650 Waring ton .— The Effect of Boric Acid and Borax on 
y. Comparison between the Effect of Boric Acid on Broad Beans and 
Barley. 
From the results of the water-culture experiments on these two plants, 
it is evident that barley is less able to stand high concentrations of H 3 B 0 3 
than the broad bean, for the latter made excellent growth in a solution 
which was highly poisonous to barley, viz. 1 :50,000 H 3 B 0 3 , and further 
1 : 12,500,000 H 3 B 0 3 , which was just below the toxic limit for barley, was 
barely enough to ensure healthy growth of the broad bean. 
Barley, on the one hand, can apparently make approximately optimum 
growth in the absence of any boron compound, and would therefore seem 
more or less indifferent to its presence, provided that the quantity is not 
sufficient to be toxic; on the other hand, the ordinary nutrient solution has 
been shown to be inadequate for even normal development of the broad 
bean, but the addition of a small amount of boron is able to supply some 
factor which is lacking. 
Since boron had been detected in the broad bean seed, that of the 
barley was tested in a similar manner, but in this case practically no boron 
was found. Some explanation is therefore afforded for the different reaction 
of the two plants towards the presence of boric acid in the nutrient solution, 
for the occurrence of an element in the reserve food of the seed might 
possibly indicate the importance of that element to the plant in question. 
C. Mis cell aneous Plants. 
Since the addition of small quantities of boric acid to the nutrient 
solution caused such striking results in the growth of the broad bean plant, 
a number of other plants were tested in a similar manner. Although 
Agulhon (1 ( a)), in particular, has shown that the importance of boron is by 
no means confined to the Leguminosae, it is evident from several workers, 
Cook ( 16 ) and Morse ( 26 ) for example, that certain members of this Natural 
Order readily respond to its influence. Accordingly the majority of the 
plants chosen were of this group. 
In each case fifteen plants were set up in ordinary culture solution at 
the beginning of August 1922; five receiving in addition 1 12,500,000 
F 3 B 0 3 and five 1 : 300,000 H 3 B 0 3 . All the seeds were graded, with the 
exception of the clovers. 
(a) Phaseolus multijlorns (Runner Bean—Sutton’s Prizewinner). 
From the start the plants supplied with boric acid made better growth 
than the controls, the difference being first noticeable in the better develop¬ 
ment of lateral roots. Later a distinct difference in the type of root was 
evident, those in the control solution being short and thick, while the boron- 
treated plants had long fine roots. 
