662 ‘ Waring ton.—The Effect of Boric Acid and Borax on 
suggestive of plants supplied with excessive nitrate, and the analogy was 
carried further in their lateness in maturing. 
o*5 grm. H3BO3 was also decidedly injurious, and the equivalent 
dressing of borax again proved more toxic, being in this case accompanied by 
a slight decrease in dry weight (Table IX). The injury was most apparent 
in quite the early stages of growth ; the retardation in ripening was only 
very slight. Where o-i grm. H 3 B 0 3 or the equivalent quantity of borax 
was applied, toxic effects were rare, and at the close of the experiment 
these plants were slightly superior both to those receiving lower dressings 
and the controls ; however, no stimulation was apparent from either the 
green or dry weight figures as in the previous experiments (Table IX). 
This discrepancy may be due to the seasonal conditions under which the 
experiments were respectively carried out, or possibly the beneficial effect 
may only be realized in the weight of the plant at a certain stage in its 
growth ; in the one case, the plants may have been harvested before that 
stage had been reached, and further, such a stage may itself depend on 
seasonal conditions, being reached sooner in some years than in others. 
Table VIII. 
Mean Green and Dry Weights of Barley grown in Pot Culture. 
Average of 5 pots. 3 plants per pot 0 
Mixed throughout soil. Top-dressed 15 days after sowing. 
Feb. 2^-JulyS, 1921. April 15-Aug. 6, 1921. 
If 0 Oo per 
pot. 
Green IVt. 
Dry IVt. 
% Dry in 
Green. 
Green IVt. 
Dry IVt. 
% Dry in 
Green. 
grm. 
grm. 
grm. 
grm. 
grm. 
4-0 
2°- I 5 
5. 10 
2 5 - 3 o 
0.0 
0-0 
— 
2-0 
5^-44 
18-34 
36-37 
13.89 
5 - 1 8 
37-29 
1-0 
69.70 
29.99 
43-°3 
26-68 
9.99 
37-44 
°’5 
75 - 9 2 
33-86 
44.61 
41.56 
16-00 
38-50 
o-i 
81-26 
35 - 9 ° 
44 -i 8 
39'83 
26-16 
65-67 
0*02 
76-74 
34*39 
44-81 
32-35 
22-07 
68-21 
Control 
7473 
34 - 3 ° 
45 - 9 ° 
34-29 
21-82 
63-64 
Agulhon (1 (a)) has attributed the increase in the green weight value of 
plants grown with even slightly toxic doses of boric acid to an increase in 
water-holding capacity resulting from a state of over-mineralization, 
induced by the absorption of more than normal quantities of boron. 
Such an increase in water-content is shown up well by the values for the 
percentage of the dry in green weight in the various sets (Tables VIII and 
IX). In the case of the heavily treated plants which were so strikingly late 
in maturing, the value is very little more than half that of the controls, but the 
figure approximates to normal in those sets which show definite injury with 
a comparatively light dressing of boric acid. 
1 Pots containing fewer than three plants were included in the mean, as they only occurred in 
heavily treated sets and were not caused by normal failure of germination. 
