632 Warington .— The Effect of Boric Acid and Borax on 
The nutrient solutions were renewed frequently. Three weeks usually 
elapsed before the first change, but later fresh solution was supplied at fort¬ 
nightly or weekly intervals. The bottles were kept well filled with distilled 
water between the renewing of the solutions. Sufficient aeration of the 
roots seemed to be effected by this means. The plants were grown in 
separate bottles, each of 600 c.c. capacity. 
A. Broad Beans. 
The variety of broad bean used throughout this work was Sutton’s 
Prolific Longpod, and the seed was graded by weight for each experiment. 
a. The Effect of Different Concentrations of Boric Acid in the Nutrient 
Solution. 
In the first three series the effect of a wide range of concentrations of 
H3BO3 was tried, viz. from 1 : 5,000 to 1 :100,000,000. 
Five or ten plants were taken as the unit. 
The experiments were carried out at three different seasons of the year, 
spring, early summer,and autumn respectively. Consequently, the plants were 
grown under totally different conditions of light, temperature, and humidity. 
However, in spite of this, and the corresponding variation in such vital plant 
processes as transpiration, carbon assimilation, and respiration, the main 
results in all three cases were consistent, showing that seasonal changes 
cannot in anyway be responsible for the remarkable effects attributed to the 
action of boric acid. 
(a) Development of the root. Differences between the plants were first 
evident in the root system, being noticeable after only five to seven days’ 
growth in their respective solutions. 
H z BO 3 1:jooo. 
The root development was poor, but on the whole better than that of 
the controls, though in a comparison of their dry weights little difference 
was seen (Table I). The first-formed laterals also showed a strong ten¬ 
dency to arise in the upper portion of the primary root, above the solution, 
and to grow out at a wide angle as if trying to avoid entering the liquid 
(Text-fig. 1). Later the rootlets were more evenly distributed and altogether 
appeared quite normal. A few isolated cases of curled root-tips were 
noticed, but it was uncertain whether this was due to the poisonous nature 
of the solution or to some mechanical factor. 
IT z BO z 1: 2 j,ooo and 1 : j 0,000. 
These two sets showed up very strikingly after a week’s growth. The 
laterals were more numerous than in any other set, and there was only 
a slight tendency shown for them to be at first localized in the upper portion 
