M. G. Ville on the influence of Nitrates on Vegetation. 501 



nitrate, even in cases in which nitrogenized oi-gauic matter, such 

 as bean -meal or gelatine, was added to the sand. The excess of 

 nitrogen could not therefore have arisen from a nitrification ; 

 nor could it have proceeded from an absorption of ammonia, for 

 if it had been so, why was it not also absorbed when the smaller 

 quantity of nitre was employed ? Ville considers that nitrogen 

 is absorbed by plants in three forms : as free nitrogen, as am- 

 monia, and as nitrate; and is of opinion that the assimilation of 

 an element may take place by the most contrary reactions. 



In the third ])art of his research, Ville seeks to establish that 

 the nature of the products formed during the decomposition of 

 manures, shows that plants absorb the gaseous nitrogen of the 

 atmosphere. The method of his experiments was as follows : — 

 To a pot filled with calcined sand, a certain quantity of bean- 

 meal was added. This pot was placed in a stoneware basin con- 

 taining water, and the whole covered with a bell-jar. Every 

 day 500 litres of air, carefully freed from any other nitrogenous 

 compound than nitrogen, was passed through. The air passing 

 from the bell-jar bubbled through a bulb containing weak 

 hydrochloric acid. By the action of the external temperature 

 water evaporated, and condensed on the interior surface of the 

 bell-jar. At intervals this was collected and evaporated to dry- 

 ness with oxalic acid; the hydrochloric acid in the bulb was 

 also treated in the same way. In these was contained the 

 nitrogen which had passed off as ammonia. Ville found, that of 

 0"238 grm. nitrogen added to the sand in the form of nitrogenous 

 matter, 0"093 grm. remained behind, 0"058 grm. passed off as 

 ammonia, and 0*087 grm. was lost in an indeterminate mannei'. 

 As no nitrate had been formed, he concluded that it had passed 

 off as free nitrogen. 



In another series of experiments, wheat was sown in calcined 

 sand to which bean-meal had been added. At the expiration of 

 the experiment, the quantity of nitrogen contained in the pro- 

 duce was estimated. As it was found to be greater than the 

 quantity furnished by the seed and by the ammonia formed in 

 the decomposition of the bean-meal, it was concluded that it was 

 derived from the direct absorption of gaseous nitrogen. 



His general conclusions are, that every organic substance in 

 decomposing loses a portion of its nitrogen as gaseous nitrogen ; 

 that the progress of this decomposition is not altered by vegeta- 

 tion ; that plants grown in a manured soil absorb more nitrogen 

 than would be furnished by the anmionia formed by the maiuire ; 

 and that the excess of this has been absorbed in the gaseous 

 state. 



His previous researches had led him to affirm that plants 

 absorb a certain quantity of nitrogen which is not accounted for 



