555 



for want of a supply of available nitrogen in some form. During this 

 long period they were surrounded by an atmosphere containing free 

 nitrogen ; and their cells were penetrated by fluid saturated with that 

 element. It may be further mentioned, that many of the plants 

 formed glumes and paleae for seed. . 



It is to be observed that the results of these experiments with 

 cereals go to confirm those of M. Boussingault. 



The leguminous plants experimented upon did not grow so 

 healthily under the artificial conditions as did the cereals. Still, in all 

 three of the cases of these plants in which no combined nitrogen 

 was provided beyond that contained in the original seed, the carbon 

 in the vegetable matter produced was much greater than that in the 

 seed in one instance mo're than 3 times greater. In no case, how- 

 ever, was there any indication of assimilation of free nitrogen, any 

 more than there had been by the graminaceous .plants grown under 

 similar circumstances. 



One experiment was made with buckwheat, supplied with no other 

 combined nitrogen than that contained in the seed. The result gave 

 no indication of assimilation of free nitrogen. 



In regard to the whole of the experiments in which the plants 

 were supplied with no combined nitrogen beyond that contained in 

 the seed, it may be observed that, from the constancy of the amount 

 of combined nitrogen present in relation to that supplied, throughout 

 the experiments, it may be inferred, as well that there was no evolu- 

 tion of free nitrogen .by the growing plant, as that there was no 

 assimilation of it ; but it cannot hence be concluded that there would 

 be no such evolution if an excess of combined nitrogen were supplied . 



The results of a number of experiments, in which the plants were 

 supplied with more or less of combined nitrogen, in the form of am- 

 monia-salts or of nitrates, are recorded. Ten were with cereals ; 

 4 in 1857, and 6 in 1858. Three were with leguminous plants; 

 and there were also some with plants of other descriptions all in 

 1858. 



In the case of the cereals more particularly, the growth was very 

 greatly increased by the extraneous supply of combined nitrogen ; in 

 fact, the amount of vegetable matter produced was 8, 1 2, and even 

 30 times greater than in parallel cases without such supply. The 

 amount of nitrogen appropriated was also, in all cases many times 



