Influence of Aeration of Nutrient Solution. 193 
in the aerial environment it is not possible to sap. The atmospheric 
conditions seemed much the same in the three series of experiments, 
nor was there much difference in the total period of illumination. 
Nevertheless in the absence of exact measurement it is impossible 
to draw any conclusions in the matter. It will also be observed 
that the total leaf development is considerably greater in the third 
series as compared with the first and second. This improvement is 
also shown in the dry weight results. We give the results of 
individual plants in order to show the sort of differences obtained 
between different individuals when steps are taken to reduce 
inherited differences to a minimum. 
Aerated. 
Plant 
Dry Weight in grams 
Shoot Root 
Whole Plant 
1 
1-553 
0-722 
2-275 
2 
1-328 
0-600 
1-928 
3 
1-393 
0-701 
2-094 
4 
1-250 
0-624 
1-874 
5 
1-503 
0-624 
2-127 
6 
1-584 
0-733 
2-317 
7 
1-434 
0-629 
2-063 
8 
1-532 
0-619 
2-151 
9 
1-480 
0-442 
1-920 
10 
1-482 
0-858 
2-340 
Mean ... ... 2-109 + 0-025 
Non-aevated. 
Plant 
Dry Weight in grams 
Shoot Root Whole Plant 
1 
1-306 
0-446 
1-752 
2 
1-135 
0-549 
1-684 
3 
0-918 
0-369 
1-287 
4 
1-006 
0-320 
1-326 
5 
1-106 
0-334 
1-440 
6 
1-316 
0-458 
1-774 
7 
1-471 
0-487 
1-958 
8 
1-601 
0-501 
2-102 
9 
0-909 
0-308 
1-217 
10 
1-837 
0-582 
2-419 
Mean ... ... 1 696 0083 
This shows an increase of dry weight of the aerated cultures 
over the non-aerated of 24 per cent., after 50 days from sowing. This 
is practically the same as the increase in leaf development. It will 
be observed that the probable error of experiment in the case of 
the dry weight of the aerated cultures is 1-2%, and in the case of 
the non-aerated 4-7%. The recorded difference in dry weight 
