BULLETIN OF THE BUSSEY INSTITUTION. 253 
nitrogen to plants is not very clearly understood, or not allowed for to 
the extent that it deserves, or sometimes not even recognized. 
The experiments to be described directly were neither devised nor 
carried out with the idea of elucidating the present question, but for a 
totally different purpose; and it must be said of them, in so far as they 
may seem to conflict with the analogous experiments of Boussingault, 
that, as regards matters of analytic detail, they cannot be put in com- 
parison with the research of that observer. Though carefully and 
faithfully performed, they make no pretence to that elaboration and 
scrupulous attention to details which would naturally be demanded of 
any experimenter who might seek to review Boussingault’s work. To 
my mind no such review is needed. LBoussingault has given conclusive 
proof that plants are not nourished to any great extent by soil-nitrogen 
when supplied in the quantities and exposed to the conditions which 
obtained in most of his experiments. But it is none the less true of 
my own experiments, that they have clearly exhibited the power of 
plants to obtain support from the nitrogen of the soil, under the con- 
ditions in which they were performed. The sharp contrasts to be seen 
in the results of these experiments, accordingly as the nitrogen of 
peat or loam was or was not present in the pots, is a kind of evidence 
that cannot be readily discredited or lightly set aside. ‘The simplicity 
of the method, moreover, makes it easy for any one to perform an ex- 
periment for himself which will afford ocular demonstration of the 
most convincing character. I cannot but feel that the conclusions to 
which these experiments point have a direct and immediate bearing 
upon one of the most important problems in practical agriculture. 
The following record of results has been taken almost at random 
from a collection which contains many others of similar import. They 
are comparable for the most part with those on pages 54 to 70 of this 
Bulletin. It is to be remarked that in all the experiments I have 
sought to keep the temperature of the glass-house at from 68° to 70° F. 
by day, and at 48° to 50° by night. In point of fact the temperature 
of the house seldom rises above 82° or 83°, and very rarely falls below 
44° or 45°, during the season allotted to the experiments. The jars 
are constantly kept decidedly moist, but not overwet. ‘The comparative 
ease with which the soil contained in glass jars can be kept really moist, 
constitutes one of the chief advantages of these vessels for experimental 
purposes as compared with the ordinary porous earthen flower-pots. 
