the Broad Beau and certain other Plants. 
659 
barley was clearly more susceptible to boric acid injury than the broad 
bean, for the toxic effect was so severe where 4 grm. H 3 B 0 3 per pot was 
applied, that plants survived in two cases only. The injury was first evident 
in a strongly marked retardation in germination ; the young shoots were 
yellow or even pink when they first appeared, but though they turned 
slightly green after about ten days, the majority of them failed to recover. 
The few survivors were extremely poor and scarcely tillered, and their leaves 
were badly spotted in a manner similar to that described for barley in water- 
culture experiments. Agulhon (1 (a)) has stated that this peculiar reddish 
tinge is a typical symptom of boron-poisoning in cereals. 
The crystalline substance deposited on the evaporation of the droplets 
of liquid which were exuded from the hydathode at the tip of the leaf-blade 
was collected from these chlorotic seedlings for several days in succession, 
the crystals from the control plants being collected separately at the same 
time. These two crystalline deposits were tested for boron by the following 
method, both a minute quantity of H 3 B 0 3 and distilled water being similarly 
tested as checks. 
The crystals were dissolved in a drop of 95 per cent, alcohol; two or 
three drops of acetic acid and alcoholic turmeric were added, and with the 
further addition of a few c.c. of distilled water the whole was evaporated to 
dryness on a water-bath. The residue in the case of the crystals from the 
chlorotic seedlings was reddish-brown in colour, and turned blue-black on the 
addition of a drop of NaOH, indicating the presence of boron. However, 
the residue from the crystals from the control plants remained yellow- 
brown in colour. 
It would seem, therefore, that the boron added to the soil was taken up 
by the roots and passed up through the plant by the transpiration stream, 
as has been described by Free ( 19 ) in the case of Pelargonuini ; consequently 
the injury evident in these plants is most probably due to the presence of 
boric acid in the plant tissues. 
Morse ( 26 ) has described a similar exudation of droplets from the 
leaf-margins of potatoes grown in pot culture in his experiments on borax 
in fertilizers. However, he makes no mention of testing such droplets for 
the presence of boron, though he detected it in the brown parts of the 
injured leaves. The grey deposit on the surface of the soil similar to that 
seen in the broad bean pot cultures was also noticed here. 
An application of 2 grm. H 3 B 0 3 per pot was not nearly so injurious as 
4 grm. (Table VIII), though germination was distinctly retarded and three 
of the fifteen plants died. Many of the young shoots were yellow or pink 
in colour, but they all turned green later and showed the typical brown 
flecking of the leaves. As fresh growth was made it rapidly became affected 
in the same way. All the plants tillered and came into ear: but the most 
striking feature of this set was their lateness in ripening, for when the 
