The Sources of the Nitrogen of our Leguminous Crops. 675 
I 
than in either of tlie other pots. There were three small clusters 
of nodules on the roots of each of the three plants, one or two 
small bunches, and here and there a single nodule. But the 
clusters were much smaller, the total number of nodules was 
much less, and they were more generally distributed over the 
( roots in this pot with rich garden soil than in either of the 
j others, even than in pot 1 without soil-extract seeding. The 
root development was, however, as the description shows, much 
greater than in either of the other pots. There was, then, a 
greater development of root and root-fibre, but a less develop- 
ment of root nodules, in the garden soil, which itself supplied an 
abundance of combined nitrogen, as well as other nutriment. 
Upon the whole, the evidence relating to the peas clearly 
shows that there was a greatly enhanced development of nodules 
on the roots under the influence of the soil-extract seeding, 
and, coincidently with this, considerably increased growth. 
The nitrogen was determined in the sand and in the garden 
soil, at the commencement and at the conclusion of the experi- 
ments ; also in the seed, in the above-ground growth (stems and 
leaves), and in the roots, separately. The dry matter and ash 
were also determined, in the seed, and in the produce grown. 
It is of interest to remark (though the results are not here 
given) that the above-ground produce of the plants in pot 1, 
with the most restricted growth, and which from their pale 
colour indicated nitrogen-exhaustion, showed a lower percentage 
of nitrogen in its dry substance than was found in that of either 
of the other pots. It may be added that the roots in pots 2 and 
3, with the soil-extract, and with so much greater development of 
nodules than on those in either pots 1 or 4, also contained a 
considerably higher percentage of nitrogen in their dry substance. 
The next Table (IV.) shows the actual quantities of dry 
substance and of nitrogen in the separated and in the total 
products of growth. 
Table IV.— Peas, 1888. 
Dry substance 
Nitrogen 
In stems 
ami 
leaves 
In roots 
III 
whole 
plant 
In stem; 
and 
leaves 
In roots 
In 
w-hole 
plant 
gram's. 
grams. 
grams. 
erani. 
gi-am. 
gram. 
Pot 1. Sand without soil-extract . . . 
7 423 
2-000 
10-023 
u-2153 
0-0G(!9 
0-2822 
Pot 2. „ with soil-extract .... 
9-368 
2-409 
11-777 
0-4591 
0-0770 
0-53G1 
Pot 3. „ „ „ .... 
9-411 
1-748 
11-169 
0-3770 
0-05H7 
0-4357 
12-808 
2-846 
15-654 
0-5806 
0-0794 
0-6600 
Y Y 2 
