the Broad Bean and certain other Plants . 65 r 
After the plants had been set up in their respective solutions for about 
a fortnight, the shoots of all the plants receiving boric acid began to 
elongate rapidly, as is characteristic of the runner bean. No sign of this was 
seen in any of the five controls. Eventually the boron-treated plants 
attained a height of several feet and flowered profusely, but the controls 
remained stunted until the close of the experiment and never even formed 
flower buds (PI. XIII, Fig. 10). 
Some indication of a toxic influence was evident in the plants grown 
with 1 :100,000 H3BO3 in spite of the marked beneficial effect, for the lower 
leaves were inclined to turn yellow and some brown patches were seen. 
Apart from this slightly unfavourable appearance of the plants treated with 
the larger quantity of H 3 B 0 3 , there was little if any difference shown 
between the plants grown in the two concentrations of boric acid 
respectively. 
(b) Phaseolus mdgaris (Dwarf Bean—Sutton’s Canadian Wonder). 
The effect of boric acid on the dwarf bean was not seen so quickly as 
was the case with the runner bean. For some time all the plants were 
rather poor, probably owing to seasonal conditions, and it was impossible to 
note any appreciable difference between the sets, owing to the great lack of 
uniformity. However, after about three weeks’ growth, the boron-treated 
plants ran ahead of the controls, both shoot and root being better developed, 
though no striking contrast between the type of root was apparent. 
The control plants made very little growth indeed, and eventually all 
died, yet at first they were even a better green colour than the treated 
plants; the latter were decidedly yellowish, but grew to fair-sized plants,, 
flowered, and in some cases fruited. 
(c) Trifolium incarnatum (Crimson Clover). 
This plant gave particularly striking results which were confirmed by 
further experiments. Even after two days’ growth in their respective 
solutions a difference was noticeable in the root development, those without 
boric acid showing a curious bending at the tip with a tendency to a con¬ 
striction behind the bend, while the treated plants did not show this, or at 
most in a very small degree. Eater the lateral roots were distinctly better 
developed in both sets of plants grown with boric acid than in the controls. 
Ten days from the start of the experiment the untreated plants had 
developed a short and stunted root system, while those supplied with boric 
acid had long, fine roots, the difference becoming more accentuated as 
growth went on. The time when this abnormal type of root became 
apparent was evidently dependent upon seasonal conditions, for in the case 
of some Trifolium incarnaUnn plants, set up in ordinary nutrient solution in 
September, the roots for a considerable time closely resembled those which 
