Ii;i \IK. .1. B. LAWBS, DB. GILBERT, AM) DB. PI 'fill OH 



that supplied iii the combined form, was ob ei vi d t<> be the largest in some of thi i 

 where qo nitrogenous manure was employed, and where the total amount of comb in ed 

 Nitrogen within the react of the plants was confined to a (en milligrammes only, con- 

 tained in the original young plants or seeds that were planted. In some such instanci . 

 the amounl of combined Nitrogen found in the products was aboul forty times a> much 

 as was supplied. In other cases, the assimilation of free nitrogen onlj seemed to take 



place when the activity, and Btage of growth, of the plants, had been forced beyond a 



certain point by the use of considerable amounts of nitrogenous manure. 



Results and conclusions so astonishingly conflicting a> those of M. Boi --im.ai'i.t and 

 M. (■. Yn.u:. have naturally incited others, either to investigate anew, or to seek, in 

 the conditions provided in their experiments, for some explanation of the discordance. 

 Before entering upon the consideration of our own experiments bearing upon the points 

 in question, it will be desirable to add to the foregoing review a brief notice- of the 

 labours, or opinions, of these other experimenters or arbitrators. 



C. — M. Mene's Experiments*. 



In 1851, M. Mexe made some experiments in reference to the assimilation of Nitrogen 

 by plants. He seems to assume that BoTJSSINGAULT had concluded from his experiments 

 that the free Nitrogen of the atmosphere was appropriated by plants; and he refers to 

 the experiments of M. G. Ville as confirmatory of such a view. M. Mene made three 

 sets of experiments in reference to this question. 



1. He grew "Wheat and Peas, respectively, in powdered glass as soil, allowing them 

 contact with common air, and watering them with pure water. The Wheat increased 

 in Nitrogen in amount equal to one-fourth of that contained in the seed sown ; whilst 

 its carbon, hydrogen, and oxygen were double those of the seed. The Pea-plants 

 doubled the carbon, oxygen, and hydrogen of the seed sown, and their Nitrogen was 

 threefold that of the seed. 



2. Lentils, Peas, Haricots, Beans, Wheat, Bye, and Oats were grown in a sterile 

 matrix under a bell-glass. They were respectively supplied with an atmosphere of 

 known composition, and with acetate of ammonia in the soil. The plants increased in 

 Nitrogen, and the ammonia in the soil diminished ; but the free Nitrogen of the air was 

 not perceptibly affected. 



3. This series of experiments was in every way similar to the second, with the excep- 

 tion that the Nitrogen of the air was replaced by hydrogen. The plants flourished, 

 and took up some of the acetate of ammonia. 



M. Mene concludes that plants do not appropriate the free Nitrogen of the air. 



D. — M. Boy's Views ox the subject of the Assimilation of Nitkogex by Plants ■}• . 



M. Boy gave a paper on this subject in 1854. His supposition was that carbonate of 

 ammonia constituted the chief source of Nitrogen to plants. Leguminous plants, he 

 * Compt. Eend. xssii. t Ibid, xxxix. 



