the Broad Beau and certain other Plants. 
of the root (Text-fig', i). Of the two, the i : 25.000 set more nearly resembled 
the 1 :5,coo, while in the plants grown with 1 : 50,000 H 3 B 0 3 but few of the 
characteristics of the roots grown in the strongest solution were evident; 
thus it would seem that the high concentration of the boric acid was the factor 
responsible for any peculiarities in growth in the latter solution. 
HpO^ 1 : 100,000, 1:500 000, and 1: 2,500,000. 
The roots of the plants in these concentrations were slower in developing 
than those receiving a somewhat larger quantity. None of the character- 
1'5,000 Boric Acid 
l'50 r 000 Boric Acid 
No BoricAcid 
Text-fig. i. Typical broad bean seedlings after five days’ growth in a nutrient solution with or 
without boric acid. 
istics of the 1 : 5,coo set were seen, but, on the other hand, growth was not 
so good as in the case of plants treated with 1 :50,000 H 3 B 0 3 . 
H.J 30 . d 1:12500,000 and 1 : 100,000.000. 
As might be expected, the plants in the most dilute solution of boric 
acid showed little difference in their root development from the untreated 
plants, but those in 1 : 12,500,000 H 3 B 0 3 made decidedly more growth than 
either the 1 : 100,000.000 set or the controls, and the dry weight figures 
bear this out (Table I). 
Control: no Boric Acid supplied. 
At first the development of the root compared favourably with the other 
sets, but very soon fell behind (Text-fig. 1). In the majority of cases the 
