QUESTION OE THE SOURCES OF THE NITROOEH OF VEGETATION. 
85 
In the same year, 1858, another experiment was made with lupins, but in free air, 
one with hemp in free air, two with haricots, one in confined and one in free air, and 
one with 120 grams of the rich soil placed in a shallow vessel, kept moist with 
distilled water, and exposed to the free air as an experiment on fallow. In this last 
experiment, whilst there was a loss of about one-third of the carbon, the nitrogen 
increased from 0'31320 gram to 0'32184 gram, showing a gain therefore of 
0'00864 gram. 
Boussingault remarks that whilst the soil has lost a considerable quantity of its 
carbon by slow combustion, the nitrogen instead of diminishing has even increased, 
and that it remains to decide whether there has been nitrification, production, or simple 
absorption of ammonia. 
In introducing the report of the second series of experiments, those made in 1859, 
Boussingault says that he could not accept the gain of nitrogen by vegetable mould 
as sufficiently established, without repeating the exjieriments. It further remained to 
examine whether, in case there really were a fixation of nitrogen, it was as nitric acid, 
as ammonia, or as organic compounds. 
In reference to the result of the experiment made in 1859, as given in the table, 
Boussingault says that during the growdh of a lupin in a confined atmosphere, in 
130 grams of very rich soil, mixed with sand to favour the access of air, the plant, 
during 97 days, assimilated 0’0217 gram nitrogen from the soil, and yet the soil gained 
0’0454 gram nitrogen, only one-ninth of which pre-existed as nitric acid or ammonia. 
The total gain of nitrogen in plant and soil was 0'067l gram, a result which is almost 
identical with that found in 1858. He adds, that there is this curious coincidence, 
that in both cases it is by the soil, and not by the plant, that the gain has been effected. 
In the case of none of the other vegetation experiments in 1859 are the gains or 
losses by the soils given, so that the total gain or loss cannot be estimated. Bous¬ 
singault points out, however, that in 1859, there was about twice as much nitrogen 
taken up by a haricot growing in 100 grams of the soil, as by one growing in only 
50 grams in 1858. It may be added that haricots took up much more nitrogen in 
proportion to a given amount of soil than lupins. 
Referring to the main results, Boussingault says the singular fact appears, that 
the soil not only gained ammonia and nitrates, but organic matter also, possibly the 
remains of living organisms. On careful examination, he has observed that vegetable 
earth contains, not only dead organised matter, but living oi'ganisms, germs, the 
vitality of which is suspended by drying, and re-established under favourable con¬ 
ditions as to moisture and temperature. This mycodermic vegetation is not ahvays 
visible to the naked eye, and its progress must be followed by the aid of the micro¬ 
scope. The mycoderms have only an ephemeral existence, and they leave their 
detritus in the soil, which in time may give rise to ammonia and nitric acid. Even if 
the nitrogen of the air takes part in nitrification, a part of the nitrogen will exist in 
mycoderms, or their remains. 
