654 Warington .— The Effect of Boric Acid and Borax on 
dressing, 1 since this mode of application more closely resembled field 
methods. 
(a) Boric acid mixed throughout the soil (%l\ lb.). 4 grm. of H 3 B 0 3 
were strongly toxic ; besides being so injurious to the plant, a grey deposit 
wa’s noticed on the surface of the soil, giving it a most unhealthy appearance. 
This was thought to be due to a surface concentration of a boron compound, 
since it gave a very strong boron reaction on testing with the turmeric 
method. 
Germination was severely retarded in these pots and the plumules on 
emerging were frequently yellow, this chlorotic condition remaining for a con¬ 
siderable time in some cases. The retarding influence of boron compounds 
on the germination of seeds was noticed by Heckle ( 21 ) as early as 1875. 
Since that date, similar results with a large variety of plants have been 
obtained by a number of workers on the subject, including Archangeli ( 3 ), 
Morel ( 25 ), Agulhon (1 (a)), Voelcker ( 36 ), Sherwin ( 34 ), Blair and Brown ( 7 ), 
and Neller and Morse ( 27 ). 
As growth went on, the plants became light green, but the leaves 
turned brown along their margins in a manner similar to that described in 
the water-culture experiments. Spotting of the leaves, as was seen in 
barley, never occurred. The injury was at first apparent in the lower 
leaves, but nearly all of them showed it later. Growth was very slow, but 
eventually several of the plants flowered. 
2 grm. H3BO3 per pot were decidedly less toxic than 4 grm. (Table VI), 
germination being less retarded and the plants flowering better; however, 
the leaves were inclined to be yellowish and showed signs of quite severe 
poisoning ; where only 1 grm. H 3 B 0 3 was applied, toxic effects were rare, 
brown leaf-margins being seen in isolated cases only, and the green and dry 
weights being only slightly depressed (Table VI). Plants receiving lower 
dressings were quite similar in colour and general appearance to the controls, 
though some superiority in height was evident where 0-5 or o-i grm. had been 
applied. This apparent stimulation was also noticeable in the green weight, 
an increase of 14*4 per cent, being obtained with the larger quantity; the 
rise in dry weight, however, was practically negligible (Table VI and Text- 
fig. 5). Neller and Morse ( 27 ) have noticed a similar indication of stimula¬ 
tion to the eye in the case of Phaseolus in pot culture, but here also no 
increase in the dry weight was realized, even the beneficial appearance 
having disappeared at the close of the experiment. 
The untreated plants were in every way perfectly normal: the 
phenomenon of ‘ dying off’, of universal occurrence in broad bean plants 
grown in water culture without boron, did not occur in a single instance; 
in fact the pot-culture control plants closely resembled the sets in water 
culture which were supplied with low concentrations of boric acid. 
, 1 The II 3 T 50 3 was sprinkled evenly over the surface of the soil and the pots watered. 
