538 
ME. J. B. LAWES, DE. GILBEET, AKD DE. PUGH ON 
tional supply of combined Nitrogen would cause increased development, so long must 
the physiological conditions have been such as to require available Nitrogen, and they 
must therefore have been more or less favourable to the assimilation of free Nitrogen, 
proAided such assimilation were possible. Hence, the fact that this did not take place 
under the circumstances Avhich ha^n been described, seems to shoAV that, at least in the 
case of these Graminaceae, it is not possible. 
Some of the remarks Avhich Ave have made Avith regard to the influence of a supply of 
combined Nitrogen upon the growth of the Graminaceae, apply also, in a greater or 
less degree, to the other plants experimented upon. We shall not comment here in 
detail upon the value of each experiment, but simply call attention to the columns of 
gain or loss of Nitrogen, in the Tables, and to the notes in the Appendix indicating the 
circumstances of groAvth of the plants. 
With regard to the Leguminosae experimented upon, it is to be observed that the 
development Avas by no means so satisfactory as in the case of the Graminaceae. Hence 
the evidence Avhich the results relating to them afford against the fact of assimilation 
of free Nitrogen must be admitted to apply to a more limited range of conditions of 
groAvth, and, therefore, to be less conclusive against the possibility of such assimila- 
tion. Still, so far as they go, the results Avith these plants, and also those with buck- 
wheat, tend to confirm those obtained under the more favourable circumstances of 
growth with the cereals. It Avill be remembered, hoAvever, that M. Boussingault expe- 
rimented with a great many Leguminous plants, and generally succeeded in getting 
much more healthy groAvth than Ave were able to do in the cases to which the figures in 
the Tables refer. Yet in no case did he find any such gain of Nitrogen as to lead him 
to the conclusion that these plants, any more than the Graminaceae, assimilated free or 
uncombined Nitrogen. Our OAvn experiments with Leguminous plants are, however, 
not yet concluded ; so that Ave hope to supply some additional evidence on this subject, 
on a future occasion. 
Helcdions of the Plants grown with a su])])ly of ammonia to those grown without it. 
e have already called attention to the fact that the physiological phenomena exhi- 
bited in the progress of the plants grown under the tAVo different conditions as regards 
the supply of combined Nitrogen at their disposal, aflbrd satisfactory eAudence that the 
conditions provided in soil and atmosphere Avere all that were requisite in experiments 
for the solution of the question at issue with regard to the Cereals. The great develop- 
ment of these plants Avhen ammonia Avas supplied (Avhich was in fact almost in pro- 
portion to the amount supplied), the cessation of growth Avith the limit of the supply, 
together with the contrast between the growth with the aid of the ammonia and that 
Avithout it, all aflbrd evidence in one dhection in regard to the question at issue, so far 
as these plants are concerned. 
In Table XIV., relating to the plants to Avhich ammonia was supplied, an experiment 
Avith clover is recorded. Beference to the remarks in the Appendix, p. 573, Avill show 
