The Sources of the Nitrogen of our Legnminov.t Crops. 669 
That, under the conditions described, the Lerjuminosce, as 
well as the Gramineiv, can take up and assimilate already com- 
bined nitrogen supplied to them is well illustrated in the experi- 
ments made in 1860 with Lecjnminosce alone. The series com- 
j prised three experiments with white haricot beans : No. 1 with- 
I out any other supply of combined nitrogen than that in the seed ; 
I No. 2 with a fixed quantity of nitrogen applied as ammonium 
sulphate, and No. 3 with a fixed quantity supplied as nitrate ; 
also three experiments with white lupins : No. 1 , as with the 
haricots, without artificial supply of combined nitrogen ; No. 2 
with supply as ammonium sulphate, and No. 3 as nitrate. Each 
of these two descriptions of leguminous plant showed consider- 
ably increased growth under the influence both of ammonium 
sulphate and of nitrate — indeed, the growth was much more 
satisfactoi-y than in the earlier experiments. Still, owing to the 
atmospheric conditions within the shades, as above referred to, 
the plants lost both leaves and flowers, and were therefore taken 
up earlier than they otherwise would have been. The analytical 
results here again indicated no gain from free nitrogen, either in 
the experiments without, or in those with, an artificial supply of 
combined nitrogen — indeed, the losses were gi-eater than the 
gains. 
Such, then, ivere the negative results ohtained when plants were 
groivn under conditions of sterilisation and of enclosure. There 
was, under such conditions, no gain from free nitrogen, in tlie 
growth of either Graminece, Leguminosce, or other plants. 
Receot Experiments, which do show Fixation of Free 
Nitrogen. 
It was about the year 187G that M. Berthelot called in 
question the legitimacy of the conclusion that plants do not 
assimilate the free nitrogen of the air, when drawn from the 
results of experiments in which the plants are so enclosed as to 
exclude the possibility of electrical action ; and more recently 
he has objected to experiments so conducted with sterilised 
materials, on the ground that, under such conditions, the pre- 
sence, development, and action of micro-organisms are excluded. 
So far there is, however, nothing in the recent results, either of 
M. Berthelot himself or of others, which can beheld to invalidate 
the conclusion which had been drawn from the results of Bous- 
singault, and from those obtained at Rothamsted, that the 
higher chlorophyllous plants do not directly assimilate free 
nitrogen. 
