection of plants, it was thought advisable to take such as 

 would be adapted to the artificial conditions of temperature, moisture, 

 &c. involved in the experiment, also such as were of importance in 

 an agricultural point of view to have representatives, moreover, of 

 the two great Natural Families, the Graminacese and the Leguminosae, 

 which seem to differ so widely in their relations to the combined 

 nitrogen supplied within the soil and finally, to have some of the 

 same descriptions as those experimented upon by M. Boussingault, 

 and M. G. Ville, with such discordant results. 



Thirteen experiments were made, 4 in 1857 and 9 in 1858, in 

 which the plants were supplied with no other combined nitrogen 

 than that contained in the original seed. In 1 2 of the cases pre- 

 pared soil was the matrix, and in the remaining one prepared 

 pumice. 



Of 9 experiments with graminaceous plants, 1 with wheat and 2 

 with barley were made in 1857. In one of the experiments with 

 barley there was again of 0*0016, and in the other of 0*0026 gramme 

 of nitrogen. In only two cases of the experiments with cereals in 

 1858, was there any gain of nitrogen indicated; and in both it 

 amounted to only a small fraction of a milligramme. Indeed, in no 

 one of the cases, in either 1857 or 1858, was there more nitrogen in 

 the plants themselves, than in the seed sown. A gain was indicated 

 only when the nitrogen in the soil and pot which together weighed 

 about 1500 grammes was brought into the calculation. Moreover, 

 the gain only exceeded 1 milligramme in the case of the experiments 

 of 1 85 7, when slate, instead of glazed earthenware stands were used 

 as the lute vessels ; and there was some reason to believe that the 

 gain indicated was due to this circumstance. In none of the other 

 cases was the gain more than would be expected from error in 



The result was then, that in no one case of these experiments was 

 there any such gain of nitrogen as could lead to the supposition that 

 free nitrogen had been assimilated. The plants had, however, vege- 

 tated for several months, had in most cases more than trebled the 

 carbon of the seed, and had obviously been limited in their growth 



