QUESTION OP THE SOURCES OP THE NITROGEN OP VEGETATION. 
159 
the influence of extract from any cultivated soil, but lupins and serradella only when 
extract from a soil where these plants were growing was used. The series comprised 
178 pots, and the results were so accordant, as was shown by photographs exhibited, 
that the possibility of accident, or nitrogenous impurities, was out of the question. 
Thus, it may be considered established that the Papilionacese can take the whole 
of their nitrogen from the air. 
The experiments of the preceding year had shown that the peas did not derive 
their nitrogen from the small quantity of combined nitrogen in the air, and new 
experiments fully confirmed this. Following the plan of Boussingault, they put 
4 kilog. of ignited sand in a large glass balloon, added mineral constituents and a 
small quantity of the soil-extract, and then sowed one seed of oats, one of buckwheat, 
and one of peas. The vessel was then perfectly closed by a well-ground glass stopper; 
but carbonic acid was occasionally supplied. The oats and buckwheat only grew so 
long as the supply of nitrogen of the seed lasted ; but the peas continued to grow 
luxuriantly and quite normally. A large part of the produce was found to contain 
6'55 grams dry substance, and 0T37 gram nitrogen. 
The author says that it cannot yet be with certainty explained in what way the 
soil-extract enables the Papilionacese to assimilate the nitrogen, and that it is even 
doubtful whether the root-nodules have any connection with the taking up of the 
nitrogen. It is, however, proved that the soil-extract favours the development of the 
nodules, whilst the sterilised extract has no such effect. It seems natural to attribute 
the action to bacteria, and to connect it with the organisms in the nodules, but the 
experiments do not as yet settle the question. 
The amount of nitrogen in the seed is not given, but to show how considerable the 
assimilation of nitrogen may be, the following results, showing the amounts of dry 
substance, and of nitrogen, in the produce of a number of the pots of lupins, are 
quoted :— 
Without soil-extract. 
With soil-extract. 
Dry matter. 
Nitrogen. 
Dry matter. 
N itrogen. 
Nos.< 
grams. 
grams. 
Nos. 
grams. 
grams. 
9 
0-918 
0-0146 
3 
4473 
1-099 
10 
0-800 
0-0136 
4 
45-62 
1-156 
11 
0-921 
0-0132 
5 
44-48 
1-194 
12 
1-021 
0-0133 
6 
42-45 
1-337 
Such is the brief account of the experiments as yet published by Dr, Wilfarth ; 
and that full confidence was placed in the results by those present may be inferred, 
since the report states that the communication was received with great applause ; 
whilst in the discussion which followed, Drs. Nobbe, Heiden, Liebschee, Fleischer, 
and Emil von Wolff, took part. 
