616 Ml,'. J. B, I.WVKs. DB. GILBERT, AND DR. PTJOH OH 



gen of the decomposing nitrogenous body. Or, if it did acl upon the latter in prefi 

 to the former, there would either be do free Nitrogen finally evolved, or, in i 

 trogen being lost in the free state, it would be obvious thai there bad been l< 

 Nitrogen converted into ammonia than had been liberated from it- combinations, and 

 hence that, as a resultant, there would be a loss and not a gam of combined Nitrogen 

 due to the decomposition. 



The fact that, in our experiments upon the gas evolved bj vegetable matters in a I 

 of decomposition, both free Nitrogen and free- hydrog ven off, bears strongly 



upon this question. The Nitrogen evolved has been in most intimate contact with the 

 hydrogen given off. It has, indeed, been in the identical cells by the decomposition of 

 the walls or contents of which the hydrogen was set free; yet both appear as g 



From the above considerations it would appear that we need be under little appre- 

 hension of error in the results of our experiments on the question of t .ilation 

 of free Nitrogen by plants, arising from an unaccounted supply of ammonia formed under 

 the influence of nascent hydrogen, given off in any decomposition of the organic matter 

 involved in the experiment. 



Summary Statement of the Results of the foregoing consideration of the conditions reguired, 

 or involved, in Experiments on the question of the assimilation of free Nitrogen In/ 

 Plants. 



Before entering upon the discussion of the results of our direct experiments upon the 

 question whether or not plants assimilate free Nitrogen, it will be well, for the sake of 

 perspicuity, to give a very brief enumeration of the results arrived at in the foregoing 

 Sections I. and II. (Part II.), relating to the conditions of experiment required, and to 

 the collateral investigations involved, in the inquiry. They may be stated as follow : — 



1. Conditions of soil or matrix which are both adapted for healthy growth and are 

 consistent with the other requirements of the investigation can be attained (Section I. 

 Sub-sections A, p. 470, and L, p. 484). 



2. The requirements of the experiment in regard to the selection of seeds or plants 

 for growth, to the nutriment to be supplied in the soil, to the water, to the atmosphere, 

 to the carbonic acid, and to other conditions involved, can be satisfactorily met (Sec- 

 tion I. Sub-sections B-J, inclusive, pp. 472-481; and L, p. 484). 



3. The conditions of experiment adopted have several advantages over some of those 

 which have been suggested, or adopted, by others (Section I. Sub-section K, pp. 481- 

 483). 



4. The mutual actions of the soil, air, organic matter in the soil or in the plant, are 

 not such as to be likely to affect the result of the experiment, by yielding to the plants 

 a quantity of combined Nitrogen not taken into account. The influence of Ozone as a 

 possible element in these actions would be less, in the circumstances of the experiments 



