484 MB. J. B. LAVES, DB. GILBEBT, AM) DB PUOB OB 



adopted to avoid them. From known considerations with regard to the requirement* in 

 the soil and inorganic nutriment <>n the one hand, and in the atmosphere of the plants 

 on the other, and in all combined, we hare cam Lnded what are the proper condition! of 

 vegetable growth. It remains, however, to appeal to the results of direct experiment, to 

 show that our adopted conditions posBess the value which we have assumed them to ha 



A pot of good garden soil, capable of supporting luxuriant vegt tation in the open air, 

 was sown with Wheat, Barley, and Beans, and then placed under one of the experimental 

 shades, and submitted to exactly the same atmospheric conditions as those provided in 

 the experiments on the assimilation of Nitrogen. The result was, exceedingly luxuriant 

 growth (sec Records of growth in Appendix, Experiment No. L2, of " Plants grown in 

 1857," fig. 13, Plate XV.; and also Experiment No. 15, of "Plants grown in 1 - 

 It was thus proved that the aerial conditions supplied in our experiments were adapted 

 for healthy growth. 



"When pots of soil, prepared precisely as has been described above, were sown with seed 

 and combined Nitrogen artificially supplied, vigorous growth was the result. Hence it 

 was shown that the conditions of soil were properly selected. 



Section II— OTHER CONDITIONS OF EXPERIMENT, REQUIRING COLLATERAL 



INVESTIGATION. 



There remain to be considered several conditions which might affect the result of a 

 quantitative experiment on the assimilation of Nitrogen by plants, dependent upon the 

 reciprocal action of the air and the soil, with or without the connexion of the plant. 



The following conditions possibly affecting the result of such an experiment, due to the 

 mutual action of the soil, air, and organic matter of the plant, require to be considered : — 



1. The influence of ozone, cither within the cells of the plant, or in connexion with 

 it, in promoting the formation of nitrogenous compounds from free Nitrogen. The 

 influence of ozone in promoting such formation within the soil, either directly, or in con- 

 nexion with the organic matter of the plant. 



2. The decomposition of nitrogenous organic matter, in relation to the question 

 whether there be an evolution of free Nitrogen in the process. 



3. The formation of nitrogenous compounds, through the mutual action of nascent 

 hydrogen evolved by decomposing organic matter, and free Nitrogen. 



A. — General considerations in regard to the j)0ssible influence of Ozone on the 

 supply of combined Nitrogen to growing plants. 



The consideration of Ozone in connexion with the plant suggests the possibility of its 

 presence in two distinct ways. It may occur within the cells and intercellular passages 

 of the plant, either in the gaseous state or in solution, or it may be simply around the 

 plant, without existing within its structures. 



"With regard to the origin of Ozone in connexion with the plant, it may be a product 



